Evidence Report/Technology Assessment
Number 210
Screening and
Diagnosing Gestational
Diabetes Mellitus
Evidence-Based
Practice
Evidence Report/Technology Assessment
Number 210
Screening and Diagnosing Gestational Diabetes
Mellitus
Prepared for:
Agency for Healthcare Research and Quality
U.S. Department of Health and Human Services
540 Gaither Road
Rockville, MD 20850
www.ahrq.gov
Contract No. 290-2007-10021-I
Prepared by:
University of Alberta Evidence-based Practice Center
Edmonton, Alberta, Canada
Investigators:
Research Team:
Lisa Hartling, Ph.D.
Donna M. Dryden, Ph.D.
Alyssa Guthrie, M.S.Sc.
Melanie Muise, M.A.
Ben Vandermeer, M.Sc.
Walie M. Aktary, B.Sc., B.Ed.
Dion Pasichnyk, B.Sc.
Jennifer C. Seida, M.P.H.
Clinical Investigator:
Lois Donovan, M.D., FRCPC
AHRQ Publication No. 12(13)-E021-EF
October 2012
This report is based on research conducted by the University of Alberta Evidence-based Practice
Center under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville,
MD (Contract No. 290-2007-10021-I). The findings and conclusions in this document are those
of the authors, who are responsible for its contents; the findings and conclusions do not
necessarily represent the views of AHRQ. No statement in this report should be construed as an
official position of AHRQ or of the U.S. Department of Health and Human Services.
The information in this report is intended to help health care decisionmakers—patients and
clinicians, health system leaders, and policymakers, among others—make well-informed
decisions and thereby improve the quality of health care services. This report is not intended to
be a substitute for the application of clinical judgment. Anyone who makes decisions concerning
the provision of clinical care should consider this report in the same way as any medical
reference and in conjunction with all other pertinent information, i.e., in the context of available
resources and circumstances presented by individual patients.
This report may be used, in whole or in part, as the basis for development of clinical practice
guidelines and other quality enhancement tools, or as a basis for reimbursement and coverage
policies. AHRQ or U.S. Department of Health and Human Services endorsement of such
derivative products may not be stated or implied.
This document is in the public domain and may be used and reprinted without permission except
those copyrighted materials that are clearly noted in the document. Further reproduction of those
copyrighted materials is prohibited without the specific permission of copyright holders.
Persons using assistive technology may not be able to fully access information in this report. For
assistance contact EffectiveHealthCare@ahrq.hhs.gov.
None of the investigators have any affiliations or financial involvement that conflicts with the
material presented in this report.
Suggested citation: Hartling L, Dryden DM, Guthrie A, Muise M, Vandermeer B, Aktary WM,
Pasichnyk D, Seida JC, Donovan L. Screening and Diagnosing Gestational Diabetes Mellitus.
Evidence Report/Technology Assessment No. 210. (Prepared by the University of Alberta
Evidence-based Practice Center under Contract No. 290-2007-10021-I.) AHRQ Publication No.
12(13)-E021-EF. Rockville, MD: Agency for Healthcare Research and Quality. October 2012.
www.effectivehealthcare.ahrq.gov/reports/final.cfm.
ii
Preface
The Agency for Healthcare Research and Quality (AHRQ), through its Evidence-based
Practice Centers (EPCs), sponsors the development of evidence reports and technology
assessments to assist public- and private-sector organizations in their efforts to improve the
quality of health care in the United States. The reports and assessments provide organizations
with comprehensive, science-based information on common, costly medical conditions, and new
health care technologies and strategies.
The EPCs systematically review the relevant scientific literature on topics assigned to them
by AHRQ and conduct additional analyses when appropriate prior to developing their reports
and assessments. To bring the broadest range of experts into the development of evidence reports
and health technology assessments, AHRQ encourages the EPCs to form partnerships and enter
into collaborations with other medical and research organizations. The EPCs work with these
partner organizations to ensure that the evidence reports and technology assessments they
produce will become building blocks for health care quality improvement projects throughout the
Nation. The reports undergo peer review and public comment prior to their release as a final
report.
AHRQ expects that the EPC evidence reports and technology assessments will inform
individual health plans, providers, and purchasers as well as the health care system as a whole by
providing important information to help improve health care quality.
We welcome comments on this evidence report. Comments may be sent by mail to the Task
Order Officer named in this report to: Agency for Healthcare Research and Quality, 540 Gaither
Road, Rockville, MD 20850, or by email to epc@ahrq.hhs.gov.
Carolyn M. Clancy, M.D.
Director
Agency for Healthcare Research and Quality
Jean Slutsky, P.A., M.S.P.H.
Director, Center for Outcomes and Evidence
Agency for Healthcare Research and Quality
Stephanie Chang, M.D., M.P.H.
Director
Evidence-based Practice Program
Center for Outcomes and Evidence
Agency for Healthcare Research and Quality
Suchitra Iyer, Ph.D.
Task Order Officer
Center for Outcomes and Evidence
Agency for Healthcare Research and Quality
iii
Acknowledgments
The authors gratefully acknowledge the following individuals for their contributions to this
project: Tamara Durec (searching), Andrea Milne (searching, technical support), Teodora
Radisic (article retrieval), Jocelyn Shulhan (screening), Annabritt Chisholm (research support,
reference management), and Noah Toppings (development of Figure 1). We thank Dr. Alun
Edwards for providing clinical input throughout the project.
Technical Expert Panel
Howard Berger, M.D.
Assistant Professor
Health Policy, Management, and Evaluation
University of Toronto
Toronto, ON
Wanda K. Nicholson, M.D., M.P.H., M.B.A.
Associate Professor
Obstetrics and Gynecology
University of North Carolina
Chapel Hill, NC
Siri L. Kjos, M.D., M.S.Ed.
Clinical Faculty
David Geffen School of Medicine
University of California, Los Angeles
Torrance, CA
Leann Olansky, M.D.
Medical Director
Lennon Diabetes Center, Huron Hospital
Cleveland Clinic East
Cleveland, OH
Joy Melnikow, M.D., M.P.H
Professor
Family and Community Medicine
University of California, Davis
Sacramento, CA
iv
Peer Reviewers
Hélène Long, M.D.
Endocrinologist
Cité de la Santé de Laval Hospital
Laval, QC, Canada
Florence Brown, M.D.
Assistant Professor, Harvard Medical
School
Director, Joslin-Beth Israel Deaconess
Diabetes and Pregnancy Program
Boston, MA
Julia Lowe, M.D.
Associate Professor, Endocrinology
University of Toronto, Sunnybrook Health
Sciences Center
Toronto, ON, Canada
William Callaghan, M.D., M.P.H.
Senior Scientist
Maternal and Infant Health Branch
Division of Reproductive Health
National Center for Chronic Disease
Prevention and Health Promotion
Atlanta, GA
James Peter VanDorsten, M.D.
Professor
Department of Obstetrics and Gynecology
Medical University of South Carolina
Charleston, SC
Robert P. Kauffman, M.D.
Professor
Department of Obstetrics and Gynecology
Texas Tech University
Lubbock, TX
v
Screening and Diagnosing Gestational Diabetes
Mellitus
Structured Abstract
Background. There is uncertainty as to the optimal approach for screening and diagnosis of
gestational diabetes mellitus (GDM). Based on systematic reviews published in 2003 and 2008,
the U.S. Preventive Services Task Force concluded that there was insufficient evidence upon
which to make a recommendation regarding routine screening of all pregnant women.
Objectives. (1) Identify properties of screening tests for GDM, (2) evaluate benefits and harms
of screening for GDM, (3) assess the effects of different screening and diagnostic thresholds on
outcomes for mothers and their offspring, and (4) determine the benefits and harms of treatment
for a diagnosis of GDM.
Data Sources. We searched 15 electronic databases from 1995 to May 2012, including
MEDLINE and Cochrane Central Register of Controlled Trials (which contains the Cochrane
Pregnancy and Childbirth Group registry); gray literature; Web sites of relevant organizations;
trial registries; and reference lists.
Methods. Two reviewers independently conducted study selection and quality assessment. One
reviewer extracted data, and a second reviewer verified the data. We included published
randomized and nonrandomized controlled trials and prospective and retrospective cohort studies
that compared any screening or diagnostic test with any other screening or diagnostic test; any
screening with no screening; women who met various thresholds for GDM with those who did
not meet various criteria, where women in both groups did not receive treatment; any treatment
for GDM with no treatment. We conducted a descriptive analysis for all studies and metaanalyses when appropriate. Key outcomes included preeclampsia, maternal weight gain, birth
injury, shoulder dystocia, neonatal hypoglycemia, macrosomia, and long-term metabolic
outcomes for the child and mother.
Results. The search identified 14,398 citations and included 97 studies (6 randomized controlled
trials, 63 prospective cohort studies, and 28 retrospective cohort studies).
Prevalence of GDM varied across studies and diagnostic criteria: American Diabetes
Association (75 g) 2 to 19 percent; Carpenter and Coustan 3.6 to 38 percent; National Diabetes
Data Group 1.4 to 50 percent; and World Health Organization 2 to 24.5 percent. Lack of a gold
standard for the diagnosis of GDM and little evidence about the accuracy of screening strategies
for GDM remain problematic. The 50 g oral glucose challenge test with a glucose threshold of
130 mg/dL versus 140 mg/dL improves sensitivity and reduces specificity. Both thresholds have
high negative predictive values (NPV) but variable positive predictive values (PPVs) across a
range of prevalence. There was limited evidence for the screening of GDM diagnosed less than
24 weeks’ gestation (three studies). One study compared the International Association of
Diabetes in Pregnancy Study Groups’ (IADPSG) diagnostic criteria with a two-step strategy.
Sensitivity was 82 percent, specificity was 94 percent.
Only two studies examined the effects on health outcomes from screening for GDM. One
retrospective cohort study (n=1,000) showed more cesarean deliveries in the screened group. A
survey within a prospective cohort study (n=93) found the same incidence of macrosomia (≥4.3
kg) in screened and unscreened groups (7 percent each group).
vi
Thirty-eight studies examined health outcomes for women who met different criteria for
GDM and did not undergo treatment. Methodologically strong studies showed a continuous
positive relationship between increasing glucose levels and the incidence of primary cesarean
section and macrosomia. One of these studies also found significantly fewer cases of
preeclampsia, cesarean section, shoulder dystocia and/or birth injury, clinical neonatal
hypoglycemia, and hyperbilirubinemia for women without GDM compared with those meeting
IADPSG criteria. Among the other studies, fewer cases of preeclampsia were observed for
women with no GDM and women who were false positive versus those meeting Carpenter and
Coustan criteria. For maternal weight gain, few comparisons showed differences. For fetal birth
trauma, single studies showed no differences for women with Carpenter and Coustan GDM and
World Health Organization impaired glucose tolerance versus women without GDM. Women
diagnosed based on National Diabetes Data Group GDM had more fetal birth trauma compared
with women without GDM. Fewer cases of macrosomia were seen in the group without GDM
compared with Carpenter and Coustan GDM, Carpenter and Coustan 1 abnormal oral glucose
tolerance test, National Diabetes Data Group GDM, National Diabetes Data Group false
positives, and World Health Organization impaired glucose tolerance. Fewer cases of neonatal
hypoglycemia were found among patient groups without GDM compared with those meeting
Carpenter and Coustan criteria. There was more childhood obesity for Carpenter and Coustan
GDM versus patient groups with no GDM.
Eleven studies compared diet modification, glucose monitoring, and insulin as needed with
no treatment. Moderate evidence showed fewer cases of preeclampsia in the treated group. The
evidence was insufficient for maternal weight gain and birth injury. Moderate evidence found
less shoulder dystocia with treatment for GDM. Low evidence showed no difference for neonatal
hypoglycemia between treated and untreated GDM. Moderate evidence showed benefits of
treatment for reduction of macrosomia (>4,000 g). There was insufficient evidence for long-term
metabolic outcomes among offspring.
Five studies provided data on harms of treating GDM. No difference was found for cesarean
delivery, induction of labor, small for gestational age, or admission to a neonatal intensive care
unit. There were significantly more prenatal visits among those treated.
Conclusions. While evidence supports a positive association with increasing plasma glucose on
a 75 g or 100 g oral glucose tolerance test and macrosomia and primary cesarean section, clear
thresholds for increased risk were not found. The 50 g oral glucose challenge test has high NPV
but variable PPV. Treatment of GDM results in less preeclampsia and macrosomia. Current
evidence does not show that treatment of GDM has an effect on neonatal hypoglycemia or future
poor metabolic outcomes. There is little evidence of short-term harm from treating GDM other
than an increased demand for services. Research is needed on the long-term metabolic outcome
for offspring as a result of GDM and its treatment, and the “real world” effects of GDM
treatment on use of care.
vii
Contents
Executive Summary ................................................................................................................ ES-1
Introduction ................................................................................................................................... 1
Gestational Diabetes Mellitus ....................................................................................................1
Risk Factors .........................................................................................................................2
Screening and Diagnostic Strategies ....................................................................................2
Treatment Strategies ............................................................................................................8
Scope and Key Questions ..........................................................................................................8
Scope of the Review ............................................................................................................8
Key Questions ......................................................................................................................9
Methods ........................................................................................................................................ 13
Topic Refinement and Technical Expert Panel .......................................................................13
Literature Search Strategy........................................................................................................13
Inclusion and Exclusion Criteria..............................................................................................14
Study Selection ........................................................................................................................14
Quality Assessment of Individual Studies .........................................................................15
Quality Assessment of Diagnostic Studies ........................................................................15
Quality Assessment of Trials .............................................................................................15
Quality Assessment of Cohort Studies ..............................................................................15
Data Extraction ........................................................................................................................16
Data Synthesis ..........................................................................................................................16
Strength of the Body of Evidence ............................................................................................17
Applicability ............................................................................................................................18
Peer Review and Public Commentary .....................................................................................18
Results .......................................................................................................................................... 19
Results of Literature Searches .................................................................................................19
Description of Included Studies ...............................................................................................21
Methodological Quality of Included Studies ...........................................................................21
Key Question 1. What are the sensitivities, specificities, reliabilities, and yields
of current screening tests for GDM? ..................................................................................22
Description of Included Studies .........................................................................................22
Methodological Quality of Included Studies .....................................................................23
Detailed Synthesis ..............................................................................................................25
Key Question 2. What is the direct evidence on the benefits and harms of screening
women for GDM to reduce maternal, fetal, and infant morbidity and mortality? .............40
Description of Included Studies .........................................................................................40
Methodological Quality of Included Studies .....................................................................41
Key Points ..........................................................................................................................41
Detailed Synthesis ..............................................................................................................41
Key Question 3. In the absence of treatment, how do health outcomes of mothers
who meet various criteria for gdm and their offspring compare
to those who do not? ..........................................................................................................42
Description of Included Studies .........................................................................................42
Methodological Quality of Included Studies .....................................................................43
Key Points ..........................................................................................................................43
viii
Detailed Synthesis ..............................................................................................................45
Key Question 4. Does treatment modify the health outcomes of mothers
who meet various criteria for GDM and offspring?...........................................................72
Description of Included Studies .........................................................................................72
Methodological Quality of Included Studies .....................................................................72
Key Points ..........................................................................................................................72
Detailed Synthesis ..............................................................................................................74
Key Question 5. What are the harms of treating GDM and do they vary by
diagnostic approach? ..........................................................................................................90
Description of Included Studies .........................................................................................90
Methodological Quality of Included Studies .....................................................................90
Key Points ..........................................................................................................................90
Detailed Synthesis ..............................................................................................................91
Discussion..................................................................................................................................... 95
Key Findings and Discussion...................................................................................................95
Key Question 1 ..................................................................................................................95
Key Question 2 ..................................................................................................................97
Key Question 3 ..................................................................................................................98
Key Question 4 ................................................................................................................102
Key Question 5 ................................................................................................................104
Findings in Relationship to What Is Already Known ............................................................105
Applicability ..........................................................................................................................106
Limitations of the Evidence Base ..........................................................................................107
Future Research .....................................................................................................................108
Limitations of the Review......................................................................................................109
Conclusions ............................................................................................................................110
References ...................................................................................................................................120
Acronyms and Abbreviations ...................................................................................................130
Tables
Table A. Diagnostic criteria and plasma glucose thresholds for GDM .................................... ES-5
Table B. Relationship between predictive values and prevalence for different
screening tests ....................................................................................................................ES-14
Table C. Strength of evidence for Key Question 4: maternal and infant outcomes ............... ES-18
Table D. Summary of evidence for all Key Questions ........................................................... ES-26
Table 1. Diagnostic criteria and plasma glucose thresholds for GDM ........................................... 5
Table 2. Eligibility criteria for the review .................................................................................... 14
Table 3. Prevalence and diagnostic test characteristics for 50 g OGCT by CC or ADA
(2000–2010) diagnostic criteria .............................................................................................. 28
Table 4. Prevalence and diagnostic test characteristics for 50 g OGCT by NDDG
diagnostic criteria .................................................................................................................... 30
Table 5. Prevalence and diagnostic test characteristics for 50 g OGCT
(different thresholds) by ADA (2000–2010) 75 g criteria ...................................................... 32
Table 6. Prevalence and diagnostic test characteristics for 50 g OGCT by WHO
diagnostic criteria .................................................................................................................... 33
ix
Table 7. Prevalence and diagnostic test characteristics for fasting plasma glucose
by CC/ADA (2000–2010) diagnostic criteria ......................................................................... 35
Table 8. Prevalence and diagnostic test characteristics for fasting plasma glucose
by NDDG-WHO and other diagnostic criteria ....................................................................... 36
Table 9. Prevalence and diagnostic test characteristics for risk factor screening
by different diagnostic criteria ................................................................................................ 37
Table 10. Prevalence and characteristics of other screening tests by GDM
diagnostic criteria .................................................................................................................... 38
Table 11. Prevalence and characteristics of various screening tests for screening
in the first and second trimesters (Maegawa study)................................................................ 39
Table 12. Evidence summary table: maternal outcomes .............................................................. 52
Table 13. Strength of evidence summary table: maternal outcomes ............................................ 55
Table 14. Evidence summary table: fetal/neonatal outcomes ....................................................... 65
Table 15. Strength of evidence summary table: fetal/neonatal outcomes .................................... 70
Table 16. Evidence summary for Key Question 4: maternal outcomes ....................................... 78
Table 17. Evidence summary for Key Question 4: infant outcomes ............................................ 87
Table 18. Strength of evidence for Key Question 4: maternal and infant outcomes .................... 89
Table 19. Evidence summary for Key Question 5 ........................................................................ 94
Table 20. Relationship between predictive values and prevalence for different
screening tests ......................................................................................................................... 97
Table 21. Summary of strength of evidence for the association between different
glucose levels and maternal outcomes (Key Question 3) ....................................................... 99
Table 22. Summary of strength of evidence for the association between different
glucose levels and neonatal/infant outcomes (Key Question 3) ........................................... 101
Table 23. Summary of strength of evidence for benefits of treatment (Key Question 4)........... 104
Table 24. Summary of evidence for all Key Questions .............................................................. 112
Figures
Figure 1. Comparison of different diagnostic thresholds for GDM................................................ 4
Figure 2. Analytic framework for screening and diagnosing GDM ............................................. 12
Figure 3. Flow diagram of study retrieval and selection .............................................................. 20
Figure 4. QUADAS-2 assessment of risk of bias by domain ....................................................... 24
Figure 5. QUADAS-2 assessment of applicability by domain ..................................................... 24
Figure 6. Forest plot of sensitivity and specificity: 50 g OGCT by CC or ADA
(2000–2010) criteria................................................................................................................ 27
Figure 7. Forest plot of sensitivity and specificity: 50 g OGCT by NDDG criteria ..................... 30
Figure 8. Forest plot of sensitivity and specificity: 50 g OGCT (different thresholds)
by ADA (2000–2010) 75 g criteria ......................................................................................... 31
Figure 9. Forest plot of sensitivity and specificity: 50 g OGCT by WHO criteria ....................... 32
Figure 10. Forest plot of sensitivity and specificity: fasting plasma glucose by
CC/ADA (2000–2010) criteria ............................................................................................... 34
Figure 11. Forest plot of sensitivity and specificity: Risk factor screening by different
diagnostic criteria (CC/ADA, NDDG, WHO) ........................................................................ 36
Figure 12. Forest plot of sensitivity and specificity: 75 g OGTT by 100 g OGTT ...................... 40
Figure 13. CC GDM versus no GDM: preeclampsia.................................................................... 47
Figure 14. CC GDM versus false positive: preeclampsia ............................................................. 47
x
Figure 15. NDDG false positive versus no GDM: preeclampsia.................................................. 48
Figure 16. WHO impaired glucose tolerance versus no GDM: preeclampsia .............................. 48
Figure 17. CC GDM versus no GDM: maternal hypertension ..................................................... 48
Figure 18. CC GDM versus false positive: maternal hypertension .............................................. 49
Figure 19. CC 1 abnormal OGTT versus no GDM: maternal hypertension ................................. 49
Figure 20. CC GDM versus no GDM: cesarean delivery ............................................................. 50
Figure 21. CC GDM versus false positive: cesarean delivery ...................................................... 50
Figure 22. CC, 1 abnormal OGTT versus no GDM: cesarean delivery ....................................... 50
Figure 23. CC false positive versus no GDM: cesarean delivery ................................................. 51
Figure 24. NDDG false positive versus no GDM: cesarean delivery ........................................... 51
Figure 25. WHO impaired glucose tolerance versus no GDM: cesarean delivery ....................... 51
Figure 26. CC, 1 abnormal OGTT versus false positive: cesarean delivery................................. 51
Figure 27. CC GDM versus no GDM: macrosomia (>4,000 g) ................................................... 56
Figure 28. CC, 1 abnormal OGTT versus no GDM: macrosomia (>4,000 g) .............................. 57
Figure 29. NDDG false positive versus no GDM: macrosomia (>4,000 g) ................................. 57
Figure 30. CC GDM versus false positive: macrosomia (>4,000 g) ............................................ 57
Figure 31. CC GDM versus 1 abnormal OGTT: macrosomia (>4,000g) ..................................... 57
Figure 32. CC false positives versus no GDM: macrosomia (>4,000 g) ...................................... 58
Figure 33. CC, 1 Abnormal OGTT versus false positives: macrosomia (>4,000 g) .................... 58
Figure 34. IADPSG GDM versus no GDM: macrosomia (>4,000 g) .......................................... 58
Figure 35. CC GDM versus no GDM: macrosomia (>4,500 g) ................................................... 59
Figure 36. CC GDM versus false positive: macrosomia (>4,500 g) ............................................ 59
Figure 37. CC GDM versus no GDM: shoulder dystocia............................................................. 60
Figure 38. CC GDM versus no GDM: hypoglycemia .................................................................. 61
Figure 39. CC, 1 abnormal OGTT versus no GDM: hypoglycemia ............................................. 61
Figure 40. WHO impaired glucose tolerance versus no GDM: hypoglycemia ............................ 61
Figure 41. CC GDM versus no GDM: hyperbilirubinemia .......................................................... 62
Figure 42. WHO impaired glucose tolerance versus no GDM: hyperbilirubinemia .................... 62
Figure 43. CC GDM versus no GDM: morbidity/mortality ......................................................... 63
Figure 44. CC GDM versus false positive: morbidity/mortality .................................................. 63
Figure 45. CC, 1 abnormal OGTT versus no GDM: morbidity/mortality .................................... 63
Figure 46. CC false positive versus no GDM: morbidity/mortality ............................................. 63
Figure 47. NDDG false positive versus no GDM: morbidity/mortality ....................................... 64
Figure 48. WHO IGT versus no GDM: morbidity/mortality........................................................ 64
Figure 49. Effect of treatment on outcomes of women with GDM: cesarean delivery ................ 75
Figure 50. Effect of treatment on outcomes of women with GDM: induction of labor ............... 76
Figure 51. Effect of treatment on outcomes of women with GDM: preeclampsia ....................... 77
Figure 52. Effect of treatment on outcomes of women with GDM: weight gain ......................... 78
Figure 53. Effect of treatment on outcomes for offspring of women with GDM:
birthweight >4,000 g ............................................................................................................... 79
Figure 54. Effect of treatment on outcomes for offspring of women with GDM:
birthweight (continuous) ......................................................................................................... 80
Figure 55. Effect of treatment on outcomes for offspring of women with GDM:
large for gestational age (LGA) .............................................................................................. 80
Figure 56. Effect of treatment on outcomes for offspring of women with GDM:
shoulder dystocia .................................................................................................................... 81
xi
Figure 57. Effect of treatment on outcomes for offspring of women with GDM:
birth trauma ............................................................................................................................. 82
Figure 58. Effect of treatment on outcomes for offspring of women with GDM:
hypoglycemia .......................................................................................................................... 83
Figure 59. Effect of treatment on outcomes for offspring of women with GDM:
hyperbilirubinemia .................................................................................................................. 83
Figure 60. Effect of treatment on outcomes for offspring of women with GDM:
perinatal deaths ....................................................................................................................... 84
Figure 61. Effect of treatment on outcomes for offspring of women with GDM:
respiratory complications ........................................................................................................ 85
Figure 62. Effect of treatment on outcomes for offspring of women with GDM:
APGAR scores, 5 minutes ...................................................................................................... 85
Figure 63. Effect of treatment on adverse effects for infants of mothers with GDM:
Small for gestational age (SGA) ............................................................................................. 91
Figure 64. Effect of treatment on adverse effects for infants of mothers with GDM:
NICU admissions .................................................................................................................... 92
Figure 65. Effect of treatment on outcomes of women with GDM: induction of labor ............... 93
Figure 66. Effect of treatment on outcomes of women with GDM: cesarean delivery ................ 94
Appendixes
Appendix A. Literature Search Strings
Appendix B. Review Forms
Appendix C. Methodological Quality of Included Studies
Appendix D. Evidence Tables
Appendix E. List of Excluded Studies and Unobtained Studies
Appendix F. Key Question 1 HSROC Curves
Appendix G. Adjusted Analyses for KQ3
xii
Executive Summary
Introduction
Gestational Diabetes Mellitus
Gestational diabetes mellitus (GDM) is defined as glucose intolerance first discovered in
pregnancy. Pregestational diabetes mellitus refers to any type of diabetes diagnosed before
pregnancy. Pregnant women with pregestational diabetes experience an increased risk of poor
maternal, fetal, and neonatal outcomes.1 The extent to which GDM predicts adverse outcomes
for mother, fetus, and neonate is less clear.
Depending on the diagnostic criteria used and the population screened, the prevalence of
GDM ranges from 1.1 to 25.5 percent of pregnancies in the United States.2-4 In 2009, the Centers
for Disease Control and Prevention reported a prevalence of 4.8 percent of diabetes in
pregnancy. An estimated 0.5 percent of these cases likely represented women with pregestational
diabetes. Data from the international Hyperglycemia and Adverse Pregnancy Outcome (HAPO)
study3 indicate that 6.7 percent of the women met a fasting plasma glucose threshold of 95
mg/dL (5.3 mmol/L), which is in keeping with the Carpenter and Coustan5 (CC) criteria that are
in common practice in North America. In contrast, 17.8 percent of women were diagnosed with
GDM using the International Association of the Diabetes in Pregnancy Study Groups (IADPSG)
criteria in which lower glucose thresholds diagnose GDM.
The prevalence of GDM is not only influenced by diagnostic criteria but also by population
characteristics. In a recent publication, data from the Hyperglycemia and Adverse Pregnancy
Outcome Study (HAPO) demonstrated wide variability in GDM prevalence across a number of
study centers, both internationally and within the United States, even when the same diagnostic
criteria are applied (i.e., the IADPSG criteria).6 Prevalence in the United States ranged from 15.5
percent in Providence, RI, to 25.5 percent in Bellflower, CA. There are ethnic differences in the
prevalence of GDM in the United States. Native Americans, Asians, Hispanics, and AfricanAmerican women are at higher risk than non-Hispanic white women.7 Data from 2000 showed
that prevalence was highest among Asian and Hispanic women (~7 to 8 percent), intermediate
among African-American women (~6 percent), and lower among non-Hispanic white women
(~5 percent) based on CC criteria and/or hospital discharge diagnosis.7 The rate of increase of
prevalence over the past 10 years has been highest for Asian and African-American women.7
The incidence of GDM has increased over the past decades in parallel with the increase in
rates of obesity and type 2 diabetes mellitus, and this trend is expected to continue.8 It is unclear
how much the increase in obesity will affect the proportion of women diagnosed with overt
diabetes during pregnancy versus transient pregnancy-induced glucose intolerance.
GDM is usually diagnosed after 20 weeks’ gestation when placental hormones that have the
opposite effect of insulin on glucose metabolism increase substantially. Women with adequate
insulin secreting capacity overcome this insulin resistance of pregnancy by secreting more
endogenous insulin to maintain normal blood glucose. Women with less adequate pancreatic
reserve are unable to produce sufficient insulin to overcome the increase in insulin resistance,
and glucose intolerance results.
Glucose abnormalities in women with GDM usually resolve postpartum, but commonly recur
in subsequent pregnancies. Women with GDM have an increased risk of future development of
overt diabetes. The cumulative incidence of diabetes after a diagnosis of GDM varies widely
ES-1
depending on maternal body mass index (BMI), ethnicity, and time since index pregnancy, and it
may reach levels as high as 60 percent.9 When glucose abnormalities persist postpartum in a
woman with GDM, her diabetes is recategorized as overt diabetes. When this occurs, the
likelihood that this woman had pregestational (i.e., overt) diabetes increases, especially if the
diagnosis of GDM occurred before 20 weeks’ gestation and glucose levels were markedly
elevated in pregnancy.
Studies investigating pregnancy outcomes of women with GDM show considerable
variability in the proportion of women with suspected pregestational diabetes. This variability
contributes to the confusion surrounding the true morbidity of GDM. In an attempt to enable
better comparability across future studies and more accurate risk stratification of pregnant
women with diabetes, recommendations10 have proposed that women with more severe glucose
abnormalities in pregnancy be excluded from the diagnosis of GDM. The expectation is that this
would exclude women with overt diabetes from the population of women defined as having
GDM. This proposal is in contrast to the older definition of GDM, which includes any degree of
glucose intolerance first discovered in pregnancy.
Risk Factors
Risk factors for GDM include greater maternal age, higher BMI, member of an ethnic group
at increased risk for development of type 2 diabetes mellitus (i.e., Hispanic, African, Native
American, South or East Asian, or Pacific Islands ancestry), polyhydramnios, past history of
GDM, macrosomia in a previous pregnancy, history of unexplained stillbirth, type 2 diabetes
mellitus in a first degree relative, polycystic ovary syndrome, and metabolic syndrome.11 Low
risk of GDM is usually defined as young (age less than 25 or 30 years), non-Hispanic white,
normal BMI (25 kg/m2 or less), no history of previous glucose intolerance or adverse pregnancy
outcomes associated with GDM, and no first degree relative with known diabetes.7,12 Women at
high risk of GDM are usually defined as having two or more risk factors for GDM. Women at
moderate risk of GDM do not satisfy all criteria of women at low risk, but they lack two or more
risk factors for GDM.
Screening and Diagnostic Strategies
The 2008 U.S. Preventive Services Task Force (USPSTF) evidence review on screening for
GDM concluded that at that time, “evidence was insufficient to assess the balance of benefits and
harms of screening for GDM either before or after 24 weeks’ gestation.”13 The report suggested
that “…until there was better evidence, clinicians should discuss screening for GDM with their
patient and make case-by-case decisions. Discussions should include information about the
uncertainty of benefits and harms as well as the frequency of positive screening test results.”
The 2001 practice guidelines of the American College of Obstetricians and Gynecologists
(ACOG) endorsed risk factor-based screening for GDM, recognizing that low-risk women may
be less likely to benefit from screening with glucose measurements. Women were considered
low risk of GDM if they met all the following criteria: (1) younger than 25 years; (2) not a
member of an ethnic group at high risk for development of type 2 diabetes mellitus; (3) BMI of
25 kg/m2 or less; (4) no history of previous glucose intolerance or adverse pregnancy outcomes
associated with GDM; and (5) no first degree relative with known diabetes. ACOG plans to
update its 2001 practice guidelines on GDM based on the proceedings of the 2012 National
Institutes of Health consensus conference on GDM diagnosis. Until 2011, the American Diabetes
Association (ADA) also endorsed no screening for pregnant woman who met all the criteria
ES-2
mentioned above for low risk of GDM. In 2011 the ADA changed their recommendations to
endorse glucose testing for GDM in all pregnant women who do not have a diagnosis of
pregestational diabetes.
Common practices of glucose screening for GDM in North America involve a two-step
approach in which patients with abnormal results on a screening test receive a subsequent
diagnostic test.14 Typically, a 50 g oral glucose challenge test (OGCT) is initially administered
between 24 and 28 weeks’ gestation in a nonfasting state, in women at moderate risk (i.e.,
women who do not meet all low risk criteria but lack two or more risk factors for GDM). The
test is administered earlier in gestation for women at high risk of GDM (i.e., multiple risk factors
for GDM) and repeated at 24–28 weeks’ gestation if initial surveillance is normal. Patients who
meet or exceed a screening threshold (usually 130 mg/dL or 140 mg/dL) receive a more involved
diagnostic test—the oral glucose tolerance test (OGTT), in which a 75 g or 100 g oral glucose
load is administered in a fasting state, and plasma glucose levels are evaluated after 1, 2, or 3
hours. A diagnosis of GDM is made in pregnant women when one or more glucose values fall at
or above the specified glucose thresholds. Alternatively, a one-step method in which all patients
or high-risk patients forego the screening test and proceed directly to the OGTT has been
recommended.15
The absence of a universally accepted gold standard for the diagnosis of GDM has resulted in
a variety of recommended diagnostic glucose thresholds that have been endorsed by different
stakeholders (Table A). These criteria reflect changes that have occurred in laboratory glucose
measurements over the years and in new evidence that suggests the ability of different glucose
thresholds to predict poor pregnancy outcomes. The different diagnostic criteria and thresholds
result in different estimates of the prevalence of GDM.
In 2004, a cross-sectional study reported that universal screening was the most common
practice in the United States, with 96 percent of obstetricians routinely screening for GDM.16 In
contrast, the guidelines of ACOG and the ADA at that time stated that women at low risk for
GDM were unlikely to benefit from screening.14,17 Since only 10 percent of pregnant women
were categorized as low risk, some argued that selective screening contributed to confusion, with
little benefit and potential for harm.18 Of particular concern was the association between risk
factor-based screening and high rates of false negative results.19 Others have endorsed alternative
risk scoring systems for screening.20
The IADPSG, an international consensus group with representation from multiple obstetrical
and diabetes organizations, recently spearheaded a reexamination of the definition of GDM in an
attempt to bring uniformity to GDM diagnoses.21 The IADPSG recommended that a one-step 75
g OGTT be given to all pregnant women who do not have a diagnosis of overt diabetes. They
also recommended that a single glucose value, rather than at least two abnormal values at or
above diagnostic glucose thresholds on the OGTT be accepted as sufficient for a diagnosis of
GDM. The diagnostic glucose thresholds recommended by the IADPSG were the maternal
glucose values from the HAPO study3 that identified a 1.75-fold increase (adjusted odds ratio
relative to the mean cohort glucose values) in large for gestational age, elevated C-peptide, high
neonatal body fat, or in a combination of these factors. Since overt diabetes is often
asymptomatic, may not have been screened for before conception, has a prevalence that is
increasing dramatically in reproductive-age women, and carries a higher risk for poor pregnancy
outcomes,22 the IADPSG also recommended that all women, or at least women from high-risk
groups for type 2 diabetes mellitus, be screened for overt diabetes at their first prenatal visit and
excluded from the diagnosis of GDM using one of the following criteria: fasting plasma glucose
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≥126 mg/dL (7.0 mmol/L), glycated hemoglobin (HbA1c) ≥6.5 percent (Diabetes Chronic
Complications Trial/United Kingdom Prospective Diabetes Study standardized), or a random
plasma glucose ≥200 mg/dL (11.1 mmol/L) confirmed by one of the first two measures.
Treatment Strategies
Initial treatment for GDM involves diet modification, glucose monitoring, and moderate
exercise. When dietary management does not achieve desired glucose control, insulin or oral
antidiabetic medications may be used.23 Increased prenatal surveillance may also occur as well as
changes in delivery management depending on fetal size and the effectiveness of measures to
control glucose.
Scope of the Review
Based on systematic reviews published in 2003 and 2008, the USPSTF concluded that there
was insufficient evidence upon which to make a recommendation regarding routine screening of
all pregnant women for GDM.13,24 Several key studies have been published since the 2008
USPSTF evidence report.3,8,25 The National Institutes of Health’s Office of Medical Applications
of Research (OMAR) commissioned this report (specifically Key Questions 3 to 5, see section
below), which the Agency for Healthcare Research and Quality (AHRQ) Evidence-based
Practice Center (EPC) Program conducted. OMAR will use the review to inform members of
consensus meetings and inform guideline development. The USPSTF joined this effort and will
use the review to update its recommendation on screening for GDM (Key Questions 1 and 2).
The primary aims of this review were to (1) identify the test properties of screening and
diagnostic tests for GDM, (2) evaluate the potential benefits and harms of screening at ≥24
weeks and <24 weeks’ gestation, (3) assess the effects of different screening and diagnostic
thresholds on outcomes for mothers and their offspring, and (4) determine the effects of
treatment in modifying outcomes for women diagnosed with GDM. The benefits and harms of
treatments were considered in this review to determine the downstream effects of screening on
health outcomes. The intent of this review was also to assess whether evidence gaps in the
previous USPSTF reviews have been filled. These gaps included lack of sufficient evidence to
determine whether maternal or fetal complications are reduced by screening; lack of screening
studies with adequate power to evaluate health outcomes such as mortality, neonatal intensive
care unit (NICU) admissions, hyperbilirubinemia; limited evidence on the accuracy of screening
strategies; and insufficient evidence on the benefits of treating GDM in improving health
outcomes.
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Table A. Diagnostic criteria and plasma glucose thresholds for gestational diabetes mellitus
Year
Organization
ADA
ADA
Low risk† excluded
IADPSG
ADA
1. CC
th
2. 4 IWC (same)
th
3. 5 IWC (same as
th
4 but 75 g accepted
with same glucose
thresholds)
1999
26
2000-2010
2011
Abnormal
Value(s)
50 g OGCT
1
100 g OGTT
2 or more
50 g OGCT
1
0 (h)
—
105 mg/dL
5.8 mmol/L
—
10,27-36
37
5
1. 1982
38
2. 1998
39
3. 2007
40
NDDG
1979
WHO
1999 WHO
41
consultation
WHO
Testing
Schedule
1985 WHO
study group
42
report
100 g or 75 g
OGTT after
overnight fast
≥8hr
Threshold (Equal to or Greater Than)
1 (h)
2 (h)
140 mg/dL
—
7.8 mmol/L
190 mg/dL
165 mg/dL
10.5 mmol/L
9.1 mmol/L
130 mg/dL
7.2 mmol/L
or
—
140 mg/dL
7.8 mmol/L
3 (h)
—
145 mg/dL
8.0 mmol/L
—
140 mg/dL
7.8 mmol/L
(3 hr value only
for 100 g test)
2 or more
95 mg/dL
5.3 mmol/L
180 mg/dL
10.0 mmol/L
155 mg/dL
8.6 mmol/L
75 g OGTT
1 or more
92 mg/dL
5.1 mmol/L
153 mg/dL
8.5 mmol/L
50 g OGCT
1
180 mg/dL
10.0 mmol/L
130 mg/dL
7.2 mmol/L
100 g OGTT
2 or more
95 mg/dL
5.3 mmol/L
180 mg/dL
10.0 mmol/L
155 mg/dL
8.6 mmol/L
140 mg/dL
7.8 mmol/L
—
105 mg/dL
5.8 mmol/L
—
190 mg/dL
10.5 mmol/L
—
165 mg/dL
9.1 mmol/L
140 mg/dL
7.8 mmol/L for
IGT of pregnancy;
200 mg/dL
11.1 mmol/L for
Dx of DM
7.8 mmol/L (140
mg/dL); for IGT of
pregnancy; 200
(11.1 mmol/L) for
Dx of DM
—
145 mg/dL
8.0 mmol/L
50 g OGCT
100 g OGTT
75 g OGTT
75 g OGTT
—
—
2 or more
1
6.1 mmol/L for
IGT of
pregnancy;
7.0 mmol/L for
Dx of DM
—
1
7.8 mmol/L
140 mg/dL for
IGT of
pregnancy
—
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—
—
—
—
—
Table A. Diagnostic criteria and plasma glucose thresholds for gestational diabetes mellitus (continued)
Organization
CDA
ACOG – risk factor
th
4 IWC
rd
3 IWC
ADIPS
Testing
Schedule
Year
2003, 2008
2001
1991
1998
43,44
Abnormal
Value(s)
50 g OGCT
1
75 g
2 or more
50 g
1
100 g CC
2 or more
100 g NDDG
2 or more
100 g OGTT
2 or more
50 g or 75 g
nonfasting
1
75 g fasting
1
0 (h)
—
95 mg/dL
5.3 mmol/L
—
14,45
46
95 mg/dL
5.3 mmol/L
105 mg/dL
5.8 mmol/L
105 mg/dL
5.8 mmol/L
—
47
99 mg/dL
5.5 mmol/L
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Threshold (Equal to or Greater Than)
1 (h)
2 (h)
140 mg/dL
7.8 mmol/L
or
—
186 mg/dL,
10.3 mmol/L Dx
GDM
191 mg/dL
160 mg/dL
10.6 mmol/L
8.9 mmol/L
130 mg/dL
7.2 mmol/L
or
—
140 mg/dL
7.8 mmol/L
180 mg/dL
155 mg/dL
10.0 mmol/L
8.5 mmol/L
190 mg/dL
165 mg/dL
10.5 mmol/L
9.1 mmol/L
190 mg/dL
165 mg/dL
10.5 mmol/L
9.1 mmol/L
140 mg/dL
7.8 mmol/L (50 g)
or
—
144 mg/dL
8.0 mmol/L (75 g)
144 mg/dL
8.0 mmol/L
or
—
162 mg/dL
9.0 mmol/L*
3 (h)
—
—
—
140 mg/dL
7.8 mmol/L
145 mg/dL
8.0 mmol/L
145 mg/dL
8.0 mmol/L
—
—
Table A. Diagnostic criteria and plasma glucose thresholds for gestational diabetes mellitus (continued)
Threshold (Equal to or Greater Than)
1 (h)
2 (h)
3 (h)
162 mg/dL
48
EASD
1996
75 g
1
—
—
9.0 mmol/L
130 mg/dL
7.2 mmol/L
Risk assessment
or
—
—
1
—
USPSTF (Grade 1
50 g OGCT
2008‡
140 mg/dL
recommendation)
7.8 mmol/L
100 g OGTT
2 or more
NR
NR
NR
NR
ACOG = American College of Obstetricians and Gynecologists; ADA = American Diabetes Association; ADIPS = Australasian Diabetes in Pregnancy Society; CC = Carpenter,
Coustan; CDA = Canadian Diabetes Association; DM = diabetes mellitus; Dx = diagnosis; EASD = European Association for the Study of Diabetes; GDM = gestational diabetes
mellitus; IADPSG = International Association of Diabetes in Pregnancy Study Groups; IGT = impaired glucose tolerance; IWC = International Workshop Conference; NDDG =
National Diabetes Data Group; NR = not reported; OGCT = oral glucose challenge test; OGTT = oral glucose tolerance test; USPSTF = U.S. Preventive Services Task Force;
WHO = World Health Organization
†Low risk defined as age <25 yr, normal body weight, no first degree relative with DM, no history of abnormal glucose, no history of poor obstetrical outcomes, not of high risk
ethnicity for DM.
*in New Zealand.
‡ Screening for GDM: USPSTF recommendation statement Ann Intern Med 2008;148(10):759-65.
Organization
Year
Testing
Schedule
Abnormal
Value(s)
0 (h)
108 mg/dL
6.0 mmol/L
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Key Questions
OMAR and USPSTF developed the Key Questions for this evidence synthesis to inform
members of consensus meetings and inform guideline development; OMAR specifically
developed Key Questions 3 to 5. Investigators from the University of Alberta EPC worked in
consultation with representatives from the AHRQ EPC Program, OMAR and the USPSTF, and a
panel of Technical Experts to operationalize the Key Questions. The Technical Expert Panel
provided content and methodological expertise throughout the development of this evidence
synthesis. Participants in this panel are identified in the front matter of this report. The Key
Questions are as follows:
Key Question 1: What are the sensitivities, specificities, reliabilities, and yields of current
screening tests for GDM? (a) After 24 weeks’ gestation? (b) During the first trimester and up to
24 weeks’ gestation?
Key Question 2: What is the direct evidence on the benefits and harms of screening women
(before and after 24 weeks’ gestation) for GDM to reduce maternal, fetal, and infant morbidity
and mortality?
Key Question 3: In the absence of treatment, how do health outcomes of mothers who meet
various criteria for GDM and their offspring compare to those who do not meet the various
criteria?
Key Question 4: Does treatment modify the health outcomes of mothers who meet various
criteria for GDM and their offspring?
Key Question 5: What are the harms of treating GDM and do they vary by diagnostic approach?
Methods
Literature Search
We systematically searched the following bibliographic databases for studies published from
1995 to May 2012: MEDLINE® Ovid, Ovid MEDLINE® In-Process & Other Non-Indexed
Citations, Cochrane Central Register of Controlled Trials (contains the Cochrane Pregnancy and
Childbirth Group, which hand searches journals pertinent to its content area and adds relevant
trials to the registry), Cochrane Database of Systematic Reviews (CDSR), Database of Abstracts
of Reviews of Effects (DARE), Global Health, Embase, Pascal CINAHL Plus with Full Text
(EBSCO host), BIOSIS Previews® (Web of KnowledgeSM), Science Citation Index Expanded®
and Conference Proceedings Citation Index- Science (both via Web of ScienceSM), PubMed®,
LILACS (Latin American and Caribbean Health Science Literature), National Library of
Medicine (NLM) Gateway, and OCLC ProceedingsFirst and PapersFirst. We searched trial
registries, including the WHO International Clinical Trials Registry Platform (ICTRP),
ClinicalTrials.gov, and Current Controlled Trials. We limited the search to trials and cohort
studies published in English.
We searched the Web sites of relevant professional associations and research groups,
including the ADA, IADPSG, International Symposium of Diabetes in Pregnancy, and Diabetes
ES-8
in Pregnancy Society for conference abstracts and proceedings from the past 3 years. We
reviewed the reference lists of relevant reviews (including the 2008 USPSTF review) and studies
that were included in this report.
Study Selection
Two reviewers independently screened the titles and abstracts using broad inclusion criteria.
We retrieved the full text of articles classified as “include” or “unclear.” Two reviewers
independently assessed each full-text article using a priori inclusion criteria and a standardized
form. We resolved disagreements by consensus or third-party adjudication.
We included published randomized controlled trials (RCTs), nonrandomized controlled trials
(NRCTs), and prospective and retrospective cohort studies. For Key Question 1, we excluded
retrospective cohort studies. We included studies of pregnant women ≥24 weeks’ gestation or
<24 weeks’ gestation, with no known history of preexisting diabetes. Comparisons of interest
varied by Key Question and were as follows: Key Question 1 – any GDM screening or
diagnostic test compared with any GDM reference standard or other screening or diagnostic test;
Key Question 2 – any GDM screening versus no GDM screening; Key Question 3 – women who
met various thresholds for GDM versus those who did not meet various criteria for GDM, where
women in both groups did not receive treatment; Key Questions 4 and 5 – any treatment for
GDM, including but not limited to dietary advice, blood glucose monitoring, insulin therapy (all
preparations), and oral hypoglycemic agents versus no treatment. Studies meeting these
eligibility criteria were included if they reported data for at least one outcome specified in the
Key Questions. We included studies regardless of setting and duration of followup.
Quality Assessment
Two reviewers independently assessed the methodological quality of studies and resolved
discrepancies by discussion and consensus. For Key Question 1, we used the QUADAS-2
checklist49 to assessthe quality of diagnostic accuracy studies. We assessed the internal validity
of RCTs and NRCTs using the Cochrane Collaboration Risk of Bias tool. For cohort studies, we
used the Newcastle-Ottawa Scale. For Key Questions 2 to 5, we summarized the quality of
individual studies as “good,” “fair,” or “poor” based on criteria specific to each tool.
Data Extraction and Synthesis
One reviewer extracted data using a standardized form, and a second reviewer checked the
data for accuracy and completeness. We extracted information on study characteristics, inclusion
and exclusion criteria, participant characteristics, details of the interventions or
diagnostic/screening tests (as appropriate), and outcomes. Reviewers resolved discrepancies by
consensus or in consultation with a third party.
For each Key Question, we presented evidence tables detailing each study and provided a
qualitative description of results. For Key Question 1, we constructed 2x2 tables and calculated
sensitivity, specificity, positive and negative predictive values, reliability (i.e., accuracy), and
yield (i.e., prevalence) of the screening or diagnostic tests. If studies were clinically
homogenous, we pooled sensitivities and specificities using a hierarchical summary receiveroperator curve and bivariate analysis of sensitivity and specificity.50 For the other Key
Questions, we combined studies in a meta-analysis if the study design, population, comparisons,
and outcomes were sufficiently similar. Results were combined using random effects models.
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We quantified statistical heterogeneity using the I-squared (I2) statistic. When I2 was greater than
75 percent, we did not pool results, and we investigated potential sources of heterogeneity.
Strength of the Body of Evidence
Two independent reviewers graded the strength of the evidence for Key Questions 3 and 4
using the EPC GRADE (Grading of Recommendations Assessment, Development and
Evaluation) approach and resolved discrepancies by discussion and consensus. We graded the
evidence for the following key outcomes: birth injury, preeclampsia, neonatal hypoglycemia,
maternal weight gain, and long-term metabolic outcomes of the child and mother. We made a
post hoc decision to grade shoulder dystocia and macrosomia. These were not included in the
protocol as outcomes that would be graded but were felt by the clinical investigators to be
important to grade during the course of preparing the review. For each outcome, we assessed
four major domains: risk of bias (rated as low, moderate, or high), consistency (rated as
consistent, inconsistent, or unknown), directness (rated as direct or indirect), and precision (rated
as precise or imprecise). The overall strength of evidence was graded as high, moderate, low, or
insufficient.
Applicability
We assessed the applicability of the body of evidence following the PICOTS (population,
intervention, comparator, outcomes, timing of outcome measurement, and setting) format used to
assess study characteristics. Factors that may potentially limit applicability were discussed.
Peer Review and Public Commentary
Peer reviewers were invited to provide written comments on the draft report based on their
clinical, content, or methodologic expertise. Peer reviewer comments on the draft report were
addressed by the EPC in preparation of the final draft of the report. Peer reviewers do not
participate in writing or editing of the final report or other products. The synthesis of the
scientific literature presented in the final report does not necessarily represent the views of
individual reviewers. The dispositions of the peer review comments are documented and will be
published 3 months after the publication of the Evidence Report.
Potential reviewers must disclose any financial conflicts of interest greater than $10,000 and
any other relevant business or professional conflicts of interest. Invited peer reviewers may not
have any financial conflict of interest greater than $10,000. Peer reviewers who disclose
potential business or professional conflicts of interest may submit comments on draft reports
through AHRQ’s public comment mechanism.
Results
Description of Included Studies
The search identified 14,398 citations, and 97 studies were included: 6 RCTs, 63 prospective
cohort studies, and 28 retrospective cohort studies. The studies were published between 1995 and
2012 (median 2004). Studies were conducted in the United States (24 percent), Europe (23
percent), Asia (22 percent), the Middle East (20 percent), Australia (4 percent), Central and
South America (3 percent), and Canada (4 percent). The number of women enrolled in each
study ranged from 32 to 23,316 (median 750). The mean age of study participants was 30 years.
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Forty-eight studies (50 percent) analyzed women tested for GDM between 24 and 28 weeks,
with an OGCT taking place first and the OGTT following within 7 days. Thirty-one studies (32
percent) did not specify when screening or diagnostic procedures took place. Eighteen studies
(18 percent) screened or tested within unique time ranges. Of these, one study screened
participants with an OGCT at 21–23 weeks followed by a diagnostic OGTT at 24–28 weeks;
another screened a group of participants after 37 weeks; one study screened before 24 weeks;
another screened women at risk between 14 and 16 weeks, with normal women screened at the
usual 24–28 weeks; and one study screened between 16 and 20 weeks or between 17 and 21
weeks followed by a diagnostic OGTT at 26–32 weeks. Remaining studies generally provided
broader screening times ranging from 21 to 32 weeks’ gestation. Studies employing WHO
criteria generally screened further into gestation as only an OGTT was performed: one study
screened at 28–32 weeks, and another study screened women at high risk at 18–20 weeks and
others at 28–30 weeks.
Methodological Quality of Included Studies
The methodological quality was assessed using different tools depending on the Key
Question and study design: QUADAS-2 was used for Key Question 1; for Key Questions 2 to 5,
the Cochrane Risk of Bias tool was used for RCTs and the Newcastle Ottawa Scale was used for
cohort studies. The methodological quality of studies is summarized for each Key Question
below.
Results of Included Studies
The results are presented by Key Question in the sections that follow. A summary of the
results for all Key Questions is provided in Table D at the end of the Executive Summary.
Key Question 1
Fifty-one studies provided data for Key Question 1, which examined the diagnostic test
characteristics and prevalence of current screening and diagnostic tests for GDM. Studies were
conducted in a range of geographic regions: 11 in North America, 10 in Europe, 12 in Asia, 15 in
the Middle East, 2 in South America, and 1 in Australia. Studies reported on findings for a
number of screening tests, including the 50 g OGCT, fasting plasma glucose (FPG), and risk
factor-based screening, as well as other, less common tests such as HbA1c, serum fructosamine,
and adiponectin. GDM was confirmed using criteria developed by different groups, including
CC, ADA, National Diabetes Data Group (NDDG), and WHO. The lack of a gold standard to
confirm a diagnosis of GDM limits the ability to compare the results of studies that have used
different diagnostic criteria. Different criteria result in different rates of prevalence, regardless of
similarities across study settings and patient characteristics. A summary of the results is provided
in Table D.
Methodological quality of the studies was assessed using the QUADAS-2 tool. The domain
of patient selection was rated as low risk for 53 percent and unclear risk for 22 percent of the
studies. Overall, 55 percent were assessed as having high concerns about applicability for this
domain. This was primarily because these studies were conducted in developing countries and
used the WHO criteria to diagnose GDM. The domain of the index test was generally rated as
low risk of bias (53 percent). Concern about applicability was assessed as low (82 percent). The
domain of the reference standard (i.e., the criteria used to confirm a diagnosis of GDM) was
rated as high or unclear risk (80 percent). For most studies, the result of the screening test was
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used to determine whether patients underwent further testing for GDM (lack of blinding) or it
was unclear. Concern about applicability for this domain was assessed as low (84 percent). The
domain of flow and timing was assessed as low risk of bias in 39 percent of studies. However, 35
percent were assessed as unclear risk of bias because not all patients received a confirmatory
reference standard if the screening test was below a certain threshold, so there is a risk of
diagnostic review bias.
Nine studies provided data to estimate sensitivity and specificity of a 50 g OGCT (cutoff
≥140 mg/dL); GDM was confirmed using a 100 g, 3-hour OGTT using CC criteria. Sensitivity
and specificity were 85 percent (95% CI, 76 to 90) and 86 percent (95% CI, 80 to 90),
respectively. Prevalence ranged from 3.8 to 31.9 percent. When prevalence was less than 10
percent, PPV ranged from 18 to 27 percent; when prevalence was 10 percent or more, PPV
ranged from 32 to 83 percent. The median NPV for all studies was 98 percent.
Six studies reported results for a 50 g OGCT (cutoff ≥130 mg/dL); GDM was confirmed
using the CC criteria. Sensitivity was 99 percent (95% CI, 95 to 100) and specificity was 77
percent (95% CI, 68 to 83). Prevalence ranged from 4.3 to 29.8 percent. When prevalence was
less than 10 percent, PPV ranged from 11 to 27 percent; when prevalence was 10 percent or
more, PPV ranged from 31 to 62 percent. The median NPV for all studies was 100 percent.
One study assessed a 50 g OGCT with a cutoff value of ≥200 mg/dL; GDM was confirmed
using the CC criteria. Prevalence was 6.4 percent. Sensitivity, specificity, PPV and NPV were all
100 percent.
The evidence showed that the 50 g OGCT with the 130 mg/dL cutpoint had higher sensitivity
when compared with the 140 mg/dL cutpoint; however, specificity was lower. Both thresholds
have high NPVs, but variable PPVs across a range of GDM prevalence. The Toronto Trihospital
study found evidence to support the use of the lower screening cutpoint for higher risk patients,
and the higher screening cutpoint for lower risk patients.12
Seven studies assessed a 50 g OGCT (≥140 mg/dL); GDM was confirmed using the NDDG
criteria. Sensitivity was 85 percent (95% CI, 73 to 92) and specificity was 83 percent (95% CI,
78 to 87). Prevalence ranged from 1.4 to 45.8 percent. When prevalence was less than 10
percent, PPV ranged from 12 to 39 percent; prevalence was more than 10 percent in one study
and PPV was 57 percent. The median NPV for all studies was 99 percent. Three studies that
assessed a 50 g OGCT (≥130 mg/dL) using NDDG were not pooled. Prevalence ranged from
16.7 to 35.3 percent. PPV ranged from 20 to 75 percent; NPV ranged from 86 to 95 percent.
Three studies assessed a 50 g OGCT (different thresholds); GDM was confirmed using the
ADA 2000-2010 75 g, 2 hour criteria. Sensitivity ranged from 86 to 97 percent; specificity
ranged from 79 to 87 percent. Prevalence ranged from 1.6 to 4.1 percent. PPV ranged from 7 to
20 percent; NPV ranged from 99 to 100 percent.
Three studies assessed a 50 g OGCT (≥140 mg/dL) with GDM confirmed using the WHO 75
g criteria. Sensitivity was 43 to 85 percent and specificity was 73 to 94 percent. Prevalence
ranged from 3.7 to 15.7. In two studies with prevalence less than 10 percent, PPV was 18 and 20
percent; in one study in which prevalence was 10 or more, PPV was 58 percent. The median
NPV for all studies was 99 percent.
Seven studies assessed FPG to screen for GDM; GDM was confirmed using CC criteria.
Four FPG thresholds were compared— ≥85 mg/dL: sensitivity was 87 percent (95% CI, 81 to
91) and specificity was 52 percent (95% CI, 50 to 55); ≥90 mg/dL: sensitivity was 77 percent
(95% CI, 66 to 85) and specificity was 76 percent (95% CI, 75 to77); ≥92 mg/dL: sensitivity was
76 percent (95% CI, 55 to 91) and specificity 92 percent (95% CI, 86 to 96); ≥95 mg/dL:
ES-12
sensitivity was 54 percent (95% CI, 32 to 74) and specificity was 93 percent (95% CI, 90 to 96).
While the effect on health outcomes was not part of this Key Question, the Toronto Trihospital
and HAPO studies demonstrated the ability of using fasting glucose to predict GDM outcomes.
Limited data support the use of HbA1c as a screening test. One study conducted in the
United Arab Emirates using an HbA1c value of 5.5 percent or more lacked specificity (21
percent) despite good sensitivity (82 percent). A study conducted in Turkey showed that an
HbA1c cutoff of 7.2 percent or more had 64 percent sensitivity and specificity. HbA1c does not
perform as well as the 50 g OGCT as a screening test for GDM. However, when HbA1c is
markedly elevated, this supports a possible diagnosis of overt diabetes discovered in pregnancy.
Since 2011–2012, the ADA has endorsed the use of an HbA1c of 6.5 percent or more as
diagnostic of diabetes in nonpregnant women.36
Although eight studies examined risk factors for screening women, our review did not
identify compelling evidence for or against risk factor-based screening. Studies used different
diagnostic criteria and could not be pooled. Sensitivity and specificity varied widely across
studies.
Only three studies included women who were in their first trimester of pregnancy, and they
used different diagnostic criteria. Therefore, no conclusions can be made about the test
characteristics of the screening tests for this group of women.
Four studies compared the 75 g and 100 g load tests, but they were conducted in different
countries and used different criteria or thresholds. The prevalence of GDM ranged from 1.4 to 50
percent. Sensitivity and specificity varied widely across studies. Limited data are available to
draw conclusions about the effectiveness of the different options for diagnostic testing for GDM.
However, because both the 75 g and 100 g load tests are positively linked with outcomes3,51 and
the 75 g test is less time consuming, the adoption of the 75 g glucose load may be warranted,
even if thresholds continue to be debated.3,51
The IADPSG has proposed the elimination of a screening test in favor of proceeding directly
to a diagnostic test for GDM. We identified only one study that compared the IADPSG criteria
with the Australasian Diabetes in Pregnancy Society (two-step) criteria. The sensitivity was 82
percent (95% CI: 74 to 88) and specificity was 94 percent (95% CI: 93 to 96); the PPV and NPV
were 61 percent (95% CI: 53 to 68) and 98 (95% CI: 97 to 99), respectively.
Prevalence and Predictive Values
The prevalence of GDM varied across studies and the diagnostic criteria used. Factors
contributing to the variability included differences in study setting (i.e., country), screening
practices (e.g., universal vs. selective), and population characteristics (e.g., race/ethnicity, age,
BMI).
The predictive value of a screening or diagnostic test is determined by the test’s sensitivity
and specificity and by the prevalence of GDM. Table B presents a series of scenarios that
demonstrate the changes in PPV and NPV for three levels of prevalence (7 percent, 15 percent,
and 25 percent).6 Separate tables are presented for different screening and diagnostic criteria.
The higher the prevalence of GDM, the higher the PPV, or the more likely a positive result is
able to predict the presence of GDM. When the prevalence of GDM is low, the PPV is also low,
even when the test has high sensitivity and specificity. Generally the NPV (negative result rules
out GDM) is very high—98 percent or better at a GDM prevalence of 7 percent.
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Table B. Relationship between predictive values and prevalence for different screening tests
Screening Test
Prevalence
Positive
Predictive
Value
Negative
Predictive Value
50 g OGCT ≥140 mg/dL
by CC/ADA (2000-2010)
Sensitivity=85%;
Specificity=86%
7%
31%
99%
15%
52%
97%
25%
67%
95%
50 g OGCT ≥130 mg/dL
by CC/ADA (2000-2010)
Sensitivity=99%;
Specificity=77%
7%
24%
100%
15%
43%
100%
25%
59%
100%
7%
27%
99%
15%
47%
97%
25%
63%
94%
7%
16%
99%
15%
31%
97%
25%
46%
94%
7%
29%
99%
15%
49%
98%
25%
65%
95%
7%
24%
98%
15%
42%
95%
25%
58%
92%
7%
12%
98%
15%
24%
96%
25%
38%
92%
50 g OGCT ≥140 mg/dL
by NDDG
Sensitivity=85%;
Specificity=83%
50 g OGCT ≥130 mg/dL
by NDDG
Sensitivity=88%;
Specificity=66%
(median)
50 g OGCT ≥140 mg/dL
by ADA 75 g
Sensitivity=88%;
Specificity=84%
(median)
50 g OGCT ≥140 mg/dL
by WHO
Sensitivity=78%;
Specificity=81%
(median)
FPG (≥85 mg/dL) by
CC/ADA (2000-2010)
Sensitivity = 87%;
Specificity = 52%
Risk factor screening by
7%
21%
98%
various criteria
15%
38%
96%
Sensitivity=84%;
Specificity=72%
25%
54%
93%
(median)
ADA = American Diabetes Association; CC = Carpenter-Coustan; FPG = fasting plasma glucose;
NDDG = National Diabetes Data Group; OGCT = oral glucose challenge test; WHO =World Health Organization
Key Question 2
Only two retrospective cohort studies were relevant to Key Question 2, which asked about
the direct benefits and harms of screening for GDM. One retrospective cohort study (n=1,000)
conducted in Thailand showed a significantly greater incidence of cesarean deliveries in the
screened group. A survey of a subset of participants (n=93) in a large prospective cohort study
involving 116,678 nurses age 25–42 years in the United States found the incidence of
macrosomia (infant weight ≥ 4.3 kg) was the same in the screened and unscreened groups (7
percent each group).
No RCTs were available to answer questions about screening. There is a paucity of evidence
on the effect of screening women for GDM on health outcomes. The comparison for this
question was women who had and had not undergone screening. Since screening is now
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commonplace it may be unlikely to identify studies or cohorts in which this comparison is
feasible.
Key Question 3
Thirty-eight studies provided data for Key Question 3, which sought to examine health
outcomes for women who met various criteria for GDM and did not receive treatment. A
summary of the results is provided in Table D. The majority of data came from cohort studies or
the untreated groups from RCTs. Study quality was assessed using the Newcastle-Ottawa Scale
with a possible total of nine stars. The median quality score was 9 out of 9 stars. Studies
receiving lower scores most often did not control for potential confounding, and/or had an
important proportion of patients lost to followup. Overall, the majority of studies were
considered good quality (36 of 38, 95 percent).
A wide variety of diagnostic criteria and thresholds were compared across the studies. The
most common groups reported and compared were GDM diagnosed by CC criteria, no GDM by
any criteria (normal), impaired glucose tolerance defined as one abnormal glucose value, and
false positive (positive OGCT, negative OGTT). Only single studies contributed data for many
of the comparisons and outcomes; therefore, results that showed no statistically significant
differences between groups cannot be interpreted as equivalence between groups, and they do
not rule out potential differences.
Two studies did not group women according to criteria (as above) but examined glucose
levels as a continuous outcome and their association with maternal and neonatal outcomes. Both
studies were methodologically strong. A continuous positive association was found between
maternal glucose and birthweight (both studies), as well as fetal hyperinsulinemia (one study
only). There was some evidence of an association between glucose levels and primary cesarean
section and neonatal hypoglycemia, although the associations were not consistently significant.
No clear glucose thresholds were found that were predictive of poor outcomes. One of these
studies also found significantly fewer cases of preeclampsia, cesarean section, shoulder dystocia
and/or birth injury, clinical neonatal hypoglycemia, and hyperbilirubinemia for women with no
GDM compared with those meeting IADPSG criteria.
For maternal outcomes among the studies that compared groups as described above, women
without GDM and those testing false positive showed fewer cases of preeclampsia than those
meeting CC criteria. No differences in preeclampsia were found for other comparisons, although
evidence was based on few studies per comparison.
Fewer cases of cesarean section were found among women without GDM compared with
women meeting criteria for CC GDM, CC 1 abnormal OGTT, CC false positives, NDDG false
positives, NDDG 1 abnormal oral glucose tolerance test, WHO IGT, IADPSG impaired fasting
glucose (IFG), and IADPSG impaired glucose tolerance (IGT) IFG. There were fewer cases of
cesarean section among false positives compared with women meeting criteria for CC GDM. For
12 other comparisons, there were no differences in rates of cesarean delivery.
For maternal hypertension, significant differences were found for 8 of 16 comparisons; many
comparisons were based on single studies. No GDM groups showed lower incidence of maternal
hypertension when compared with CC GDM, CC 1 abnormal OGTT, IADPSG IFG, IADPSG
IGT-2 (double-impaired glucose tolerance), and IADPSG IGT IFG. Other comparisons showing
significant differences were CC GDM versus false positives (lower incidence for false positives),
IADPSG IGT versus IGT IFG (lower incidence for IGT), and IADPSG IFG versus IGT IFG
(lower incidence for IFG).
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Based on single studies, no differences were observed for maternal birth trauma for three
comparisons. For maternal weight gain (less weight gain considered beneficial), significant
differences were found for 3 of 12 comparisons: IADPSG IGT versus no GDM (favored IGT),
IADPSG IFG versus no GDM (favored IFG), IADPSG IGT-2 versus no GDM (favored IGT-2).
All comparisons were based on single studies. For maternal mortality/morbidity, single studies
contributed to three comparisons, and no differences were found except for fewer cases among
patient groups with no GDM compared with IADPSG GDM. No studies provided data on longterm maternal outcomes, such as type 2 diabetes mellitus, obesity, and hypertension.
The most commonly reported outcome for the offspring was macrosomia >4,000 g. Six of 11
comparisons showed a significant difference: there were fewer cases in the group without GDM
compared with CC GDM, CC 1 abnormal OGTT, NDDG GDM (unrecognized), NDDG false
positives, and WHO IGT. Fewer cases were found for women with false-positive results
compared with CC GDM. Data for macrosomia >4,500 g were available for four comparisons
and showed significant differences in two comparisons: patient groups with no GDM had fewer
cases compared with women with CC GDM and with unrecognized NDDG GDM.
For shoulder dystocia, significant differences were found for 7 of 17 comparisons; all but one
comparison were based on single studies. Patient groups with no GDM showed lower incidence
of shoulder dystocia when compared with CC GDM (5 studies), NDDG GDM (unrecognized),
NDDG false positive, WHO IGT, IADPSG IFG, and IADPSG IGT IFG. The other significant
difference showed lower incidence among the false-positive group compared with CC 1
abnormal OGTT.
For fetal birth trauma or injury, four studies compared CC GDM, NDDG GDM, and WHO
IGT with patient groups without GDM. No differences were observed except for NDDG GDM,
which favored the group with no GDM. Only one difference was found for neonatal
hypoglycemia, with fewer cases among patient groups without GDM compared with those
meeting CC criteria. There were 16 comparisons for hyperbilirubinemia; the majority were based
on single studies. Three comparisons showed significant differences between groups: patient
groups with no GDM had fewer cases compared with CC false positive, IADPSG IGT, and
IADPSG IGT-2, respectively. No differences were found for fetal morbidity/mortality for any of
eight comparisons, which may be attributable to small numbers of events within some
comparisons. Moreover, comparisons were based on single studies.
Based on a single study, significant differences were found in prevalence of childhood
obesity for CC GDM versus patients without GDM (lower prevalence for no GDM) and CC
GDM versus false positives (lower prevalence for false positives). This was consistent for both
childhood obesity >85th percentile as well as >95th percentile. However, this study was unable to
control for maternal weight or BMI, which are established predictors of childhood obesity. No
differences, based on the same single study, were found for the other four comparisons within
>85th or >95th percentiles. No other studies provided data on long-term outcomes, including type
2 diabetes mellitus and transgenerational GDM.
In summary, different thresholds of glucose intolerance affect maternal and neonatal
outcomes of varying clinical importance. While many studies have attempted to measure the
association between various criteria for GDM and pregnancy outcomes in the absence of
treatment, the ability of a study or pooled analysis to find a statistically significant difference in
pregnancy outcomes appears more dependent on study design, in particular the size of the study
or pooled analysis, rather than the criteria used for diagnosing GDM. This is not surprising given
the strong support found for a continuous positive relationship between glucose and a variety of
ES-16
pregnancy outcomes. The clinical significance of absolute differences in event rates requires
consideration by decisionmakers even though statistical significance was reached at the strictest
diagnostic glucose thresholds for some outcomes.
This question focused on outcomes for women who did not receive treatment for GDM.
While women with untreated GDM have a variety of poorer outcomes than women without
GDM, it cannot be assumed that treatment of GDM reverses all the short- and long-term poor
outcomes observed in women with untreated GDM. Some of the reasons for the poorer outcomes
in women that have untreated GDM may not be modifiable, such as the influences of genetic
makeup. The strength of evidence was insufficient for most outcomes and comparisons in this
question due to high risk of bias (observational studies), inconsistency across studies, and/or
imprecise results. The strength of evidence was low for the following outcomes and
comparisons: preeclampsia (CC GDM vs. no GDM, CC GDM vs. false positives), macrosomia
>4,000 g (CC GDM vs. no GDM, CC GDM vs. false positives, CC GDM vs. 1 abnormal OGTT,
CC false positives vs. no GDM, NDDG false positives vs. no GDM), macrosomia >4,500 g (CC
GDM vs. no GDM), and shoulder dystocia (CC GDM vs. no GDM).
Key Question 4
Eleven studies provided data for Key Question 4 to assess the effects of treatment for GDM
on health outcomes of mothers and offspring. All studies compared diet modification, glucose
monitoring, and insulin as needed with standard care. The strength of evidence for key outcomes
is summarized in Table C, and a summary of the results is provided in Table D.
Among the 11 included studies, 5 were RCTs and 6 were cohort studies. The risk of bias for
the RCTs was low for one trial, unclear for three trials, and high for one trial. The trials that were
unclear most commonly did not report detailed methods for sequence generation and allocation
concealment. The trial assessed as high risk of bias was due to lack of blinding for outcome
assessment and incomplete outcome data. The six cohort studies were all considered high
quality, with overall scores of 7 to 9 on a 9-point scale.
There was moderate evidence showing a significant difference for preeclampsia, with fewer
cases in the treated group. There was inconsistency across studies in terms of differences in
maternal weight gain, and the strength of evidence was considered insufficient. There were no
data on long-term outcomes among women, including type 2 diabetes mellitus, obesity, and
hypertension.
In terms of infant outcomes, there was insufficient evidence for birth trauma. This was driven
by lack of precision in the effect estimates and inconsistency across studies: there was no
difference for RCTs, but a significant difference favoring treatment in the one cohort study. The
incidence of shoulder dystocia was significantly lower in the treated groups, and this finding was
consistent for the three RCTs and four cohort studies. Overall, the evidence for shoulder dystocia
was considered moderate, showing a difference in favor of the treated group. For neonatal
hypoglycemia, the strength of evidence was low, suggesting no difference between groups.
Moderate evidence showed benefits of treatment in terms of macrosomia (>4,000 g).
Only one study provided data on long-term metabolic outcomes among the offspring at a 7to 11-year followup. The strength of evidence was insufficient. For both outcomes―impaired
glucose tolerance and type 2 diabetes mellitus―no differences were found between groups
although the estimates were imprecise. No differences were observed in single studies that
assessed BMI >95 (7- to 11-year followup) and BMI >85 percentile (5- to 7-year followup).
Overall, pooled results showed no difference in BMI, and the strength of evidence was low.
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In summary, there was moderate evidence showing differences in preeclampsia and shoulder
dystocia, with fewer cases among women (and offspring) who were treated compared with those
not receiving treatment. There was also moderate evidence showing significantly fewer cases of
macrosomia (>4,000 g) among offspring of women who received treatment for GDM. The
results were driven by the two largest RCTs, the Maternal Fetal Medicine Unit (MFMU)25 and
the Australian Carbohydrate Intolerance in Pregnancy Study (ACHOIS),52 which had unclear and
low risk of bias, respectively. There was little evidence showing differences between groups in
other key maternal and infant outcomes. One potential explanation is that for the most part, the
study populations included women whose glucose intolerance was less marked, as those whose
glucose intolerance was more pronounced would not have been entered into a trial in which they
may be assigned to a group receiving no treatment. For outcomes where results were inconsistent
between studies, different study glucose threshold entry criteria did not explain the variation. For
some outcomes, particularly the long-term outcomes, the strength of evidence was insufficient or
low, suggesting that further research may change the results and increase our confidence in them.
Moreover, for some outcomes events were rare, and the studies may not have had the power to
detect clinically important differences between groups; therefore, findings of no significant
difference should not be interpreted as equivalence between groups.
Table C. Strength of evidence for Key Question 4: maternal and infant outcomes
Outcome
Preeclampsia
Maternal weight gain
Birth injury
Shoulder dystocia
Neonatal hypoglycemia
Macrosomia (>4,000 g)
# Studies
(# Patients)
3 RCTs
(2,014)
1 cohort
(258)
4 RCTs
(2,530)
2 cohorts
(515)
2 RCTs
(1,230)
1 cohort
(389)
3 RCTs
(2,044)
4 cohorts
(3,054)
4 RCTs
(2,367)
2 cohorts
(2,054)
5 RCTs
(2,643)
6 cohorts
(3,426)
Overall Strength
of Evidence
moderate
(favors
treatment)
insufficient
insufficient
Comment
The evidence provides moderate confidence that
the estimate reflects the true effect in favor of the
treatment group.
There is insufficient evidence to draw conclusions
for this outcome due to inconsistency across
studies and imprecise effect estimates.
insufficient
low (no
difference)
There is insufficient evidence to make a conclusion
for this outcome. There is a difference in findings
for the RCTs and cohort studies; the number of
events and participants across all studies does not
allow for a conclusion.
insufficient
moderate (favors
treatment)
low (favors
treatment)
low (no
difference)
insufficient
moderate (favors
treatment)
low (favors
treatment)
The evidence provides moderate confidence that
the estimate reflects the true effect in favor of the
treatment group.
The evidence provides low confidence that there is
no difference between groups.
The evidence provides moderate confidence that
the estimate reflects the true effect in favor of the
treatment group.
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Table C. Strength of evidence for Key Question 4: maternal and infant outcomes (continued)
Outcome
# Studies
(# Patients)
Overall Strength
of Evidence
Long-term metabolic
outcomes: impaired
1 RCT (89)
insufficient
glucose tolerance
Long-term metabolic
1 RCT (89)
insufficient
outcomes: type 2
diabetes mellitus
Long-term metabolic
low (no
outcomes: BMI
2 RCTs
th
difference)
(assessed as >85 and (284)
th
>95 percentile)
BMI = body mass index; RCT = randomized controlled trial
Comment
There is insufficient evidence to draw conclusions
for this outcome.
There is insufficient evidence to draw conclusions
for this outcome.
The evidence provides low confidence that there is
no difference between groups.
Key Question 5
Five studies (four RCTs and one cohort study) provided data for Key Question 5 on the
harms associated with treatment of GDM. Among the four RCTs, one had low and three had
unclear risk of bias. The cohort study was high quality (7/9 points); the primary limitation was
not controlling for potential confounders.
Four of the studies provided data on the incidence of infants that were small for gestational
age and showed no significant difference between groups. This finding may have resulted from
inadequate power to detect differences due to a small number of events; therefore, the finding of
no significant difference should not be interpreted as equivalence between groups.
Four of the studies provided data on admission to the NICU and showed no significant
differences overall. One study was an outlier because it showed a significant difference favoring
the no treatment group. This difference may be attributable to site-specific policies and
procedures or lack of blinding of investigators to treatment arms. Two studies reported on the
number of prenatal visits and generally found significantly more visits between the treatment
groups.
Two of the RCTs showed no significant difference overall in the rate of induction of labor,
although there was important statistical heterogeneity between studies. One RCT showed
significantly more inductions of labor in the treatment group,52 while the other study did not.25
Different study protocols may account for the heterogeneity of results between studies. In the
first study that showed more inductions of labor in the treatment group, no recommendations
were provided regarding obstetrical care. In the second study, antenatal surveillance was
reserved for standard obstetrical indications. Based on the studies included in Key Question 4
(five RCTs and six cohort studies), there was no difference in rates of cesarean section between
treatment and nontreatment groups.
A single study assessed depression and anxiety at 6 weeks after study entry and 3 months
postpartum using the Spielberger State-Trait Anxiety Inventory and the Edinburgh Postnatal
Depression Score, respectively. There was no significant difference in anxiety between the
groups at either time point, although there were significantly lower rates of depression in the
treatment group at 3 months postpartum. These results should be interpreted cautiously because
the assessment of depression and anxiety was conducted in a subgroup of the study population.
There was no evidence for some of the outcomes stipulated in the protocol, including costs
and resource allocation.
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Findings in Relationship to What Is Already Known
This review provides evidence that treating GDM reduces some poor maternal and neonatal
outcomes. The recent MFMU trial25 published in 2009 reinforces the findings of the earlier
ACHOIS trial that was published in 200552 and included in an earlier version of this review.24
Both trials showed that treating GDM to targets of 5.3 or 5.5 mmol/L fasting and 6.7 or 7.0
mmol/L 2 hours postmeal reduced neonatal birthweight, large for gestational age, macrosomia,
shoulder dystocia, and preeclampsia, without a reduction in neonatal hypoglycemia or
hyperbilirubinemia/jaundice requiring phototherapy, or an increase in small for gestational age.
In contrast to the ACHOIS trial, MFMU demonstrated a reduced cesarean section rate in the
GDM treatment group. The failure of ACHOIS to find a lower cesarean section rate despite
reduced neonatal birthweight and macrosomia may have been the result of differing obstetrical
practices or the different populations studied (e.g., the inclusion of some women with more
marked glucose intolerance in ACHOIS, as reflected by the increased prevalence of insulin use;
more black and Hispanic women in the MFMU study). Differences may have also resulted due to
study design: in the ACHOIS trial, participants did not receive specific recommendations
regarding obstetrical care, thus treatment was left to the discretion of the delivering health care
provider. In the MFMU study, antenatal surveillance was reserved for standard obstetrical
indications. Our findings of the effect of treatment of GDM is similar to a systematic review and
meta-analysis published in 2010 by Horvath and colleagues.53 This review included two older
RCTs of GDM that were not included in our analysis because we restricted our inclusion criteria
to studies published after 1995.
The HAPO Study Cooperative Research Group3 used a simpler 75 g OGTT in a large
international sample of women and confirmed findings of the earlier Toronto Trihospital study51
that there is a continuous positive association between maternal glucose and increased
birthweight, as well as fetal hyperinsulinemia (HAPO only), at levels below diagnostic
thresholds for GDM that existed at the time of the study. However, no clear glucose thresholds
were found for fetal overgrowth or a variety of other maternal and neonatal outcomes.
Subsequently, the IADPSG developed diagnostic thresholds for GDM based on a consensus of
expert opinion of what was considered to be the most important outcomes and the degree of
acceptable risk for these outcomes. The thresholds chosen by the IADPSG were derived from the
HAPO data to identify women with a higher risk (adjusted odds ratio 1.75) of large for
gestational age, elevated c-peptide, and high neonatal body fat compared with the mean maternal
glucose values of the HAPO study. The glucose threshold chosen by the IADPSG represents
differing levels of risk for other outcomes. Specifically, their thresholds represent a 1.4 (1.26–
1.56) risk for pregnancy-induced hypertension and a 1.3 (1.07–1.58) risk for shoulder dystocia.
A dichotomous view of GDM may no longer be appropriate, given evidence of a continuous
relationship between maternal blood glucose and pregnancy outcomes. An alternative approach
may be to define different glucose thresholds based on maternal risk for poor pregnancy
outcomes. This approach has been used in the context of lipid levels and risk of adverse
cardiovascular outcomes.
Neither recent RCT was designed to determine diagnostic thresholds for GDM or therapeutic
glucose targets. However, it is noteworthy that therapeutic glucose targets for both ACHOIS and
MFMU were above the proposed diagnostic criteria of the IADPSG (fasting 5.5 mmol/L [99
mg/dL] and 5.3 mmol/L [95 mg/dL] and 2 hour postmeal of 7.0 mmol/L [126 mg/dL and 6.7
mmol/L 120 mg/dL], respectively). A change in diagnostic criteria without addressing
management thresholds could contribute to clinical confusion. If diagnostic thresholds for GDM
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below the treatment targets of the large RCTs are endorsed, this could ethically obstruct the
possibility of future RCTs to compare different treatment targets above such diagnostic
thresholds.
It has been hypothesized that treatment of GDM may reduce future poor metabolic outcomes
for children born to mothers with GDM. If true, the potential for long-term gain is important
from a clinical and public health perspective and may justify the “costs” of screening and
treating women for GDM. However, the followup of offspring from two RCTs52,54 and a HAPO
cohort in Belfast 55 currently fail to support this hypothesis. This may be explained in part due to
insufficient length of followup or inadequate numbers of events.
The HAPO study showed that maternal weight and glucose predict large for gestational age.
However, BMI was the better predictor of large for gestational age than glucose until glucose
thresholds higher than the diagnostic thresholds set by the IADPSG were reached.56,57 Most cases
of large for gestational age occur in neonates of mothers with normal glycemia. A large
observational study found that the upper quartile of maternal BMI accounted for 23 percent of
macrosomia, while GDM was responsible for only 3.8 percent.58
The ongoing obesity epidemic in the United States warrants careful consideration of a
diagnostic approach for GDM that incorporates maternal BMI. This would require the
development and validation of a risk model that incorporates maternal BMI as well as other
modifiable risk factors. Such a model could facilitate the identification of women at high risk of
adverse pregnancy outcomes and minimize exposure of lower risk women to unnecessary
interventions.
Applicability
Several issues may limit the applicability of the evidence presented in this review to the U.S.
population. All of the Key Questions asked about the effects of screening and treatment before
and after 24 weeks’ gestation. The vast majority of included studies screened women after 24
weeks’ gestation; therefore, the results are not applicable to screening and treatment earlier in
gestation.
For Key Question 1 on the test properties of screening and diagnostic tests, comparisons
involving the WHO criteria are less applicable to the U.S. setting because these criteria are not
used in North America. There were insufficient data from the included studies to assess the
performance of screening or diagnostic tests for specific patient characteristics (e.g., BMI,
race/ethnicity). Therefore it is unclear whether the evidence applies to specific subpopulations of
women.
For Key Question 2, limited evidence was identified because the comparison of interest was
women who had not undergone screening. Because screening is routine in prenatal care in the
United States, the evidence (or limited evidence) is likely not helpful for U.S. decisionmaking,
and a refinement of this question may be appropriate to reflect current practices and outstanding
questions.
With respect to Key Question 3, all studies or groups included for analysis involved women
who had not received treatment for GDM. It cannot be assumed that the same associations and
outcomes would be observed in clinical practice in which standard care is to screen for and treat
GDM. The untreated women may differ from the general population in ways that are related to
the reasons for which they did not seek or receive early prenatal care (e.g., socioeconomic
status). That is, the reasons they did not receive treatment for GDM are varied; some reasons,
such as late presentation for obstetrical care, may confound the observed association with health
ES-21
outcomes. Attempts were made to control for these factors in some studies (e.g., Langer and
colleagues59) by including a group of women without GDM with similar known confounders or
by adjusting for known confounders in the analysis. The adjusted estimates did not change the
overall pooled results in the majority of cases and did not change the overall conclusions.
The majority of the studies for Key Questions 4 and 5 pertaining to the benefits and harms of
treatment for GDM were conducted in North America or Australia. Most of the North American
studies were inclusive of mixed racial populations and are likely applicable to the general U.S.
population. Even though the Australian RCT52 population had more white women with a lower
BMI than the U.S. RCT (MFMU25), this should not affect applicability of most of their findings
because these patient characteristics would be factors associated with lower risk of poor
outcomes. Differences in physician or hospital billing structures between the United States and
Australia may have accounted for the discrepant findings with respect to NICU admissions and,
as a result, may limit the applicability of this finding in the United States. Among the studies
included in Key Questions 4 and 5, a variety of glucose threshold criteria were used for
inclusion, varying from 50 g screen positive with nondiagnostic OGTTs, to women who met
NDDG criteria for a diagnosis of GDM. The two large RCTs25,52 used different glucose
thresholds for entry in their trials: WHO and CC criteria with a fasting glucose <95 mg/dL (5.3
mmol/L), respectively. The mean glucose levels at study entry were similar between these two
RCTs, which may reflect a reluctance to assign women with more marked glucose intolerance to
a group receiving no treatment. The results may not be applicable to women with higher levels of
glucose intolerance.
Limitations of the Evidence Base
There is sparse evidence to clarify issues regarding the timing of screening and treatment for
GDM (i.e., before and after 24 weeks’ gestation). Earlier screening will help identify overt type 2
diabetes mellitus and distinguish this from GDM. This has important implications for clinical
management and ongoing followup beyond pregnancy. Previously unrecognized type 2 diabetes
mellitus diagnosed in pregnancy should be excluded from the diagnosis of GDM because this
condition has the highest perinatal mortality rate of all classes of glucose intolerance in
pregnancy.60 This distinction within research studies will provide more targeted evidence to help
obstetrical care providers to risk stratify obstetrical care and glycemic management of patients
with overt type 2 diabetes mellitus diagnosed in pregnancy and those with less pronounced
pregnancy-induced glucose intolerance. This will also facilitate better comparability across
future studies. Few data were available on long-term outcomes. Furthermore, the studies
included in this review do not provide evidence of a direct link between short-term and longterm outcomes (e.g., macrosomia and childhood obesity).
Care provider knowledge of the glucose screening and diagnostic results may have
introduced a bias if their subsequent treatment of women differed depending on the results. This
was of particular concern for Key Question 3, which assessed how the various criteria for GDM
influenced pregnancy outcomes. For Key Question 3, many of the statistically significant
differences seemed to be driven by the size of the study or pooled analysis (i.e., statistically
significant differences could be found if the sample were sufficiently large). However, these
differences may not be clinically important. The absolute differences in event rates between
different glucose thresholds need careful consideration by decisionmakers, even though
statistically significant differences were found. Another key limitation with the evidence for Key
Question 3 is that the studies included were cohort studies, many of which did not control for
ES-22
potential confounders. Therefore, any associations between glucose thresholds and outcomes
should be interpreted with caution.
Given that the large landmark studies51,61 show a continuous relationship between glucose
and maternal and neonatal outcomes, the lack of clear thresholds contributes to the uncertainty
regarding a diagnostic threshold for GDM. While there is controversy about where to set lower
limits for diagnostic criteria, the identification of overt diabetes in pregnancy is imperative if this
diagnosis has not occurred before pregnancy. Overt diabetes first identified in pregnancy should
be distinguished from GDM to gain a better understanding of the true risk of GDM to pregnancy
outcomes. Unfortunately there is no literature to guide diagnostic criteria for a diagnosis of overt
diabetes in pregnancy.
There were several methodological concerns for this evidence base. For example, risk of
spectrum bias and partial verification bias (Key Question 1); different definitions or methods of
assessing key outcomes (e.g., clinical vs. biochemical neonatal hypoglycemia and
hyperbilirubinemia) (Key Questions 3 and 4); and lack of blinding of treatment arms in some
studies (Key Questions 4 and 5).
Future Research
Several important gaps in the current literature exist:
• The adoption of a consistent comparator for diagnosis of GDM, such as the 75 g OGTT,
would facilitate comparisons across studies even if different diagnostic thresholds are
used.
• Further analysis of the HAPO data could help answer some outstanding questions. For
example, further analysis could better define absolute differences in rare event rates. This
evidence could be used to inform discussions about the clinical importance of absolute
differences in event rates at thresholds other than those of the IADPSG. Such analyses
should include adjustment for important confounders such as maternal BMI.
• Further analysis of the HAPO data, examining center-to-center differences in glucose
outcome relationships would be helpful in determining the usefulness of FPG as a
screening test for GDM.
• Research is needed to clarify issues regarding earlier screening and treatment, particularly
as they relate to the diagnosis, treatment, and long-term outcomes of pregestational
(overt) diabetes.
• Further research of FPG, a screening test, is needed, given that the reproducibility of
fasting glucose measurement is superior to postglucose load measurements.62
• Further study of the long-term metabolic outcomes in offspring whose mothers have been
treated for GDM is warranted. In addition, data on the influences of GDM treatment on
long-term breastfeeding success have not been studied. The association of breastfeeding
with reduced poor metabolic outcomes in offspring of GDM has been found to have a
dose-dependent response with duration of breastfeeding.63
• Implementation of well-conducted prospective cohort studies of the “real world” effects
of GDM treatment on use of care is needed.
• Research on outcomes is needed to help determine the glucose thresholds and treatment
targets at which GDM treatment benefits outweigh the risks of treatment and no
treatment. This will best be achieved through well-conducted, large RCTs that randomize
women with GDM to different glucose treatment targets.
ES-23
•
•
•
•
•
•
While this review did not identify evidence of substantial harms to treatment, the
populations considered were mostly women whose GDM was controlled without
medication. There is a risk for more precautionary management of women diagnosed
with GDM, who are perceived by clinicians to be at greater risk, such as those managed
with insulin, which may result in unnecessary interventions (e.g., cesarean section).64
Therefore, RCTs investigating the care of women diagnosed with GDM, including fetal
surveillance protocols, are needed to guide obstetrical investigations and management of
GDM. Further, RCTs comparing delivery management for GDM with and without
insulin or medical management are needed to provide clinicians guidance on appropriate
timing and management of delivery in women with GDM to avoid unnecessary
intervention in “the real world” driven by health care provider apprehension.
The development of long-term studies that evaluate the potential increased or decreased
resource use associated with the implementation of diabetes prevention strategies after a
diagnosis of GDM is required.
Studies to assess the long-term results that a label of GDM may have for future
pregnancy planning, future pregnancy management, and future insurability are required.
The increased prevalence of type 2 diabetes mellitus in women of reproductive age merits
consideration of preconception screening for overt diabetes in women at risk of type 2
diabetes. In addition to poor maternal and neonatal outcomes associated with overt
diabetes in pregnancy, there is potential for benefit of preconception care.
Long-term benefits and harms need to be evaluated among different treatment modalities
for GDM (e.g., diet, exercise, insulin, oral glucose-lowering medications, and/or
combinations of these).
Since 2011–2012, the American Diabetes Association has endorsed the use of an HbA1c
of 6.5 percent or more as a diagnostic of diabetes in nonpregnant women.36 Studies of
HbA1c with trimester-specific cutoffs to determine the value at which overt diabetes
should be diagnosed in pregnancy are needed.
Limitations of the Review
This review followed rigorous methodological standards, which were detailed a priori. The
limitations of the review to fully answer the Key Questions are largely due to the nature and
limitations of the existing evidence.
Several limitations need to be discussed regarding systematic reviews in general. First, there
is a possibility of publication bias. The effects of publication bias on the results of diagnostic test
accuracy reviews (Key Question 1) is not well understood, and the tools to investigate
publication bias in these reviews have not been developed. For the remaining Key Questions, we
may be missing unpublished and/or negative therapy studies and may be overestimating the
benefits of certain approaches. However, we conducted a comprehensive and systematic search
of the published literature for potentially relevant studies. Search strategies included
combinations of subject headings and free text words. These searches were supplemented by
handsearching for gray literature (i.e., unpublished or difficult-to-find studies). Despite these
efforts, we recognize that we may have missed some studies.
There is also a possibility of study selection bias. However, we employed at least two
independent reviewers and feel confident that the studies excluded from this report were done so
for consistent and appropriate reasons. Our search was comprehensive, so it is unlikely that many
studies in press or publication were missed.
ES-24
Cost analysis of different screening and diagnostic approaches was not addressed in this
review.
Conclusions
There was limited evidence regarding the test characteristics of current screening and
diagnostic strategies for GDM. Lack of an agreed-upon gold standard for diagnosing GDM
creates challenges for assessing the accuracy of tests and comparing across studies. The 50 g
OGCT with a glucose threshold of 130 mg/dL versus 140 mg/dL improves sensitivity and
reduces specificity (10 studies). Both thresholds have high negative predictive value, but variable
positive predictive value across a range of GDM prevalence. There was limited evidence for the
screening of GDM diagnosed less than 24 weeks’ gestation (3 studies). Single studies compared
the diagnostic characteristics of different pairs of diagnostic criteria in the same population. The
use of fasting glucose (≥85 mg/dL) as a screen for GDM may be a practical alternative because
of similar test characteristics to the OGCT, particularly in women who cannot tolerate any form
of oral glucose load.
Evidence supports benefits of treating GDM, with little evidence of short-term harm.
Specifically, treatment of GDM results in lower incidence of preeclampsia, macrosomia, and
large for gestational age infants. Current research does not demonstrate a treatment effect of
GDM on clinical neonatal hypoglycemia or future poor metabolic outcomes of the offspring.
RCTs of GDM treatment show limited harm related to treating GDM, other than an increased
demand for services. There is a risk for more precautionary management of women diagnosed
with GDM, who are perceived by clinicians to be at greater risk, such as those managed with
insulin, which may result in unnecessary interventions (e.g., cesarean section); however, this
review found limited data for these outcomes, and further research on the care of women
diagnosed with GDM (e.g., fetal surveillance protocols) is warranted.
What remains less clear is what the lower limit diagnostic thresholds for GDM should be.
Given the continuous association between glucose and a variety of outcomes, decisions should
be made in light of what outcomes altered by treatment are the most important and what level of
increased risk is acceptable. A dichotomous view of GDM may no longer be appropriate, given
evidence of a continuous relationship between maternal blood glucose and pregnancy outcomes.
An alternative approach would be to define different glucose thresholds based on maternal risk
for poor pregnancy outcomes.
Further study is needed regarding the long-term metabolic outcomes on offspring of mothers
receiving GDM treatment; the “real world” impact of GDM treatment on use of care outside of
structured research trials; and the results of the timing of screening for GDM, particularly before
24 weeks’ gestation and in the first trimester of pregnancy. Early screening could help identify
pregestational (i.e., overt) diabetes. Research is urgently required to determine the best way to
diagnose and manage overt diabetes in pregnancy, particularly in an era of increasing rates of
obesity and diabetes in the U.S. population.
ES-25
Table D. Summary of evidence for all Key Questions
Key Question
Number and Quality
of Studies
Limitations/
Consistency
Applicability
•
•
KQ1. What are the
sensitivities,
specificities,
reliabilities, and
yields of current
screening tests for
GDM? (a) After 24
weeks’ gestation?
(b) During the first
trimester and up to
24 weeks’
gestation?
Limitations: Lack of an
agreed upon gold standard
for diagnosis of GDM creates
challenges for assessing the
accuracy of tests and
comparing across studies.
GDM was confirmed using
criteria developed by CC,
ADA, NDDG, and WHO.
(a) After 24 wk
gestation
51 prospective studies
Fair to good quality
There were sparse data
comparing overall
approaches for diagnosis
and screening, e.g., one-step
vs. two-step, selective vs.
universal.
Consistency: Across studies
numerous tests and
thresholds were examined.
Screening tests included the
50 g OGCT, FPG, risk factorbased screening, and other
less common tests such as
HbA1c, serum fructosamine.
•
Prevalence of GDM
varied across studies and
diagnostic criteria used.
Results need to be
interpreted in the context
of prevalence.
Comparisons involving
WHO criteria are less
applicable to the North
American setting
because these criteria
are not used in North
America.
ES-26
•
•
•
•
Summary of Findings
Prevalence varied across studies and diagnostic
criteria: ADA 2000-2010 (75 g) 2.0 to 19%
(range), CC 3.6 to 38%, NDDG 1.4 to 50%,
WHO 2 to 24.5%.
9 studies examined a 50 g OGCT with a cutoff
value of ≥140 mg/dL; GDM was confirmed using
CC criteria. Results: sensitivity 85%, specificity
86%, prevalence 3.8 to 31.9%, PPV 18 to 27%
(prevalence <10), PPV 32 to 83% (prevalence
≥10), NPV median 98%.
6 studies examined a 50 g OGCT (≥130 mg/dL);
GDM was confirmed using CC criteria. Results:
sensitivity 99%, specificity 77%, prevalence 4.3
to 29.5%, PPV 11 to 31% (prevalence <10),
PPV 31 to 62% (prevalence ≥10), NPV median
100%.
1 study examined a 50 g OGCT (≥200 mg/dL);
GDM was confirmed using CC criteria.
Sensitivity, specificity, PPV, and NPV were all
100%. Prevalence was 6.4%.
7 studies examined a 50 g OGCT (≥140 mg/dL);
GDM was confirmed using NDDG criteria.
Results: sensitivity 85%, specificity 83%,
prevalence 1.4 to 45.8%, PPV 12 to 39%
(prevalence <10), PPV 57% (prevalence ≥10),
NPV median 99%.
3 studies examined a 50 g OGCT (≥130 mg/dL);
GDM was confirmed using NDDG criteria.
Results: sensitivity 67 to 90% (range), specificity
47 to 84%; prevalence 16.7 to 35.3%, PPV 20 to
75%, NPV 86 to 95%.
3 studies examined a 50 g OGCT (different
thresholds); GDM was confirmed using ADA
2000-2010 (75 g) criteria. Prevalence was 1.6 to
4.1% (range). Results: sensitivity 86 to 97%
(range), specificity 79 to 87%; PPV 7 to 20%,
NPV 99 to 100%.
Table D. Summary of evidence for all Key Questions (continued)
Key Question
Number and Quality
of Studies
Limitations/
Consistency
Applicability
•
•
KQ1. What are the
sensitivities,
specificities,
reliabilities, and
yields of current
screening tests for
GDM? (a) After 24
weeks’ gestation?
(b) During the first
trimester and up to
24 weeks’
gestation?
(a) After 24 wk
gestation
51 prospective studies
Fair to good quality
•
(a) After 24 wk gestation
51 prospective studies
Fair to good quality
(continued)
•
(continued)
•
ES-27
Summary of Findings
3 studies examined a 50 g OGCT (≥140 mg/dL);
GDM was confirmed using WHO criteria.
Results: sensitivity 43 to 85%, specificity 73 to
94%, prevalence 3.7 to 15.7%, PPV 18 to 20%
(prevalence <10), PPV 58% (prevalence ≥10),
NPV median 99%.
7 studies examined FPG at different thresholds;
GDM was confirmed using CC criteria. Results:
at ≥85 mg/dL sensitivity 87%, specificity 52%; at
≥90 mg/dL sensitivity 77%, specificity 76%; at
≥92 mg/dL sensitivity 76%, specificity 92%; at
≥95 mg/dL sensitivity 54%, specificity 93%. At
≥85 mg/dL prevalence 1.4 to 34.53 (range).
PPV 10% (prevalence <10) and 23 to 59%
(prevalence ≥10). Median NPV 93%.
8 studies examined risk factor-based screening
but were not pooled. Studies used different
criteria to confirm GDM. Results: sensitivity 48
to 95% (range), specificity 22 to 94%,
prevalence 1.7 to 16.9%, PPV 5 to 19%
(prevalence <10), PPV 20% (prevalence ≥10),
NPV median 99%.
1 study compared IADPSG vs. ADIPS 2 step
(reference) to diagnose GDM. Results:
sensitivity 82%, specificity 94%, prevalence
13.0%, PPV 61%, NPV 98%.
4 studies compared 75 g and 100 g load tests to
diagnose GDM. Prevalence ranged from 1.4 to
50%. Results were not pooled: sensitivity 18 to
100%, specificity 86 to 100%, PPV 12 to 100%,
NPV 62 to 100%.
Table D. Summary of evidence for all Key Questions (continued)
Key Question
KQ1. What are the
sensitivities,
specificities,
reliabilities, and
yields of current
screening tests for
GDM? (a) After 24
weeks’ gestation?
(b) During the first
trimester and up to
24 weeks’
gestation?
Number and Quality
of Studies
(b) During the first
trimester and up to
24 wk gestation
3 prospective cohort
studies
Limitations/
Consistency
Applicability
Limitations: Only 3 studies of
women before 24 wks
gestation; therefore, no
conclusions can be made for
test characteristics in early
pregnancy.
•
Evidence too limited to
judge applicability.
Consistency: Not applicable
(not enough studies
addressing the same
question to judge
consistency).
(continued)
KQ2: What is the
direct evidence on
the benefits and
harms of
screening women
(before and after
24 weeks’
gestation) for GDM
to reduce
maternal, fetal, and
infant morbidity
and mortality?
Limitations: No RCTs
available to answer this
question.
2 retrospective cohort
studies
Fair and good quality
Consistency: Not applicable
(not enough studies
addressing the same
question to judge
consistency).
•
The comparison for this
question was women
who had and had not
undergone screening.
Since screening is now
commonplace, it may be
unlikely to identify studies
or cohorts where this
comparison is feasible.
ES-28
•
Summary of Findings
1 study examined the 50 g OGCT at 10 wks and
confirmed GDM using JSOG criteria (75 g).
Results: sensitivity 88%, specificity 79%,
prevalence 1.6%, PPV 7%, NPV 100%.
1 study examined 50 g OGCT at 20 wks and
confirmed GDM using ADA (2000-2010) 100 g
criteria. Results: sensitivity 56%, specificity
94%, prevalence 3.6%, PPV 24%, NPV 98%.
st
nd
1 study compared 1 and 2 trimester results
using 3 screening tests (OGCT at ≥130 mg/dL,
FPG, HbA1c); GDM confirmed using JSOG
st
criteria. Results (OGCT) 1 trimester:
prevalence 1.9%, sensitivity 93%, specificity
nd
77%, PPV 7.1, NPV 99%; 2 trimester:
prevalence 2.9%, sensitivity 100%, specificity
85%, PPV 17%, NPV 100%.
1 study (n=1,000) showed more cesarean deliveries
in the screened group. A second study (n=93) found
the incidence of macrosomia (≥4.3 kg) was the
same in screened and unscreened groups (7% each
group).
Based on the small number of studies and sample
sizes, the effect of screening women for GDM on
health outcomes is inconclusive.
Table D. Summary of evidence for all Key Questions (continued)
Key Question
KQ3: In the
absence of
treatment, how do
health outcomes
of mothers who
meet various
criteria for GDM
and their offspring
compare to those
who do not meet
the various
criteria?
Number and Quality
of Studies
38 prospective or
retrospective cohort
studies; 2 studies
were long-term
followup from RCTs;
however, only data
from the untreated
patients were
included.
Fair to good quality
Limitations/
Consistency
Applicability
Limitations: Strength of
evidence was low to
insufficient for all graded
outcomes due to risk of bias
(all observational studies),
inconsistency, and/or
imprecision. For many
comparisons, the numbers of
studies, participants, and/or
events was low; therefore,
findings of no statistically
significant differences
between groups do not imply
equivalence or rule out
potential differences.
Consistency: A wide variety
of diagnostic criteria and
thresholds were compared
across studies. There were
often few studies with similar
comparison groups.
Differences in defining and
assessing outcomes may
have contributed to
heterogeneity in results
across studies (e.g.,
biochemical vs. clinical
assessment of neonatal
hypoglycemia).
All studies or groups
included for analysis
involved women who had
not received treatment for
GDM. These women may
differ from the general
population in other ways
that are related to the
reasons why they did not
seek or receive early
prenatal care (e.g.,
socioeconomic status).
ES-29
Summary of Findings
Maternal outcomes:
•
A methodologically strong study showed a
continuous positive relationship between
increasing glucose levels and the incidence of
primary cesarean section. This study also found
significantly fewer cases of preeclampsia and
cesarean section for women with no GDM vs.
IADPSG.
•
For preeclampsia, significant differences were
found for CC vs. patients with no GDM (3
studies), with fewer cases among the patients
with no GDM, and for CC vs. false-positive
groups (2 studies), with fewer cases among the
false positives. The strength of evidence was
low. No differences were found for NDDG false
positive (2 studies), NDDG 1 abnormal OGTT
vs. no GDM (1 study), or IGT WHO vs. no GDM
(3 studies); the strength of evidence was
insufficient.
•
For maternal weight gain, significant differences
were found for 3 of 12 comparisons: IADPSG
IGT vs. no GDM (favored IGT), IADPSG IFG vs.
no GDM (favored IFG), IADPSG IGT-2 vs. no
GDM (favored IGT-2). All comparisons were
based on single studies (strength of evidence
insufficient).
Fetal/neonatal/child outcomes:
•
2 methodologically strong studies showed a
continuous positive relationship between
increasing glucose levels and the incidence of
macrosomia. 1 of these studies also showed
significantly fewer cases of shoulder dystocia
and/or birth injury, clinical neonatal
hypoglycemia, and hyperbilirubinemia for
women with no GDM vs. IADPSG.
Table D. Summary of evidence for all Key Questions (continued)
Key Question
KQ3: In the
absence of
treatment, how do
health outcomes
of mothers who
meet various
criteria for GDM
and their offspring
compare to those
who do not meet
the various
criteria?
Number and Quality
of Studies
Limitations/
Consistency
Applicability
38 prospective or
retrospective cohort
studies; 2 studies
were long-term
followup from RCTs;
however, only data
from the untreated
patients were
included.
Fair to good quality
•
•
(continued)
(continued)
ES-30
Summary of Findings
For macrosomia >4,000 g, 6 of 11 comparisons
showed a significant difference: patient groups
with no GDM had fewer cases compared with
CC GDM (10 studies), CC 1 abnormal OGTT (7
studies), NDDG GDM (unrecognized) (1 study),
NDDG false positives (4 studies), and WHO IGT
(1 study). Fewer cases were found for women
with false-positive results compared with CC
GDM (5 studies). Data for macrosomia >4,500 g
were available for 4 comparisons and showed
significant differences in 2 cases: patient groups
with no GDM had fewer cases compared with
CC GDM (3 studies) and unrecognized NDDG
GDM (1 study). The strength of evidence for
macrosomia was low to insufficient.
For shoulder dystocia, significant differences
were found for 7 of 17 comparisons; all
comparisons but 1 were based on single studies
(insufficient strength of evidence). Patient
groups with no GDM showed lower incidence of
shoulder dystocia when compared with CC
GDM (5 studies, low strength of evidence),
NDDG GDM (unrecognized), NDDG false
positive, WHO IGT, IADPSG IFG, and IADPSG
IGT IFG. The other significant difference
showed lower incidence among the falsepositive group compared with CC 1 abnormal
OGTT.
Table D. Summary of evidence for all Key Questions (continued)
Key Question
KQ3: In the
absence of
treatment, how do
health outcomes
of mothers who
meet various
criteria for GDM
and their offspring
compare to those
who do not meet
the various
criteria?
Number and Quality
of Studies
Limitations/
Consistency
Applicability
38 prospective or
retrospective cohort
studies; 2 studies
were long-term
followup from RCTs;
however, only data
from the untreated
patients were
included.
Fair to good quality
(continued)
(continued)
KQ4: Does
treatment modify
the health
outcomes of
mothers who meet
various criteria for
GDM and
offspring?
5 RCTs and 6
retrospective cohort
studies.
Poor to good quality
Limitations: For some
outcomes, particularly the
long-term outcomes, the
strength of evidence was
insufficient or low. Moreover,
for some outcomes events
were rare, and the studies
may not have had the power
to detect clinically important
differences between groups;
therefore, findings of no
significant difference should
not be interpreted as
equivalence between groups.
For the most part, study
populations included
women whose glucose
intolerance was less
marked, as those whose
glucose intolerance was
more pronounced would
not be entered into a trial
in which they may be
assigned to a group
receiving no treatment.
The majority of studies
were conducted in North
America or Australia, with
2 from Italy. Most of the
North American studies
were inclusive of mixed
racial populations and
are likely applicable to
the general U.S.
population.
ES-31
•
Summary of Findings
For fetal birth trauma/injury, single studies
compared CC GDM and WHO IGT with no
GDM and showed no differences. Two studies
showed fewer cases for no GDM compared with
NDDG GDM. Strength of evidence was
insufficient for all comparisons.
•
No differences were found for neonatal
hypoglycemia for any comparison, including CC
GDM vs. no GDM (3 studies), CC GDM vs. 1
abnormal OGTT (1 study), CC 1 abnormal
OGTT vs. no GDM (4 studies), NDDG GDM vs.
no GDM (1 study), NDDG false positive vs. no
GDM (1 study), and WHO IGT vs. no GDM (3
studies). Strength of evidence was insufficient
for all comparisons.
Maternal outcomes:
•
Moderate evidence from 3 RCTs showed a
significant difference for preeclampsia, with
fewer cases in the treated group.
•
There was inconsistency across studies in
terms of maternal weight gain (4 RCTs and 2
cohort studies); the strength of evidence was
insufficient due to inconsistency and imprecision
in effect estimates.
Offspring outcomes:
•
There was insufficient evidence to make a
conclusion for birth injury. There was
inconsistency across studies, with the 2 RCTs
showing no difference and the 1 cohort study
showing a difference in favor of the treated
group. The low number of events and
participants across all studies resulted in
imprecise estimates.
•
Moderate evidence showed significantly lower
incidence of shoulder dystocia in the treated
groups, and this finding was consistent for the 3
RCTs and 4 cohort studies.
Table D. Summary of evidence for all Key Questions (continued)
Key Question
KQ4: Does
treatment modify
the health
outcomes of
mothers who meet
various criteria for
GDM and
offspring?
(continued)
Number and Quality
of Studies
5 RCTs and 6
retrospective cohort
studies.
Poor to good quality
(continued)
Limitations/
Consistency
Consistency: Some
inconsistency occurred at 2
levels. First, there were
inconsistencies for some
outcomes between RCTs
and observational studies,
which may be attributable to
confounding and methods of
selecting study groups (e.g.,
historical control groups).
Second, in some instances
there were inconsistencies
across studies within
designs, that were often
attributable to the manner in
which outcomes were
defined or assessed (e.g.,
clinical vs. biochemical
assessment of neonatal
hypoglycemia).
Applicability
Summary of Findings
•
Even though the
Australian RCT
population had more
white women with a lower
BMI than the U.S. RCTs;
this should not affect
applicability of most of
their findings for the U.S.
women because these
subject characteristics
would be factors
associated with lower risk
of poor outcomes.
ES-32
•
•
•
There was low evidence of no difference
between groups for neonatal hypoglycemia
based on 4 RCTs and 2 cohort studies.
For outcomes related to birthweight (including
macrosomia >4,000 g, macrosomia >4,500 g,
actual birthweight, and large for gestational
age), differences were often observed favoring
the treated groups. Strength of evidence was
moderate for macrosomia >4,000 g.
1 RCT followed patients for 7 to 11 years and
found no differences for impaired glucose
tolerance or type 2 DM, although the strength of
evidence was considered insufficient.
No differences were observed in single studies
that assessed BMI >95 (7-11 yr followup) and
BMI >85 percentile (5-7 yr followup). Overall,
pooled results showed no difference in BMI, and
the strength of evidence was considered low.
Table D. Summary of evidence for all Key Questions (continued)
Key Question
Number and Quality
of Studies
Limitations/
Consistency
Applicability
•
Summary of Findings
1 RCT assessed depression and anxiety at 6
weeks after study entry and 3 months
postpartum.
•
There was no significant difference between
groups in anxiety at either time point, although
there were significantly lower rates of
Limitations: No study
depression in the treatment group at 3 months
evaluated costs and resource
postpartum.
As above for KQ4. In
allocation. Limited evidence
•
4 RCTs reported small for gestational age and
addition, differences in
on harms. Limited evidence
found no significant difference.
billing structures between
for number of prenatal visits
•
3 RCTs and 1 cohort study provided data on
the United States and
and NICU admissions.
admission to NICU and showed no significant
KQ5: What are the
Australia may have
Findings of no significant
4 RCTs and 1
differences overall. One trial was an outlier
harms of treating
accounted for the
differences may be
retrospective cohort
because it showed a significant difference
GDM and do they
discrepant
findings
with
attributable to low power and
study.
favoring the no treatment group. This difference
vary by diagnostic
respect to NICU
should not be interpreted as
Fair to good quality
may be attributable to site-specific policies and
approach?
admissions between
equivalence.
procedures.
these studies and as a
•
2 RCTs reported on the number of prenatal
result limit the
visits and generally found more visits among the
Consistency: Not applicable
applicability of this finding
treatment groups.
(not enough studies
in the United States.
•
2 RCTs reporting on induction of labor showed
addressing the same
different results, with 1 showing a significant
question to judge).
difference with more cases in the treatment
group and the other showing no difference.
•
Based on studies included in KQ4, no
differences between groups were found for
cesarean section (5 RCTs, 6 cohorts) or
unplanned cesarean section (1 RCT, 1 cohort).
ADA = American Diabetes Association; ADIPS = Australasian Diabetes in Pregnancy Society; BMI = body mass index; CC = Carpenter and Coustan; DM = type 2 diabetes
mellitus; FPG = fasting plasma glucose; GDM = gestational diabetes mellitus; HbA1c = glycated hemoglobin; IADPSG = International Association of Diabetes in Pregnancy
Study Groups; IFG = impaired fasting glucose; IGT = impaired glucose tolerance; IGT-2 = double impaired glucose tolerance; JSOG = Japan Society of Obstetrics and
Gynecology; NDDG = National Diabetes Data Group; NPV = negative predictive value; NICU = neonatal intensive care unit; OGCT = oral glucose challenge test; OGTT = oral
glucose tolerance test; PPV = positive predictive value; RCT = randomized controlled trial; wk(s) = week(s); WHO = World Health Organization
ES-33
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Introduction
Gestational Diabetes Mellitus
Gestational diabetes mellitus (GDM) is defined as glucose intolerance first discovered in
pregnancy. Pregestational diabetes refers to any type of diabetes diagnosed before pregnancy.
Pregnant women with pregestational diabetes experience an increased risk of poor maternal, fetal
and neonatal outcomes.1 The extent to which GDM predicts adverse outcomes for mother, fetus
and neonate is less clear.
Depending on the diagnostic criteria used and the population screened, the prevalence of
GDM ranges from 1.1 to 25.5 percent of pregnancies in the United States.2-4 In 2009 the Centers
for Disease Control and Prevention reported a prevalence of 4.8 percent of diabetes in
pregnancy. An estimated 0.5 percent of these cases likely represented women with pregestational
diabetes. Data from the international Hyperglycemia and Adverse Pregnancy Outcome (HAPO)
Study3 indicate that 6.7 percent of the women met a fasting plasma glucose threshold of 95
mg/dL (5.3 mmol/L), which is in keeping with the Carpenter and Coustan5 (CC) criteria that are
in common practice in North America. In contrast, 17.8 percent of women were diagnosed with
GDM using the International Association of Diabetes in Pregnancy Study Groups (IADPSG)
criteria in which lower glucose thresholds are proposed to diagnose GDM.
The prevalence of GDM is not only influenced by diagnostic criteria but also by population
characteristics. In a recent publication, data from the HAPO study demonstrate wide variability
in GDM prevalence across a variety of study centers internationally and within the United States,
even when the same diagnostic criteria are applied (i.e., IADPSG).6 Prevalence in the United
States ranged from 15.5 percent in Providence, RI, to 25.5 percent in Bellflower, CA. There are
ethnic differences in the prevalence of GDM in the United States. Native American, Asian,
Hispanic, and African-American women are at higher risk than non-Hispanic white women
based on CC criteria and/or hospital discharge diagnosis.7 Data from 2000 showed that
prevalence was highest among Asian and Hispanic women (~7 to 8 percent), intermediate among
African-American women (~6 percent), and lower among non-Hispanic white women (~5
percent). The rate of increase of prevalence over the past 10 years has been highest for Asian and
African-American women. A report from Montana demonstrated that the prevalence of GDM
increased by approximately 10 percent among white women and by approximately 21 percent
among Native American women from 2000 to 2003.7
The incidence of GDM has increased over the past decades in parallel with the increase in
rates of obesity and type 2 diabetes mellitus, and this trend is expected to continue. In 2001 in the
United States, the prevalence of obesity (body mass index [BMI] ≥30) was 20.9 percent and the
prevalence of diabetes was 7.9 percent.8 It is unclear how much the increase in obesity will
impact the proportion of women diagnosed with overt diabetes during pregnancy versus transient
pregnancy induced glucose intolerance.9
GDM is usually diagnosed after 20 weeks’ gestation when placental hormones that have the
opposite effect of insulin on glucose metabolism increase substantially. Women with adequate
insulin secreting capacity overcome this insulin resistance of pregnancy by secreting more
endogenous insulin in order to maintain normal blood glucose. Women with less adequate
pancreatic reserve are unable to produce adequate insulin to overcome the increase in insulin
resistance, and glucose intolerance results.
1
Glucose abnormalities in women with GDM usually resolve postpartum, but commonly recur
in subsequent pregnancies. Women with GDM have an increased risk of future development of
overt diabetes. The cumulative incidence of diabetes after a diagnosis of GDM varies widely
depending on maternal BMI, ethnicity, and time since index pregnancy, and may reach levels as
high as 60 percent.10 When glucose abnormalities persist postpartum in a woman with GDM, her
diabetes is recategorized as overt diabetes. When this occurs, the possibility that this woman had
pregestational (i.e., overt) diabetes increases, especially if the diagnosis of GDM occurred prior
to 20 weeks’ gestation and glucose levels were markedly elevated in pregnancy.
The increased rates of obesity and type 2 diabetes mellitus, particularly among young
females, makes it increasingly important to distinguish the effect of obesity and pregestational
diabetes from GDM.11,12 There is considerable variability in the proportion of women with
suspected pregestational diabetes among studies that investigate pregnancy outcomes of women
with GDM. This contributes to the confusion surrounding the true morbidity of GDM. In an
attempt to enable better comparability across future studies and more accurate risk stratification
of pregnant women with diabetes, recommendations13 have proposed the exclusion of women
with more severe glucose abnormalities in pregnancy from the diagnosis of GDM in an attempt
to exclude women with pregestational (i.e., overt diabetes) from the population of women
defined as having GDM. This proposal is in contrast to the older definition of GDM as any
degree of glucose intolerance first discovered in pregnancy.
Risk Factors
Risk factors for GDM include greater maternal age, higher BMI, member of an ethnic group
at increased risk for development of type 2 diabetes mellitus (i.e., Hispanic, African, Native
American, South or East Asian, or Pacific Inlands ancestry), polyhydramnios, past history of
GDM, macrosomia in a previous pregnancy, history of unexplained stillbirth, type 2 diabetes
mellitus in a first degree relative, polycystic ovary syndrome, and metabolic syndrome.14 Low
risk of GDM is usually defined as young (age less than 25 or 30 years), non-Hispanic white,
normal BMI (25 kg/m2 or less), no history of previous glucose intolerance or adverse pregnancy
outcomes associated with GDM, and no first degree relative with known diabetes.7,15 Women at
high risk of GDM are usually defined as having multiple risk factors for GDM. Women at
moderate risk of GDM do not satisfy all criteria of women at low risk, but they lack two or more
risks for GDM.
Screening and Diagnostic Strategies
The 2008 U.S. Preventive Services Task Force (USPSTF) evidence review on screening for
GDM concluded that, at that time, “evidence was insufficient to assess the balance of benefits
and harms of screening for gestational diabetes mellitus either before or after 24 weeks’
gestation.”16 The report suggested that “…until there was better evidence clinicians should
discuss screening for GDM with their patient and make case-by-case decisions. Discussions
should include information about the uncertainty of benefits and harm as well as the frequency of
positive screening test results.”
The 2001 practice guidelines of the American College of Obstetricians and Gynecologists
(ACOG) endorsed risk factor-based screening for GDM, recognizing that low risk women may
be less likely to benefit from screening with glucose measurements. Women were considered
low risk of GDM if they met all the following criteria: (1) younger than 25 years; (2) not a
member of an ethnic group at high risk for development of type 2 diabetes mellitus; (3) BMI of
2
25 kg/m2 or less; (4) no history of previous glucose intolerance or adverse pregnancy outcomes
associated with GDM; and (5) no first degree relative with known diabetes. AGOG will update
their 2001 practice guidelines on GDM based on the proceedings of the 2012 National Institutes
of Health consensus conference on GDM diagnosis. Until 2011 the American Diabetes
Association (ADA) also endorsed no screening for pregnant woman who met all the criteria
mentioned above for low risk of GDM. In 2011 the ADA changed their recommendations to
endorse glucose testing for GDM in all pregnant women who do not have a diagnosis of
pregestational diabetes.
Common practices of glucose screening for GDM in North America involve a two-step
approach in which patients with abnormal results on a screening test receive a subsequent
diagnostic test.17 Typically, a 50 g oral glucose challenge test (OGCT) is initially administered
between 24 and 28 weeks’ gestation in a nonfasting state, in women at moderate risk (i.e.,
women who do not meet all low risk criteria but lack two or more risk factors for GDM). The
test is administered earlier in gestation for women at high risk of GDM (i.e., multiple risk factors
for GDM) and repeated at 24-28 weeks’ gestation if initial surveillance is normal. Patients who
meet or exceed a screening threshold (usually 130 mg/dL or 140 mg/dL) receive a more involved
diagnostic test, the oral glucose tolerance test (OGTT) in which a 75 g or 100 g oral glucose load
is administered in a fasting state, and plasma glucose levels are evaluated after 1, 2, or 3 hours. A
diagnosis of GDM is made in pregnant women when one or more glucose values fall at or above
the specified glucose thresholds. Alternatively, a one-step method in which all patients or high
risk patients forego the screening test and proceed directly to the OGTT has been
recommended.18 Interest has grown in assessing the usefulness of fasting plasma glucose as an
alternative to the OGCT for screening for GDM for a number of reasons. First, the IADPG has
proposed the use of a high threshold fasting plasma glucose 126 mg/dL (7.0 mmol/L) as soon as
pregnancy is confirmed in women at high risk of type 2 diabetes mellitus as a means of
identifying women with overt diabetes that likely predates their pregnancy. It is hypothesized
that lesser degrees of fasting glucose elevation could be used to screen for GDM if this test is
already being done to rule out overt diabetes. However, fasting glucose in early pregnancy is not
well studied. Second, the reproducibility of fasting glucose measurement is superior to post
glucose load measurements.149 Third, some women do not tolerate the oral glucose drinks.
The absence of a universally accepted “gold standard” for the diagnosis of GDM has resulted
in a variety of recommended diagnostic glucose thresholds that have been endorsed by different
stakeholders (Table 1; Figure 1). These criteria reflect changes that have occurred in laboratory
glucose measurements over the years, and new evidence that suggests the ability of different
glucose thresholds to predict poor pregnancy outcomes. The different diagnostic criteria and
thresholds result in different estimates of prevalence of GDM.
In 2004, a cross-sectional study reported that universal screening was the most common
practice in the United States with 96 percent of obstetricians routinely screening for GDM.19 In
contrast, the guidelines of ACOG and the ADA at that time stated that women at low risk for
GDM were unlikely to benefit from screening.17,20 Since only 10 percent of pregnant women
were categorized as low risk, some argued that selective screening contributed to confusion with
little benefit and potential for harm.21 Of particular concern was the association between risk
factor-based screening and high rates of false negative results.22 Others have endorsed alternative
risk scoring systems for screening.23
The IADPSG, an international consensus group with representation from multiple obstetrical
and diabetes organizations, recently spearheaded a re-examination of the definition of GDM in
3
an attempt to bring uniformity to GDM diagnoses.24 The IADPSG recommended that a one-step
75 g OGTT be given to all pregnant women who do not have a diagnosis of overt diabetes. They
also recommended that a single glucose value, rather than at least two abnormal values at or
above diagnostic glucose thresholds on the OGTT be accepted as sufficient for a diagnosis of
GDM. The diagnostic glucose thresholds recommended by the IADPSG were the maternal
glucose values from the HAPO study3 that identified a 1.75-fold increase (adjusted odds ratio
relative to the mean cohort glucose values) in large for gestational age, elevated C-peptide, high
neonatal body fat, or a combination of these factors. Since overt diabetes is often asymptomatic,
may not have been screened for prior to conception, has a prevalence that is increasing
dramatically in reproductive age women, and carries a higher risk for poor pregnancy outcomes,
the IADPSG also recommended that all or at least women from high risk groups for type 2
diabetes mellitus be screened for overt diabetes at their first prenatal visit and excluded from the
diagnosis of GDM using one of the following criteria: fasting plasma glucose ≥126 mg/dL (7.0
mmol/L), glycated hemoglobin (HbA1c) ≥6.5 percent (Diabetes Chronic Complications
Trial/United Kingdom Prospective Diabetes Study standardized), or a random plasma glucose
≥200 mg/dL (11.1 mmol/L) confirmed by one of the first two measures.25
Figure 1. Comparison of different diagnostic thresholds for GDM
ADA = American Diabetes Association, CC = Carpenter-Coustan, CDA = Canadian Diabetes Association, dL= deciliter,
g = grams, IADPSG = International Association of Diabetes in Pregnancy Study Groups, L= liter; mg = milligrams,
mmol = millimoles; NDDG = National Diabetes Data Group, WHO = World Health Organization
Note: This figure presents the various diagnostic criteria for GDM. The top bar compares fasting glucose diagnostic thresholds.
The bottom bar compares post glucose load diagnostic thresholds. The criteria are arranged from left (green) to right (red) from
the lowest diagnostic glucose thresholds to the highest. The post glucose load bar is not entirely comparable because different
glucose loads were used as indicated. The bottom part of each box shows which diagnostic thresholds were accepted by various
organizations over the years including any modifications to the criteria. For example, ADA 2000 to 2010 endorsed the CC
diagnostic thresholds on a 75g or 100g OGTT.
4
Table 1. Diagnostic criteria and plasma glucose thresholds for GDM
Year
Organization
ADA
ADA
Low risk† excluded
IADPSG
ADA
1. CC
th
2. 4 IWC (same)
th
3. 5 IWC (same as
th
4 but 75 g accepted
with same glucose
thresholds)
1999
26
2000-2010
2011-2012
50 g OGCT
1
100 g OGTT
2 or more
50 g OGCT
1
100 g or 75 g
OGTT after
overnight fast ≥8
hr
2 or more
0 (h)
—
105 mg/dL
5.8 mmol/L
—
13,27-36
37
5
1. 1982
38
2. 1998
39
3. 2007
40
NDDG
1979
WHO
1999 WHO
41
consultation
WHO
Abnormal
Value(s)
Testing
Schedule
1985 WHO
study group
42
report
75 g OGTT
1 or more
50 g OGCT
1
100 g OGTT
2 or more
50 g OGCT
100 g OGTT
75 g OGTT
75 g OGTT
95 mg/dL
5.3 mmol/L
92 mg/dL
5.1 mmol/L
—
—
2 or more
Threshold (Equal to or Greater Than)
1 (h)
2 (h)
3 (h)
140 mg/dL
—
—
7.8 mmol/L
190 mg/dL
165 mg/dL
145 mg/dL
10.5 mmol/L
9.1 mmol/L
8.0 mmol/L
130 mg/dL
7.2 mmol/L
or
—
—
140 mg/dL
7.8 mmol/L
140 mg/dL
7.8 mmol/L
180 mg/dL
155 mg/dL
10.0 mmol/L
8.6 mmol/L
(3 hr value only
for 100-g test)
180 mg/dL
153 mg/dL
—
10.0 mmol/L
8.5 mmol/L
130 mg/dL
—
—
7.2 mmol/L
95 mg/dL
5.3 mmol/L
180 mg/dL
10.0 mmol/L
155 mg/dL
8.6 mmol/L
140 mg/dL
7.8 mmol/L
—
105 mg/dL
5.8 mmol/L
—
190 mg/dL
10.5 mmol/L
—
165 mg/dL
9.1 mmol/L
140 mg/dL
7.8 mmol/L for
IGT of pregnancy;
200 mg/dL
11.1 mmol/L for
Dx of DM
7.8 mmol/L (140
mg/dL); for IGT of
pregnancy; 200
(11.1 mmol/L) for
Dx of DM
—
145 mg/dL
8.0 mmol/L
1
6.1 mmol/L for
IGT of
pregnancy;
7.0 mmol/L for
Dx of DM
—
1
7.8 mmol/L
140 mg/dL for
IGT of
pregnancy
—
5
—
—
Table 1. Diagnostic criteria and plasma glucose thresholds for GDM (continued)
Organization
CDA
ACOG – risk factor
th
4 IWC
rd
3 IWC
ADIPS
Testing
Schedule
Year
2003, 2008
2001
1991
1998
43,44
Abnormal
Value(s)
50 g OGCT
1
75 g
2 or more
50 g
1
100 g CC
2 or more
100 g NDDG
2 or more
100 g OGTT
2 or more
50 g or 75 g
nonfasting
1
75 g fasting
1
0 (h)
—
95 mg/dL
5.3 mmol/L
—
17,45
46
95 mg/dL
5.3 mmol/L
105 mg/dL
5.8 mmol/L
105 mg/dL
5.8 mmol/L
—
47
99 mg/dL
5.5 mmol/L
6
Threshold (Equal to or Greater Than)
1 (h)
2 (h)
140 mg/dL
7.8 mmol/L
or
—
186 mg/dL,
10.3 mmol/L Dx
GDM
191 mg/dL
160 mg/dL
10.6 mmol/L
8.9 mmol/L
130 mg/dL
7.2 mmol/L
or
—
140 mg/dL
7.8 mmol/L
180 mg/dL
155 mg/dL
10.0 mmol/L
8.5 mmol/L
190 mg/dL
165 mg/dL
10.5 mmol/L
9.1 mmol/L
190 mg/dL
165 mg/dL
10.5 mmol/L
9.1 mmol/L
140 mg/dL
7.8 mmol/L (50 g)
or
—
144 mg/dL
8.0 mmol/L (75 g)
144 mg/dL
8.0 mmol/L
or 1
—
62 mg/dL
9.0 mmol/L*
3 (h)
—
—
—
140 mg/dL
7.8 mmol/L
145 mg/dL
8.0 mmol/L
145 mg/dL
8.0 mmol/L
—
—
Table 1. Diagnostic criteria and plasma glucose thresholds for GDM (continued)
Threshold (Equal to or Greater Than)
1 (h)
2 (h)
3 (h)
162 mg/dL
48
EASD
1996
75 g
1
—
—
9.0 mmol/L
130 mg/dL
7.2 mmol/L
Risk Assessment
or
—
—
1
—
USPSTF (Grade 1
50 g OGCT
2008‡
140 mg/dL
recommendation)
7.8 mmol/L
100 g OGTT
2 or more
NR
NR
NR
NR
ACOG = American College of Obstetricians and Gynecologists, ADA = American Diabetes Association, ADIPS = Australasian Diabetes in Pregnancy Society, CC = Carpenter,
Coustan, CDA = Canadian Diabetes Association, DM = diabetes mellitus, Dx = diagnosis, EASD = European Association for the Study of Diabetes, h = hours; IADPSG =
International Association of Diabetes in Pregnancy Study Groups, IGT = impaired glucose tolerance, IWC = International Workshop Conference, NDDG = National Diabetes Data
Group, NR = not reported, OGCT = oral glucose challenge test, OGTT = oral glucose tolerance test, USPSTF = U.S. Preventive Services Task Force, WHO = World Health
Organization
†Low risk defined as: (1) age <25 yr, (2) normal body weight, (3) no first degree relative with DM, (4) no history of abnormal glucose, (5) no history of poor obstetrical outcomes,
(6) not of high-risk ethnicity for DM.
*In New Zealand.
‡ Screening for gestational diabetes mellitus: U.S. Preventive Services Task Force recommendation statement. Annals of Internal Medicine 2008;148(10):759-65.
Organization
Year
Testing
Schedule
Abnormal
Value(s)
0 (h)
108 mg/dL
6.0 mmol/L
7
Treatment Strategies
Initial treatment for GDM involves diet modification, glucose monitoring, and moderate
exercise. When dietary management does not achieve desired glucose control, insulin or oral
antidiabetic medications may be used.49 Increased prenatal surveillance may also occur as well as
changes in delivery management depending on fetal size and the effectiveness of measures to
control glucose.
The 2008 USPSTF report found that treatment of women with mild GDM (excluding women
who met World Health Organization criteria for overt diabetes) diagnosed after 24 weeks’
gestation provided benefits in terms of maternal and neonatal health outcomes.16 Specifically,
they found evidence from a high quality trial involving 1,000 women showing a reduction in
“any serious perinatal complication” which included death, shoulder dystocia, bone fracture, and
nerve palsy.50 The number of events for many of the individual outcomes was extremely small,
which did not provide adequate evidence to make conclusions for individual outcomes. The same
study showed a reduction in maternal hypertension.50 Further, among a subset of survey
respondents, mothers who received treatment were less depressed at 3 months and data showed a
trend to better quality of life compared with women who did not receive treatment.50
The USPSTF report found no evidence of harms of treatment, although the available
evidence was sparse and the review authors observed that these events may be rare and may not
be observed in trials.16 Potential harms of treatment may include small for gestational age
neonates, maternal stress, and additional costs including those associated with laboratory testing
as well as patient and clinician time.51 Clinician time can include the physician as well as
diabetes educators, nutritionists, and other providers of obstetrical care. Healthcare provider
anxiety over the diagnosis of GDM is a potential harm that could result in additional, and
possibly unnecessary or overly aggressive, fetal, and neonatal surveillance and delivery
management. Evidence suggests that the label of GDM, regardless of need, appears to influence
the care provided as evidenced by higher neonatal intensive care unit admission rates for the
newborn babies of women treated for GDM.52
Scope and Key Questions
Scope of the Review
Based on systematic reviews published in 2003 and 2008, the USPSTF concluded that there
was insufficient evidence upon which to make a recommendation regarding routine screening of
all pregnant women for gestational diabetes.16,53 However, several key studies have been
published since the 2008 report.3,9,54 The National Institutes of Health Office of Medical
Applications of Research (OMAR) commissioned this report (Key Questions 3 to 5, see section
below) and it was conducted by the Agency for Healthcare Research and Quality (AHRQ)
Evidence-based Practice Center (EPC) Program. OMAR will use the review to inform a
consensus meeting and guideline development. The USPSTF joined this effort and will use the
review to update its recommendation on screening for GDM (Key Questions 1 and 2 below).
The primary aims of this review were to: (1) identify the test properties of screening and
diagnostic tests for GDM, (2) evaluate the potential benefits and harms of screening at ≥24
weeks and <24 weeks’ gestation,(3) assess the impact of different screening and diagnostic
thresholds on outcomes for mothers and their offspring, and (4) determine the effects of
8
treatment in modifying outcomes for women diagnosed with GDM. The benefits and harms of
treatments will be considered in this review in order to determine the downstream effects of
screening on health outcomes. The intent of this review was also to assess whether evidence gaps
of the previous USPSTF reviews have been filled. These gaps included lack of sufficient
evidence to determine whether maternal or fetal complications are reduced by screening; lack of
screening studies with adequate power to evaluate health outcomes such as mortality, NICU
admissions, hyperbilirubinemia; limited evidence on the accuracy of screening strategies; and
insufficient evidence on the benefits of treating GDM in improving health outcomes.
Key Questions
The Key Questions for this evidence synthesis were developed by OMAR and the USPSTF
to inform consensus meetings and guideline development (OMAR specifically developed Key
Questions 3 to 5). Investigators from the University of Alberta EPC worked in consultation with
representatives from AHRQ, OMAR and the USPSTF, and a panel of technical experts to
operationalize the Key Questions. The technical expert panel provided content and
methodological expertise throughout the development of this evidence synthesis. Participants of
this panel are identified in the front matter of this report. The Key Questions are as follows:
Key Question 1: What are the sensitivities, specificities, reliabilities, and yields of current
screening tests for GDM? (a) After 24 weeks’ gestation? (b) During the first trimester and up to
24 weeks’ gestation?
• Population: Pregnant women (≥24 weeks’ gestation and <24 weeks’ gestation) without
known preexisting diabetes mellitus (DM)
• Interventions: Any screening or diagnostic test, including one-step, two-step, or other
approach
• Comparators: Any reference standard
• Outcomes: Sensitivity, specificity, positive predictive value, negative predictive value,
reliability (i.e., accuracy), and yield (i.e., prevalence)
• Timing: Any duration of followup
• Settings: All settings
Key Question 2: What is the direct evidence on the benefits and harms of screening women
(before and after 24 weeks’ gestation) for GDM to reduce maternal, fetal, and infant morbidity
and mortality?
• Population: Pregnant women (≥24 weeks’ gestation and <24 weeks’ gestation) without
known preexisting DM
• Interventions: Any screening or diagnostic test, including one-step, two-step, or other
approach; if diagnosed with GDM, any treatment
• Comparators: No test for GDM
• Outcomes: Maternal, fetal, and infant morbidity and mortality
• Timing: Any duration of followup
• Settings: All settings
Key Question 3: In the absence of treatment, how do health outcomes of mothers who meet
various criteria for GDM and their offspring compare to those who do not meet the various
criteria?
9
•
Population: Pregnant women (≥24 weeks’ gestation and <24 weeks’ gestation) without
known preexisting DM who meet different test thresholds for GDM
• Interventions: None
• Comparators: Pregnant women (≥24 weeks’ gestation and <24 weeks’ gestation) without
known preexisting DM who do not meet specific test thresholds for GDM
• Outcomes:
o Maternal
− Short-term: preeclampsia/maternal hypertension, cesarean delivery
(elective and medically indicated), depression, birth trauma, mortality,
weight gain
− Long-term: type 2 DM risk, obesity, hypertension
o Fetal/neonatal/child
− Short-term: macrosomia, shoulder dystocia, clavicular fracture, brachial
plexus injury (permanent and transient), birth injury, hypoglycemia,
hyperbilirubinemia, mortality
− Long-term: obesity, type 2 DM, transgenerational GDM
• Timing: Any duration of followup
• Settings: All settings
Key Question 4: Does treatment modify the health outcomes of mothers who meet various
criteria for GDM and offspring?
• Population: Pregnant women (≥24 weeks’ gestation and <24 weeks’ gestation) without
known preexisting DM who meet any diagnostic threshold for GDM
• Interventions: Any treatment for GDM including, but not limited to, dietary advice, blood
glucose monitoring, insulin therapy, and oral hypoglycemic agents
• Comparators: Placebo or no treatment
• Outcomes:
o Maternal
− Short-term: preeclampsia/maternal hypertension, cesarean delivery
(elective and medically indicated), depression, birth trauma, mortality,
weight gain
− Long-term: type 2 DM risk, obesity, hypertension
o Fetal/neonatal/child
− Short-term: macrosomia, shoulder dystocia, clavicular fracture, brachial
plexus injury (permanent and transient), birth injury, hypoglycemia,
hyperbilirubinemia, mortality
− Long-term: obesity, type 2 DM, transgenerational GDM
• Timing: Any duration of followup
• Settings: All settings
Key Question 5: What are the harms of treating GDM and do they vary by diagnostic approach?
• Population: Pregnant women (≥24 weeks’ gestation and <24 weeks’ gestation) without
known preexisting DM who meet any diagnostic threshold for GDM
• Interventions: Any treatment for GDM including, but not limited to, dietary advice, blood
glucose monitoring, insulin therapy, and oral hypoglycemic agents
• Comparators: Placebo or no treatment
10
•
Outcomes: Harms, including anxiety, healthcare system issues, burden on practitioner’s
office, increased interventions due to treatment bias (e.g., increased cesarean sections
resulting from bias of caregivers toward expectation of adverse outcomes), postpartum
depression, SGA, costs, and resource allocations
• Timing: Any duration of followup
• Settings: All settings
We developed an analytic framework (Figure 2) to describe the path from screening pregnant
women to the potential benefits and harms of treatment. The figure illustrates the clinical
concepts and mechanism by which screening and treatment for GDM may result in beneficial or
adverse maternal and fetal/neonatal/child outcomes. The figure also indicates the relation
between the Key Questions and the specific links along the pathway from screening to final
outcome.
11
Figure 2. Analytic framework for screening and diagnosing GDM
Note: The circled numbers correspond to the Key Questions.
AE = adverse event, GDM = gestational diabetes mellitus
12
Methods
The methods of this evidence synthesis are based on the methods outlined in the Agency for
Healthcare Research and Quality (AHRQ) Methods Guide for Effectiveness and Comparative
Effectiveness Reviews (www.effectivehealthcare.ahrq.gov/methodsguide.cfm) and the U.S.
Preventive Services Task Force (USPSTF) Procedure Manual
(www.uspreventiveservicestaskforce.org/uspstf08/methods/procmanual.pdf). The main sections
in this chapter reflect the elements of the protocol established for the review. The methods and
analyses were determined a priori, except where otherwise specified.
Topic Refinement and Technical Expert Panel
The National Institutes of Health Office of Medical Applications of Research (OMAR)
commissioned this report and it was conducted by AHRQ through the Evidence-based Practice
Center (EPC) Program. The Key Questions were developed by OMAR (Key Questions 3 to 5)
and the USPSTF. OMAR will use the review to inform a consensus meeting and guideline
development. The USPSTF joined this effort and will use the review to update its
recommendation on screening for gestational diabetes mellitus.
Investigators from the University of Alberta EPC worked in consultation with representatives
from AHRQ, OMAR and the USPSTF, and a panel of Technical Experts to operationalize the
Key Questions. The Technical Expert Panel provided content and methodological expertise
throughout the development of this evidence synthesis.
Literature Search Strategy
Our research librarian systematically searched the following bibliographic databases for
studies published from 1995 to May 2012: MEDLINE® Ovid, Ovid MEDLINE® In-Process &
Other Non-Indexed Citations, Cochrane Central Register of Controlled Trials (contains the
Cochrane Pregnancy and Childbirth Group, which hand searches journals pertinent to its content
area and adds relevant trials to the registry), Cochrane Database of Systematic Reviews (CDSR),
Database of Abstracts of Reviews of Effects (DARE), Global Health, Embase, Pascal CINAHL
Plus with Full Text (EBSCO host), BIOSIS Previews® (Web of KnowledgeSM), Science Citation
Index Expanded® and Conference Proceedings Citation Index- Science (both via Web of
ScienceSM), PubMed®, LILACS (Latin American and Caribbean Health Science Literature),
National Library of Medicine (NLM) Gateway, and OCLC ProceedingsFirst and PapersFirst. We
searched trial registries, including the WHO International Clinical Trials Registry Platform
(ICTRP), ClinicalTrials.gov, and Current Controlled Trials.
We limited the search to trials and cohort studies published in English. For the search
strategies, the research librarian developed a combination of subject headings and keywords for
each electronic resource (see Appendix A for the detailed search strategies). The search
strategies were not peer reviewed.
We searched the Web sites of relevant professional associations and research groups,
including the American Diabetes Association, International Association of the Diabetes in
Pregnancy Study Groups, International Symposium on Diabetes in Pregnancy, and Australasian
Diabetes in Pregnancy Society for conference abstracts and proceedings from the past 3 years.
We reviewed the reference lists of relevant reviews (including the 2008 USPSTF review) and
included studies to identify additional studies.
13
We used Reference Manager® for Windows version 11.0 (2004–2005 Thomson
ResearchSoft) bibliographic database to manage the results of our literature searches.
Inclusion and Exclusion Criteria
The research team developed the review eligibility criteria in consultation with the technical
expert panel. The inclusion and exclusion criteria are presented in Table 2. We included studies
only when less than 20 percent of enrolled women had a known history of pre-existing diabetes
or separate data were provided for women with no pre-existing diabetes.
We limited our eligibility criteria to studies published in English due to lack of translation
resources. This decision was made in consultation with the technical expert panel, which
expressed no concerns that limiting the search to English language would forfeit important
studies. We included studies that were published since 1995 in order to capture several key
studies that were published in the late 1990s.
Randomized controlled trials (RCTs), nonrandomized controlled trials (NRCTs), and
prospective and retrospective cohort studies were eligible for inclusion.
Table 2. Eligibility criteria for the review
Category
Criteria
Primary research published in English from 1995 onward. Full text reports available
Publication type
(abstracts and conference proceedings excluded).
Study designs
RCTs, NRCTs, PCS, RCS.
Pregnant women ≥24 weeks’ gestation or <24 weeks’ gestation, with no known history
Population
of pre-existing diabetes.
KQ1: Any GDM screening or diagnostic test vs. any GDM reference standard or other
screening or diagnostic test;
KQ2: Any GDM screening test vs. no GDM screening test;
KQ3: Women who meet various thresholds for GDM vs. those who do not meet
Comparators
various criteria for GDM, where women in both groups receive no treatment;
KQ4 and 5: Any treatment for GDM, including but not limited to dietary advice, blood
glucose monitoring, insulin therapy (all preparations), and oral hypoglycemic agents,
vs. placebo or no treatment.
KQ1: Sensitivity, specificity, predictive values, accuracy, and yield (i.e., prevalence)
KQ2: Maternal, fetal, and infant morbidity and mortality.
KQ3 and 4:
Maternal outcomes: Short-term: preeclampsia/maternal hypertension, cesarean
delivery (elective and medically indicated), depression, birth trauma, mortality,
weight gain; Long-term: type 2 DM risk, obesity, hypertension.
Fetal, neonatal, and child: Short-term: macrosomia, shoulder dystocia, clavicular
Outcomes
fracture, brachial plexus injury (permanent and transient), birth injury,
hypoglycemia, hyperbilirubinemia, mortality; Long-term: obesity, type 2 DM,
transgenerational GDM.
KQ5: Harms, including anxiety, healthcare system issues, burden on practitioner’s
office, increased interventions due to treatment bias, postpartum depression, SGA,
costs, and resource allocations.
Timing
Any duration of followup.
Setting
All settings are eligible.
DM = diabetes mellitus, GDM = gestational diabetes mellitus, KQ = Key Question, NRCT = nonrandomized controlled trials,
PCS = prospective cohort study, RCS = retrospective cohort study, RCT = randomized controlled trial, SGA = small for
gestational age
Study Selection
We assessed the eligibility of articles in two phases. In the first phase, two reviewers used
broad criteria to independently screen the titles, keywords, and abstracts (when available)
(Appendix B1). They rated each article as “include,” “exclude,” or “unclear.” We retrieved the
14
full text article for any study that was classified as “include” or “unclear” by at least one
reviewer. Two reviewers independently assessed each full text article using a detailed form
(Appendix B2). We resolved disagreements by discussion and consensus or third-party
adjudication.
Quality Assessment of Individual Studies
Two reviewers independently assessed the methodological quality of the studies and resolved
discrepancies by discussion and consensus. We tested each quality assessment tool on a sample
of studies and developed guidelines for assessing the remaining studies. In addition, we extracted
the source of funding for each study. For studies included in Key Questions 2 to 5, we
summarized the quality as “good,” “fair,” or “poor” based on assessments from the tools
described below.
Quality Assessment of Diagnostic Studies
We assessed the methodological quality of studies relevant to Key Question 1 using the
quality assessment of diagnostic accuracy studies (QUADAS)-2 checklist.55 The tool consists of
14 items addressing important common biases in diagnostic studies such as spectrum,
incorporation, verification, disease progression, and information biases. Individual items are
rated “yes,” “no,” or “unclear” (Appendix B3a).
Quality Assessment of Trials
We assessed the internal validity of RCTs and NRCTs using the Cochrane Collaboration
Risk of Bias tool (Appendix B3b). This tool consists of seven domains of potential bias
(sequence generation, allocation concealment, blinding or participants and personnel, blinding of
outcome assessment, incomplete outcome data, selective outcome reporting, and “other” sources
of bias) and a categorization of the overall risk of bias.
Each domain was rated as having “low,” “unclear,” or “high” risk of bias. We assessed the
blinding and incomplete outcome data items separately for subjective outcomes (e.g., depression
scale) and objective clinical outcomes (e.g., mortality). We reported any additional sources of
bias, such as baseline imbalances or design-specific risks of bias, in the “other” sources of bias
domain.
The overall risk of bias assessment was based on the responses to individual domains. If one
or more of the individual domains had a high risk of bias, we rated the overall score as high risk
of bias. We rated the overall risk of bias as low only if all components were assessed as having a
low risk of bias. The overall risk of bias was unclear in all other situations.
Quality Assessment of Cohort Studies
We used the Newcastle-Ottawa Quality Assessment Scale (Appendix B3c) to assess the
methodological quality of prospective and retrospective cohort studies. The scale comprises eight
items that evaluate three domains of quality: sample selection, comparability of cohorts, and
assessment of outcomes. Each item that is adequately addressed is awarded one star, except for
the “comparability of cohorts” item, for which a maximum of two stars can be given.
The overall score is calculated by tallying the stars. We considered a total score of 7 to 9
stars to indicate high quality, 4 or 6 stars to indicate moderate quality, and 3 or fewer stars to
indicate poor quality.
15
Data Extraction
We extracted data using a structured, electronic form and imported the data into a Microsoft
Excel™ 2007 spreadsheet (Microsoft Corp., Redmond, WA) (Appendix B4). One reviewer
extracted data, and a second reviewer checked the data for accuracy and completeness.
Reviewers resolved discrepancies by discussion and consensus or in consultation with a third
party. We extracted the following data: author identification, year of publication, source of
funding, study design, population (e.g., inclusion and exclusion criteria, number of patients
enrolled, study withdrawals, duration of followup), patient baseline characteristics (e.g., age,
race, ethnicity, weight, body mass index, previous diagnosis of gestational diabetes mellitus
(GDM), family history of diabetes, comorbidities, smoking prevalence), details of the screening
or diagnostic test and reference standard, glucose threshold for GDM, type of treatment, and
outcomes, including adverse events.
We reported outcomes only if quantitative data were reported or could be derived from
graphs. We did not include outcomes that were described only qualitatively (e.g., if study authors
reported that “there was no difference between the groups”) or for which only a p-value was
reported.
We planned to extract any cost-related data, including costs to patients, insurance, or health
care system, that were reported in the included studies. However, we did not search for cost
effectiveness studies or conduct cost-effectiveness analyses of different treatment strategies.
Studies that reported only costs and provided no other outcome data were not included in the
review.
When more than one publication reported the results of a single study, we considered the
earliest published report of the main outcome data to be the primary publication. We extracted
data from the primary publication first and then any additional outcome data reported in the
secondary publications.
Data Synthesis
We made the following assumptions and performed the following imputations to transform
reported data into the form required for analysis. We extracted data from graphs using the
measurement tool of Adobe Acrobat 9 Pro (Adobe Systems Inc., California, U.S.) when data
were not reported in text or tables. As necessary, we approximated means by medians and used
95% confidence intervals (CI), p-values, or inter-quartile ranges to calculate or approximate
standard deviations when they were not given. We calculated p-values when they are not
reported.56
For Key Question 1, we constructed 2x2 tables and calculated sensitivity, specificity, positive
and negative predictive values, accuracy (true positive plus true negative divided by the sum of
true positive, true negative, false positive, and false negative) and yield (i.e., prevalence) of the
screening or diagnostic tests. If studies were clinically homogenous, we pooled sensitivities and
specificities using a hierarchical summary receiver-operator curve and bivariate analysis of
sensitivity and specificity.57
We described the results of studies qualitatively and in evidence tables. For Key Questions
3to 5, we performed meta-analysis to synthesize the available data when studies were sufficiently
similar in terms of their study design, population, screening or diagnostic test, and outcomes.
This was done using the Mantel-Haenszel method for relative risks and the inverse variance
16
method for pooling mean differences. Due to the expected between-study differences, we
decided a priori to combine results using the random effects model.58
We measured statistical heterogeneity among studies using the I2 statistic. We considered an
2
I value of 75 percent or greater to represent substantial heterogeneity and did not pool studies
indicating substantial heterogeneity. When studies were not pooled due to substantial
heterogeneity, we performed subgroup analyses if the number of studies was sufficient to
warrant these analyses.59 Factors to be considered for subgroup analyses included glucose
thresholds for tests, type of treatment, maternal age, race or ethnicity, and weight or body mass
index, previous diagnosis of GDM, family history of diabetes, and comorbidities, which were
extracted from each study.
We used Review Manager Version 5.0 (The Cochrane Collaboration, Copenhagen,
Denmark) to perform meta-analyses. For dichotomous outcomes, we computed relative risks to
estimate between-group differences. If no event was reported in one treatment arm, a correction
factor of 0.5 was added to each cell of the 2x2 table in order to obtain estimates of the relative
risk. For continuous variables, we calculated mean differences for individual studies. We
reported all results with 95% CI.
Where possible, we assessed publication bias both visually using the funnel plot and
quantitatively using Begg’s60 and Egger’s61 tests. Review Manager version 5.0.22 (The Cochrane
Collaboration, Copenhagen, Denmark) and Stata version 7.0 (Stata Corp., College Station, TX)
were used for all these analyses. In the event that studies could not be pooled, a narrative
summary of the results was presented.
Strength of the Body of Evidence
Two independent reviewers graded the strength of evidence for major outcomes and
comparisons for Key Questions 3 and 4 using the EPC GRADE (Grading of Recommendations
Assessment, Development, and Evaluation) approach. We resolved discrepancies by discussion
and consensus. We graded the evidence for the following key outcomes: birth injury,
preeclampsia, neonatal hypoglycemia, maternal weight gain, and long-term metabolic outcomes
of the child and mother. We made a post hoc decision to grade shoulder dystocia and
macrosomia. These were not included in the protocol as outcomes that would be graded but were
felt by the clinical investigators to be important to grade.
For each outcome, we assessed four major domains: risk of bias (rated as low, moderate, or
high), consistency (rated as consistent, inconsistent, or unknown), directness (rated as direct or
indirect), and precision (rated as precise or imprecise). No additional domains were used.
Based on the individual domains, we assigned the following overall evidence grades for each
outcome for each comparison of interest: high, moderate, or low confidence that the evidence
reflects the true effect. When no studies were available or an outcome or the evidence did not
permit estimation of an effect, we rated the strength of evidence as insufficient.
To determine the overall strength of evidence score, we first considered the risk of bias
domain. RCTs with a low risk of bias were initially considered to have a “high” strength of
evidence, whereas RCTs with high risk of bias and well-conducted cohort studies received an
initial grade of “moderate” strength of evidence. Low quality cohort studies received an initial
grade of “low” strength of evidence. The strength of evidence was then upgraded or downgraded
depending on the assessments of that body of evidence on the consistency, directness, and
precision domains.
17
Applicability
We assessed the applicability of the body of evidence following the PICOTS (population,
intervention, comparator, outcomes, timing of outcome measurement, and setting) format used to
assess study characteristics. Factors that may potentially weaken the applicability of studies may
include study population factors (e.g., race or ethnicity, age, risk level of GDM [i.e., weight,
body mass index, previous GDM diagnosis, family history of diabetes], comorbidities), study
design (i.e., highly controlled studies [e.g., RCTs] vs. observational studies), setting (e.g.,
primary vs. tertiary care), and experience of care providers.
Peer Review and Public Commentary
Peer reviewers were invited to provide written comments on the draft report based on their
clinical, content, or methodologic expertise. Peer review comments on the draft report were
addressed by the EPC in preparation of the final draft of the report. Peer reviewers did not
participate in writing or editing of the final report or other products. The synthesis of the
scientific literature presented in the final report does not necessarily represent the views of
individual reviewers. The dispositions of the peer review comments are documented and will be
published 3 months after the publication of the Evidence Report.
Potential reviewers must disclose any financial conflicts of interest greater than $10,000 and
any other relevant business or professional conflicts of interest. Invited peer reviewers may not
have any financial conflict of interest greater than $10,000. Peer reviewers who disclose
potential business or professional conflicts of interest may submit comments on draft reports
through AHRQ’s public comment mechanism.
The draft report was posted for public commentary. Comments on the draft report were
considered by the EPC in preparing the final report.
18
Results
This chapter reports on the results of our literature review and synthesis. First, we describe
the results of our literature search and selection process. Description of the characteristics and
methodological quality of the studies follow. We present our analysis of the study results by Key
Question. Metagraphs and tables reporting the strength of evidence for key outcomes are
available within each applicable section. Within each metagraph, the studies that provided data
are indexed by the name of the first author. A list of abbreviations is provided at the end of the
report.
Several appendixes provide supporting information to the findings presented in this section.
Appendix C provides the quality assessment ratings by domain for each study. Appendix D
contains detailed evidence tables describing the study, characteristics of the population,
screening criteria or diagnostic tests used, details of treatment (where relevant), and outcomes. A
list of citations for the excluded and unobtained studies is available in Appendix E. Appendixes
are available at the Agency for Healthcare Research and Quality (AHRQ) Web site
www.effectivehealthcare.ahrq.gov/reports/final.cfm.
Results of Literature Searches
The search strategy identified 14,398 citations from electronic databases. Screening based on
titles and abstracts identified 598 potentially relevant studies. We identified 30 additional studies
by hand searching the reference lists from included studies. Using the detailed selection criteria,
151 studies met the inclusion criteria and 469 were excluded. Of the 151 studies, 26 were
identified as companion publications and 125 were unique studies (Figure 3). Of the 125 unique
studies, 28 were further excluded during data extraction due to a lack of comparison or outcome
of interest, leaving the total number of included studies at 97.
The most frequent reasons for exclusion were: (1) ineligible comparator (studies comparing
two or more treatments but lacking a control group; n = 227); (2) ineligible publication type
(abstracts, conference proceedings, studies published prior to 1995; n = 106); (3) ineligible study
design (studies other than randomized controlled trials [RCTs], nonrandomized controlled trials
[NRCTs], prospective cohort studies, and retrospective cohort studies; n = 11); (4) study did not
report prespecified outcomes of interest (lacking test properties for Key Question 1, specified
outcomes for Key Questions 3,4, and 5 including harms of screening or treatment; n = 34); (5)
duplicate publication (n = 10); (6) intervention not of interest (studies without evaluation of
screening tests or criteria, or treatments for gestational diabetes mellitus [GDM]; n = 12); and (7)
population was not of interest (if >20 percent of pregnant women enrolled in study had known
pre-existing diabetes without subgroup analysis; n = 15). In addition, for Key Question 1 only
prospective studies were eligible for inclusion; 54 retrospective cohort studies were excluded. A
complete list of excluded studies and reasons for exclusion is provided in Appendix E.
19
Figure 3. Flow diagram of study retrieval and selection
* Five studies addressed more than one Key Question, therefore the sum of studies addressing the Key Questions exceeds the
total number of studies.
20
Description of Included Studies
A total of 97 studies met the eligibility criteria for this review, including 6 RCTs, 63
prospective cohort studies, and 28 retrospective cohort studies. The studies were published
between 1995 and 2012 (median 2004). Studies were conducted in the United States (24
percent), Europe (23 percent), Asia (22 percent), the Middle East (20 percent), Australia (4
percent), Central and South America (3 percent), and Canada (4 percent). The source of funding
for the included studies was academic (23 studies, 24 percent), foundation or organization (17
studies, 18 percent), government (14 studies, 14 percent), “other” (such as the WHO, or nongovernmental organization; 8 studies, 10 percent), and industry (10 studies, 10 percent). Twentytwo studies presented more than one source of funding. Two studies reported no external source
of funding (2 percent), and 46 studies (47 percent) did not describe a source of funding.
Forty-eight studies (50 percent) analyzed women tested for GDM between 24-28 weeks, with
a OGCT taking place first and the OGTT following within 7 days.50,62-108 Thirty-one studies (32
percent) did not specify when screening or diagnostic procedures took place.54,109-137 Of the 31
studies, one scheduled testing between 24 and 28 weeks, with different undefined test points if
clinically warranted.138 Eighteen studies (18 percent) screened or tested within unique time
ranges.133,139-155 Of these, one study screened participants with a OGCT at 21-23 weeks followed
by a diagnostic OGTT at 24-28 weeks;140 another screened a group of participants after 37
weeks;146 one study screened before 24 weeks; 143 and one study screened women at risk
between 14-16 weeks with normal women screened at the usual 24-28 weeks.148 Remaining
studies generally provided broader screening times ranging from 21-32 weeks
gestation.139,142,144,145,150-152 Studies employing WHO criteria generally screened further into
gestation as only an OGTT was performed: one study screened at 28-32 weeks,149 one study
between 26-30 weeks,155 another between 25-30 weeks,154 and another study screened women at
high risk at 18-20 weeks and others at 28-30 weeks.147 One study using WHO criteria did not
specify the time of testing.133
The number of women enrolled in each study ranged from 32143 to 23,3163 (median 750).
The mean age of study participants was 30 years. The mean age was consistent among most
studies, although women of slightly younger mean age (23-28 years) were enrolled studies
originating from countries outside North America (India, Turkey, Hong Kong, United Arab
Emirates).113,114,144,156
When duration of followup was reported, it was often described as “until birth” or “to
delivery.”62,73,84,95,114,120,146,152 One study reported followup extending from the first prenatal visit
(<13 weeks) until a OGCT (26-29 weeks),139 one study within the first trimester until 24-28
weeks gestation,101 and another began at first antenatal booking which ranged from first trimester
through to the third in women who were present for antenatal care in late gestation.157 One study
followed women for 3 months postpartum;83 and two studies provided longer-term followup
extending to 5-7 years132 and 7-11 years, respectively.96 Remaining studies did not provide
specific details on duration of followup.
Methodological Quality of Included Studies
The methodological quality of each study was assessed by two independent reviewers. Our
approach to assessing study quality is described in the methods section. The consensus ratings
for each study and domains are presented in Appendix C, Tables C1, C2, and C3. Studies were
assessed using different tools depending on the Key Question and study design: for Key
21
Question 1, QUADAS-2 was used; for Key Questions 2 to 5, the Cochrane Risk of Bias tool was
used for RCTs and the Newcastle Ottawa Scale was used for cohort studies. The methodological
quality of studies is described in detail within the results section for each Key Question.
Key Question 1. What are the sensitivities, specificities, reliabilities, and
yields of current screening tests for GDM?
GDM is diagnosed by having one or several glucose values at or above set glucose thresholds
following an OGTT administered in the fasting state during pregnancy. Variations in glucose
dose, time intervals of glucose measurements, and diagnostic glucose threshold values exist
(Table 1). The most commonly used screening practice is a 50 g OGCT without regard to timing
of last meal; plasma glucose is measured 1-hour after the glucose challenge. This was first
proposed by O’Sullivan and Mahan158 and has been modified over the years. There are two
different glucose threshold values commonly used for this screen in North America: ≥140 mg/dL
(≥7.8 mmol/L) and ≥130 mg/dL (≥7.2 mmol/L). Clinical and historical risk factors and fasting
plasma glucose (FPG) are two other screening practices included in this current review.
Two related issues make it difficult to organize and analyze the studies that address Key
Question 1. First, there are several screening options (e.g., risk factor-based, universal), and
several techniques (e.g., glucola-based, fasting, postprandial). In addition, there is no ‘gold
standard’ for diagnosing GDM. There are five different, but commonly used, glucose-based
diagnostic measures that overlap in the criteria they use.
We grouped studies according to the comparator OGTT diagnosis practices that were used,
specifically glucose load, time intervals, and threshold values. These groupings include: 3-hour,
100 g OGTT using Carpenter and Coustan (CC) criteria; 3-hour, 100 g OGTT using National
Diabetes Data Group (NDDG) criteria; 2-hour, 75 g OGTT using American Diabetes
Association (ADA) (2000-2010) criteria, and, 2-hour, 75 g OGTT using WHO criteria (Table 1).
We present results of screening tests based on these groupings that included women who
underwent the 50 g OGCT screen (further subdivided by screening threshold ≥140 mg/dL and
≥130 mg/dL), fasting plasma glucose (FPG), clinical and historical risk factors, and other
screening criteria. This is followed by a section on studies that compared early and late screening
practices. The final section summarizes the evidence comparing different glucose loads for the
OGTT diagnostic tests. Forest plots present 2x2 data, sensitivity and specificity; summary tables
present prevalence, positive and negative predictive values (PPV, NPV), and accuracy for
individual studies.
Description of Included Studies
There were 51 studies (reported in 52 papers) that met the inclusion criteria for Key Question
1.
Two papers from the Tri-Hospital
group142 are included as they report on results for different screening practices.159,160 Studies
were conducted in a wide range of regions: 11 in North America,64,69,72,104,105,121,123,126,127,142,143 10
in Europe,62,65,66,68,108,115,119,125,151,153 12 in Asia,70,73,101,107,111,114,118,128,129,139,140,157 15 in the Middle
East,67,71,74-77,99,100,109,110,112,113,117,138,144 2 in South America,63,120 and 1 in Australia.124 All studies
were prospective cohort studies. A summary table of the study and patient characteristics of the
individual studies can be found in Appendix D.
The prevalence of GDM varied across studies. The variability is due to differences in study
setting (i.e., country), screening practices (e.g., universal vs. selective), and/or population
characteristics (e.g., race/ethnicity, age, body mass index [BMI], parity). The range of GDM
62-77,91,99-101,104,105,107-115,117-121,123-127,129,138-140,142-144,151,153,157
22
prevalence for each diagnostic criteria is as follows: CC/ADA (2000-2010) (100 g) 3.6 to 38.0
percent; National Diabetes Data Group (NDDG) 1.4 to 50.0 percent, ADA (2000-2010) (75 g)
from 2.0 to 19.0 percent, and WHO from 1.7 to 24.5 percent. Prevalence results for individual
studies are presented in the following sections.
Methodological Quality of Included Studies
We used the QUADAS-2 tool to assess the quality of the studies included in this review. The
tool comprises four key domains that discuss patient selection, index test, reference standard, and
flow of patients through the study and the timing of the index tests and reference standard (flow
and timing). The first part of QUADAS-2 concerns bias; the second part considers applicability
or concerns that the study does not match the review question. Figure 4 summarizes the
assessments for risk of bias and Figure 5 summarizes assessments of applicability. Detailed
assessments for each study are presented in Appendix C1.
The domain of patient selection was rated as low risk that the selection of patients introduced
bias for 53 percent of the studies. These studies were prospective cohort studies, most enrolled a
consecutive sample of patients, and most avoided inappropriate exclusions. However, 25 percent
of studies were rated as unclear due to inadequate description. Overall, 55 percent of studies
were assessed as having high concerns about applicability for this domain. This was primarily
because these studies were conducted in developing countries and used the WHO criteria to
diagnose GDM. The results of these studies may not be directly relevant to the population in the
United States.
The domain of the index test was generally rated as low risk that the conduct or interpretation
of the index test introduced bias (53 percent). For most studies, the screening test (i.e., the index
test) was conducted before the reference standard, and the threshold for the screening test was
pre-specified. Concern about applicability was assessed as low (82 percent).
The domain of the reference standard (i.e., the criteria used to confirm a diagnosis of GDM)
was generally rated as unclear risk that the conduct or interpretation of the reference standard
introduced bias (63 percent). For most studies the result of the screening test was used to
determine whether patients underwent further testing for GDM. Concern about applicability was
assessed as low (86 percent).
The domain of flow and timing was assessed as low risk of bias for 39 percent of the studies.
For most studies, the interval between the index test and reference standard was appropriate
according to the criteria used in the study. Most patients received the reference standard, and
received the same reference standard. However, in 35 percent of studies not all patients received
a confirmatory reference standard if the screening test was below a certain threshold. These were
assessed as unclear risk of bias.
23
Figure 4. QUADAS-2 assessment of risk of bias by domain
Figure 5. QUADAS-2 assessment of applicability by domain
24
Key Points
•
•
•
•
•
•
•
•
Comparisons between screening tests and diagnostic thresholds were difficult because of
the variety of different populations and different tests that were studied.
Prevalence of GDM varied across studies and the diagnostic criteria used. The range of
prevalence was: CC 3.6 to 38.0 percent; NDDG 1.4 to 50.0 percent; ADA (75 g) 2.0 to
19.0 percent; and WHO 1.7 to 24.5 percent.
The 50 g OGCT with the 130 mg/dL cutpoint has higher sensitivity when compared with
the 140 mg/dL cutpoint, however, specificity is lower (6 studies). Both thresholds have
high NPV but variable PPV across a range of GDM prevalence.
The use of a high cutoff for a diagnosis of GDM on an OGCT is supported by one study
that assessed a 50 g OGCT (≥200 mg/dL) with GDM confirmed using the CC criteria.
Sensitivity, specificity, PPV and NPV were all 100 percent.
Fasting plasma glucose at a threshold of ≥85 mg/dL has similar sensitivity to 50 g
OGCT; specificity is lower (4 studies).
There were sparse data to assess screening and diagnostic tests for GDM less than 24
weeks’ gestation.
Four studies compared a 75 g load with a 100 g load (reference standard) to diagnose
GDM. The prevalence of GDM ranged from 1.4 to 50 percent. Median sensitivity and
PPV were low; median specificity and NPV were high.
One study compared the IADPSG criteria with a two-step strategy. Sensitivity was 82
percent and specificity was 94 percent. Prevalence of GDM was 13.0 percent with
IADPSG criteria compared with 9.6 percent with the two-step strategy. PPV and NPV
were 61 percent and 98, respectively.
Detailed Synthesis
50 g OGCT Screening and GDM Diagnosis with 100 g OGTT
This section includes studies in which women underwent a 2-step practice that included
screening with a 50 g OGCT at 24 to 28 weeks followed by a 100 g OGTT to confirm a
diagnosis of GDM. The 50 g OGCT screening test is grouped by the two following diagnostic
confirmation criteria: CC and ADA (2000-2010) criteria and the NDDG criteria.
Carpenter and Coustan and ADA (2000-2010) Criteria
Description of Included Studies
Fourteen studies confirmed a diagnosis of GDM with a 100 g, 3-hour OGTT using CC/ADA
2000-2010 criteria (Appendix D).63,64,68,72,75-77,99,104,108,121,140,159,161 Ten studies used a universal
screening practice,63,64,68,72,76,77,108,121,159,161 three studies used a selective, risk-based screening
practice for an OGCT,75,99,140 and one study only included women with an abnormal OGCT.104
Six studies performed the OGTT on all women regardless of OGCT value,63,68,72,108,140,159 while
eight performed an OGTT in patients with a positive OGCT. 64,75-77,99,104,121,161
Studies were conducted in the United States,64,104,121 Canada,15 Iran,71,75-77 Brazil,63 France,108
Mexico,72 Switzerland,68 Thailand,140 and United Arab Emirates.99 The number of patients
analyzed ranged from 138 to 11,545. Maternal age was reported in 12 studies and the mean
25
ranged from 23.7 to 32.5 years. Mean BMI was reported in 10 studies and ranged from 23.3 to
29.6 kg/m2. One study included women tested at ≥20 weeks’ gestation. 121
Results
Nine studies provided data to estimate the test characteristics of a 50 g OGCT screening
tested at the 1-hour interval and cutoff value of ≥140 mg/dL.63,64,68,72,76,99,108,140,159 The accuracy
of the OGCT (i.e., the proportion of true positive and true negative results) was generally high
(median = 86.5 percent) and ranged from 66 to 94 percent (Table 3). Figure 6 presents the
sensitivities and specificities for the individual studies. The joint estimates of sensitivity and
specificity were 85 percent (95% CI, 76 to 90) and 86 percent (95% CI, 80 to 90). Hierarchical
summary receiver operator characteristic (HSROC) curves comparing the sensitivity and
specificity for all studies are presented in Appendix F. The prevalence of GDM ranged from 3.8
to 31.9 (Table 3). The PPV ranged from 18.5 to 83.1 percent; the NPV ranged from 95.1 to 99.0
percent (Table 3). The study by Rust et al. 121 included women ≥20 weeks and reported a
sensitivity of 56 percent (95% CI, 30 to 80) and specificity of 94 percent (95% CI, 91 to 96). The
prevalence of GDM was 3.6 percent.
Six studies used an OGCT cutoff value of ≥130 mg/dL.64,71,75-77,108 The accuracy of the
OGCT ranged from 64.5 to 90.4 (median = 78.5 percent) (Table 3). Figure 6 presents the
sensitivities and specificities for the individual studies. The joint estimates of sensitivity and
specificity were 99 percent (95% CI, 95 to 100) and 77 percent (95% CI, 68 to 83), respectively.
The prevalence of GDM ranged from 4.3 to 29.5 (Table 3). The PPV ranged from 10.7 to 62.3
percent; the NPV ranged from 97.3 to 100 percent (Table 3).
One study used an OGCT cutoff value of >200 mg/dL.104 The prevalence was 29.4 percent.
The sensitivity was 100 (95% CI, 0.87 to 100) and specificity was 100 percent (95% CI, 0.99 to
100).
The studies by Agarwal,99 Weerakiet,140 Bobrowski, 104 and Kashi75 are at high risk for
selection bias due to the use of selective screening practice. Not all women received a
confirmatory OGTT in the studies by Eslamian,71 Gandevani,76 Soheilykhah,77 and Yogev64 are
at high risk for partial verification bias.
26
Figure 6. Forest plot of sensitivity and specificity: 50 g OGCT by CC or ADA (2000–2010) criteria
ADA = American Diabetes Association; CC = Carpenter-Coustan; FN = false negative; FP = false positive; OGCT = oral glucose
challenge test; TN = true negative; TP = true positive
27
Table 3. Prevalence and diagnostic test characteristics for 50 g OGCT by CC or ADA (2000–2010) diagnostic criteria
Screening
Prevalence
PPV
NPV
Accuracy
Practice**
(%)
(95% CI)
(95% CI)
(%)
121
Rust, 1998
U.S.
448
Universal
3.6
24 (13-40)
98 (97-99)
92
63
Ayach, 2006
Brazil
341†
Universal
3.8
18 (10-31)
99(97-100)
86
108
Chevalier, 2011
France
11,545†
Universal
3.9
37 (34-40)
99 (99-100)
94
159
Trihospital, 1998
Canada
3,836†
Universal
6.9
23 (20-26)
97 (96-98)
82
64
Yogev 2004
U.S.
1,783
Universal
8.5
27 (24-32)
98 (97-99)
80
≥140 mg/dL OGCT
68
Perucchini, 1999
Switzerland
520†
Universal
10.2
43 (32-54)
95 (93-97)
88
72
De los Monteros, 1999 Mexico
445†
Universal
11.7
47 (38-57)
98 (96-99)
87
140
Weerakiet, 2006
Thailand
359†
Selective
16.7
32 (25-39)
97 (93-99)
66
76
Gandevani, 2011
Iran
585
Universal
22.2
62 (55-69)
96 (93-97)
85
99
Agarwal 2000
UAE
368
Selective
31.9
83 (80-89)
98 (96-99)
93
108
Chevalier, 2011
France
11,545†
Universal
4.3
31 (29-33)
100 (100-100)
90
64
Yogev 2004
U.S.
2,541
Universal
4.4
11 (9-13)
100 (99-100)
65
71
Eslamian, 2008
Iran
138
Universal
8.6
27 (16-42)
99 (95-100)
78
≥130 mg/dL OGCT
75
Kashi, 2007
Iran
200
Selective
10.0
31 (21-43)
100 (98-100)
78
76
Gandevani, 2011
Iran
585
Universal
22.2
51 (45-57)
100 (99-100)
79
77
Soheilykhah, 2011
Iran
1,502
Universal
29.5
62 (57-67)
97 (95-98)
82
Abnormal
104
≥200 mg/dL OGCT Bobrowski, 1996
U.S.
422†
6.4
100 (91-100) 100 (100-100) 100 (99-100)
screen**
CI = confidence interval; NPV = negative predictive value; OGCT = oral glucose challenge test; OGTT = oral glucose tolerance test, PPV = positive predictive value; UAE =
United Arab Emirates
*Number of women in the analysis.
**As reported in the methods of each study; all studies are 2-step screening and diagnosis.
†All women received both an OGCT and OGTT.
Diagnostic Test
Author, Year
Country
N*
28
NDDG Criteria
Description of Included Studies
Ten studies used the NDDG criteria to confirm a diagnosis of GDM (Appendix D).66,67,69,72Eight studies used a universal screening practice;66,67,69,72-74,144,159 two included
only women with an abnormal OGCT.104 123 Six studies performed the OGTT on all women
regardless of OGCT value,63,68,72,108,140,159 while the remaining studies performed an OGTT only
in patients with a positive OGCT.
Four studies were conducted in North America,69,104,123,159 two in Europe,74,144 and one each
in Mexico,72 Saudi Arabia,67 and Thailand,73 and Turkey.66 The number of patients enrolled
ranged from 80 to 4,274. Mean maternal age, reported in seven studies, ranged from 25.7 to 32.1
years. Only two studies reported BMI. All studies screened women after 24 weeks’ gestation.
74,104,123,144,159
Results
Seven studies provided data to estimate the test characteristics of a 50 g OGCT tested at the
1-hour interval and cutoff value of ≥140 mg/dL.66,69,72-74,144,159 The accuracy of the OGCT was
generally high (median = 82 percent) (Table 4). Figure 7 presents the sensitivities and
specificities for the individual studies. HSROC curves comparing the sensitivity and specificity
for all studies are presented in Appendix F. The joint estimates of sensitivity and specificity were
85 percent (95% CI, 73 to 92) and 83 percent (95% CI, 78 to 87), respectively. The prevalence of
GDM ranged from 1.4 to 45.8 (median = 6.2) (Table 4). The PPV ranged from 12.0 to 57.1; the
NPV ranged from 70 to 100 (Table 4).
Three studies67,74,113 used a cutoff ≥130 mg/dL. The accuracy of the test ranged from 50.0 to
85.5 percent (Table 4). Figure 7 presents the sensitivities and specificities for the individual
studies. As there were only three studies, we did not pool the results. The prevalence of GDM
ranged from 16.7 to 35.3 (Table 4). The PPV ranged from 20.0 to 75.0; the NPV ranged from
87.5 to 92.9 (Table 4). One study used an OGCT cutoff value of >200 mg/dL. The sensitivity,
specificity, PPV and NPV were all 100 percent.
The studies by Ardawi,67 Bobrowski,104 Berkus123 Cetin,144 Deerochanawong, 73 Lamar,69 and
Uncu,74 are at high or unclear risk for selection bias due to selective or unclear screening
practices. Studies by Ardawi,67 De los Monteros,72 and Lamar,69 are at high or unclear risk for
partial verification bias as not all women received a confirmatory OGTT.
29
Figure 7. Forest plot of sensitivity and specificity: 50 g OGCT by NDDG criteria
NDDG = National Diabetes Data Group; OGCT = oral glucose challenge test
Table 4. Prevalence and diagnostic test characteristics for 50 g OGCT by NDDG diagnostic criteria
Diagnostic
Test
Author, Year
Country
N*
Screening Prevalence
Practice**
(%)
PPV
(95%
CI)
NPV
(95% CI)
Accuracy
(%)
100 (9990
100)
Canada
3,836† Universal
3.8
15(12-17) 99 (98-99)
82
U.S.
136
NR
3.8
15 (6-33) 99 (95-100)
82
100 (9919 (14Spain
578
Universal
5.8
76
≥140 mg/dL
26)
100)
OGCT
26 (15144
Cetin, 1997
Turkey
274
Universal
6.2
97(95-99)
86
40)
De Los Monteros,
39 (30Mexico
445†
Universal
9.7
99 (97-99)
86
72
1999
49)
57 (3374
Uncu, 1995
Turkey
24†
Universal
45.8
70 (42-81)
63
79)
49 (34123
95 (85-98)
73
U.S.
80†
NR
26.3
Berkus, 1995
64)
≥130 mg/dL
74
Uncu, 1995
Turkey
18†
Universal
16.7
20 (6-51) 86 (56-96)
50
OGCT
Saudi
75 (6767
Ardawi, 2000
818
Universal
35.3
93 (88-96)
86
Arabia
82)
≥200 mg/dL
Abnormal
100 (91- 100 (100104
Bobrowski, 1996
U.S.
422†
6.4
100
OGCT
screen
100)
100)
CI = confidence interval; NDDG = National Diabetes Data Group; NPV = negative predictive value; NR = not reported; OGCT =
oral glucose challenge test; OGTT = oral glucose tolerance test; PPV = positive predictive value
*Number of women in the analysis.
**As reported in the methods of each study; all studies are 2-step screening and diagnosis.
†All women received both an OGCT and OGTT.
Deerochanawong,
73
1996
159
Trihospital, 1998
69
Lamar,1999
Perea-Carrasco,
66
2002
Thailand
709
Universal
30
1.4
12 (7-21)
50 g OGCT Screening and GDM Diagnosis with 75 g OGTT
This section includes studies in which women underwent a 2-step screening and diagnostic
practice that included a 50 g OGCT followed by a 75 g OGTT to confirm a diagnosis of GDM.
ADA (2000-2010) Criteria
Description of Included Studies
Three studies101,125,139 used the ADA 75 g, 2-hour criteria after a 50 g, 1-hour OGCT
(Appendix D). All but the study by Maegawa et al.101 used a threshold of ≥140 mg/dL for the
OGCT. The studies were conducted in Japan,101,139 and Germany.125 One Canadian study105
confirmed diagnosis using the Canadian Diabetes Association 75 g, 2-hour criteria.
The number of patients analyzed ranged from 509 to 912. All studies reported maternal age,
which ranged from 28.5 to 33.4 years. BMI ranged from 20.0 to 24.8 kg/m2. All studies
performed the OGCT screening at 24-28 weeks; two studies also screened women in early
pregnancy.101,139
Results
The accuracy of the ADA (2000-2010) 75 g ranged from 84 percent to 87 percent (Table 5).
Figure 8 presents the sensitivities and specificities for the individual studies. The results were not
pooled. The prevalence of GDM ranged from 1.6 to 18.1 (Table 5). The PPV ranged from 7 to
20; the NPV ranged from 99 to 100 (Table 5). The accuracy of the CDA 75 g was 72 percent;
PPV was 37 percent and NPV was 94 percent, respectively.
The studies by Rey105 and Yachi139 are at high or unclear risk of selection bias due to their
screening practices. The study by Buhling,125 is at high risk for partial verification bias as not all
women received a confirmatory OGTT.
Figure 8. Forest plot of sensitivity and specificity: 50 g OGCT (different thresholds) by ADA (2000–
2010) 75 g criteria
ADA = American Diabetes Association; CDA = Canadian Diabetes Association; OGCT = oral glucose challenge test; OGTT =
oral glucose tolerance test
31
Table 5. Prevalence and diagnostic test characteristics for 50 g OGCT (different thresholds) by
ADA (2000–2010) 75 g criteria
Author,
Screening Prevalence
PPV
NPV
Accuracy
Country
N*
Year
Practice**
(%)
(95% CI)
(95% CI)
(%)
Yachi,
Japan
509 Universal
1.6
7 (4-13)
100 (99-100)
79
139
2011
ADA (2000Maegawa,
Japan
749 Universal
2.9
17 (11-25) 99 (98-100)
87
101
2003
2010)
Buhling,
Germany
912 Universal
4.1
20 (15-27) 100 (99-100)
84
125
2004
Rey,
CDA
Canada
188† Selective
18.1
37 (25-51) 94 (87-97)
72
105
2004
ADA = American Diabetes Association; CDA = Canadian Diabetes Association; CI = confidence interval; NPV = negative
predictive value; OGCT = oral glucose challenge test, OGTT = oral glucose tolerance test; PPV = positive predictive value
*Number of women in the analysis.
**As reported in the methods of each study; all studies are 2-step screening and diagnosis.
†All women received both an OGCT and OGTT.
Organization
World Health Organization Criteria
Description of Included Studies
Four studies used the WHO criteria to confirm a diagnosis of GDM (Appendix D).62,70,73,157
The studies were conducted in Netherlands,62 Sri Lanka,70 Malaysia,157 and Thailand.73 The
number of patients enrolled ranged from 188 to 1,301. Mean maternal age ranged from 25.7 to
30.8 years. Mean BMI, as reported in two studies, was 22.4 and 24.2. All studies performed the
OGCT screening at 24-28 weeks with OGTT performed the following 1 to 2 weeks.
Results
The accuracy of the test ranged from 73 percent to 88 percent (Table 6). Figure 9 presents the
sensitivities and specificities for the individual studies. The results were not pooled. The
prevalence of GDM ranged from 3.7 to 15.7 (Table 6). The PPV ranged from 5 to 20; the NPV
ranged from 94 to 99 (Table 6). The prevalence of GDM ranged from 3.7 to 50.0 (Table 6). The
PPV ranged from 17.8 to 76.2; the NPV ranged from 78.9 to 98.7
Figure 9. Forest plot of sensitivity and specificity: 50 g OGCT by WHO criteria
OGCT = oral glucose challenge test; WHO = World Health Organization
32
Table 6. Prevalence and diagnostic test characteristics for 50 g OGCT by WHO diagnostic criteria
Diagnostic
Test
≥140 mg/dL
OGCT
Author, Year
Country
N*
Screening
Practice**
van Leeuwen,
Netherlands 1,301 Universal
200762
Siribaddana,
Sri Lanka
721
Universal
70
1998
Deerochanawong,
Thailand
709
Universal
73
1996
Prevalence
(%)
PPV
(95% CI)
NPV
(95% CI)
Accuracy
(%)
3.7
20 (14-26) 99 (98-99)
88
6.5
18 (13-23) 99 (97-99)
73
15.7
58 (47-68) 90 (87-92)
86
≥130 mg/dL
Tan, 2007157
Malaysia
521
Universal
34.6
39 (35-41) 86 (78-91)
48
OGCT
CI = confidence interval; NPV = negative predictive value; OGCT = oral glucose challenge test; PPV = positive predictive value;
WHO = World Health Organization
*Number of women in the analysis.
**As reported in the methods of each study; all studies are 2-step screening and diagnosis. Fasting Plasma Glucose Screening and
GDM Diagnosis
This section includes studies that examined FPG as a screening test. A diagnosis of GDM
was confirmed using CC or ADA (2000-2010), WHO, NDDG, and CDA 75 g OGTT criteria.
Fasting Plasma Glucose and CC/ADA (2000-2010) Criteria
Description of Included Studies
Seven studies provided data on FPG at various thresholds as an alternative screening test to
glucola-based screening with a diagnosis of GDM using CC and ADA (2000-2010) criteria
(Appendix D).65,75,99,108,112,126,127 Three studies used a universal screening practice112 108,127 and
the remaining studies used a selective, risk-based screening practice.65,75,99,126 All but one study75
performed the OGTT on all women regardless of OGCT value.
Studies took place in the United States,126,127 France,65,108 Iran,75 and the United Arab
Emirates.99,112 The number of patients enrolled ranged from 123 to 11,545. Mean maternal age
was reported in four studies and ranged from 27.8 to 32.8 years. Mean BMI was reported in three
studies and ranged from 22.5 to 29.6. Most studies tested women after 24 weeks’ gestation; one
study tested women at 23 weeks.126
Results
The studies provided data to estimate the test characteristics of FPG at four common
thresholds: ≥85 mg/dL (4.7 mmol/L), ≥90 mg/dL (5.0 mmol/L), ≥92 mg/dL (5.1 mmol/L), and
≥95 mg/dL (5.3 mmol/L). Figure 10 presents the sensitivities and specificities for the individual
studies. The joint estimates of sensitivity and specificity, respectively for the different FPG
threshold values are:
• ≥85 mg/dL: 87 percent (95% CI, 81 to 91) and 52 percent (95% CI, 50 to 55)
• ≥90 mg/dL: 77 percent (95% CI, 66 to 85) and 76 percent (95% CI, 75 to77)
• ≥92 mg/dL: 76 percent (95% CI, 55 to 91) and 92 percent (95% CI, 86 to 96) (median)
• ≥95 mg/dL: 54 percent (95% CI, 32 to 74) and 93 percent (95% CI, 90 to 96)
The prevalence of GDM ranged from 1.4 to 33.3 (median = 6.2) (Table 7). The PPV ranged
from 12.0 to 45.8; the NPV ranged from 83.3 to 100 (Table 7).
33
Figure 10. Forest plot of sensitivity and specificity: fasting plasma glucose by CC/ADA (2000–
2010) criteria
ADA = American Diabetes Association; CC = Carpenter-Coustan; OGCT = oral glucose challenge test
34
Table 7. Prevalence and diagnostic test characteristics for fasting plasma glucose by CC/ADA
(2000–2010) diagnostic criteria
FPG by
CC/ADA
FPG (≥85
mg/dL)
Author, Year
Country
Agarwal,
99
2000
UAE
FPG (≥90
mg/dL)
FPG (≥92
mg/dL)
Agarwal,
112
2006
Chastang,
65
2003
Sacks,
126
2003
Chevalier,
108
2011
75
Kashi, 2007
Kauffman,
127
2006
Agarwal,
99
2000
FPG (≥95
mg/dL)
1,276 (RF)
398
(+OGCT)
Screening Prevalence
PPV
NPV
Accuracy
Practice**
(%)
(95% CI)
(95% CI)
(%)
Selective
31.8
47 (40-53) 93 (87-96)
64
Selective
31.0
46 (42-49) 91 (88-93)
64
4,609
Universal
13.3
23 (21-24) 97 (96-98)
58
200
Selective
34.5
59 (49-68) 90 (83-94)
75
4,507
Universal
7.2
10 (9-11)
96 (95-97)
50
1,276 (RF)
398
(+GCT)
Selective
31.8
59 (51-66) 91 (86-94)
76
UAE
Selective
30.9
59 (54-63) 91 (88-92)
77
UAE
4,609
Universal
13.3
35 (32-37) 97 (96-97)
77
France
354
High risk
19.5
43 (34-52) 93 (89-95)
76
U.S.
4,507
Universal
6.7
14 (12-16) 96 (95-96)
75
France
11,454
Universal
23.9
63 (55-71) 81 (78-83)
79
Iran
200
Selective
34.7
85 (74-91) 90 (83-94)
88
U.S.
123
Universal
20.3
66 (47-80) 94 (87-97)
87
Selective
31.8
80 (72-86) 91 (86-93)
87
UAE
1,276 (>1
RF)
398
(+OGCT
Selective
26.9
81 (75-85) 89 (87-90)
87
Agarwal,
UAE
112
2006
75
Kashi ,2007
Iran
Sacks,
U.S.
126
2003
Agarwal,
99
2000
N*
Agarwal,
UAE
4,609
Universal
13.2
51 (48-54) 95 (94-96)
87
112
2006
75
Kashi , 2007 Iran
200
Selective
23.9
73 (63-81) 80 (77-82)
79
Sacks,
U.S.
4,507
Universal
6.7
23 (19-27) 95 (94-96)
88
126
2003
ADA = American Diabetes Association; CC = Carpenter-Coustan; CI = confidence interval; FPG = fasting plasma glucose;
NPV = negative predictive value; OGCT = oral glucose challenge test; PPV = positive predictive value; RF = risk factor
screening; UAE = United Arab Emirates
*Number of women in the analysis.
**As reported in the methods of each study.
Fasting Plasma Glucose and Other Diagnostic Criteria
Description of Included Studies
Two studies used the WHO criteria to confirm a diagnosis of GDM,111,120 one used the
NDDG criteria,127 and one each used the criteria from the national organizations from Canada105
and Japan.101 Different FPG thresholds were used: Maegawa et al.101 and Wijeyaratne et al.111
used ≥ 85 mg/dL, Kauffman et al.127 used ≥ 92 mg/dL, and Reichelt et al.120 used ≥ 89 mg/dL.
Results
Table 8 summarizes the prevalence and test characteristics of the studies.
35
Table 8. Prevalence and diagnostic test characteristics for fasting plasma glucose by NDDG-WHO
and other diagnostic criteria
Author, Year,
PrevaSn (%)
Sp (%)
PPV
NPV
Accuracy
N*
Country
lence (%) (95% CI)
(95% CI)
(95% CI)
(95% CI)
(%)
Reichelt,1998,
4,977
0.3
88 (62-98) 78 (77-79) 1.3 (0.8-2.1) 100
78
120
Brazil
WHO
Wjieyaratne,
criteria
853
16.9
92 (87-96) 71 (68-75) 40 (35-45)
98 (96-99)
75
2006, Sri
111
Lanka**
NDDG
Kauffman123
13.0
81 (54-96) 88 (80-93) 50 (32-68)
97 (92-99)
87
127
criteria
2006, U.S.
749
Maegawa,
st
Other
101 (1 Tri)
1.9
71 (68-79) 83 (78-87) 7 (4-13)
99 (98-100)
82
2003, Japan
nd
(2 Tri)
diagnostic
77 (72-80) 91 (86-94) 20 (13-30)
2.9
99 (98-100)
90
criteria
Rey, 2004,
122
17.2
90 (70-99) 46 (36-56) 22 (14-31)
94 (82- 98)
42
105
Canada*
CI = confidence interval; NDDG = National Diabetes Data Group; NPV = negative predictive value; PPV = positive predictive
value; Sn = sensitivity; Sp = specificity; Tri = trimester; WHO = World Health Organization
*Number of women in the analysis.
** Selective screening practice.
Criteria
Risk Factor-Based Screening and GDM Diagnosis
Description of Included Studies
Eight studies presented data on risk factor-based screening (Appendix
D).63,99,111,114,115,119,151,160 One study was conducted in North America,160 four in
Europe,115,119,151,162 two in the Middle East,114 111 and one in South America.63 The number of
patients enrolled ranged from 532 to 4,918.
Results
Figure 11 presents the sensitivities and specificities for the individual studies. The results
were not pooled because different diagnostic criteria were used across the studies (Table 9). The
prevalence of GDM ranged from 1.7 to 16.9 (Table 9). The PPV ranged from 5 to 20; the NPV
ranged from 94 to 99 (Table 9).
Figure 11. Forest plot of sensitivity and specificity: risk factor screening by different diagnostic
criteria (CC/ADA, NDDG, WHO)
ADA = American Diabetes Association; CC = Carpenter-Coustan; NDDG = National Diabetes Data Group; WHO = World
Health Organization
*author-defined threshold values
36
Table 9. Prevalence and diagnostic test characteristics for risk factor screening by different
diagnostic criteria
PPV
NPV Accuracy
(95% CI) (95% CI)
(%)
99 (9663
Ayach, 2006
Brazil
341
Universal
≥1
3.8
6 (3-10)
49
100)
CC/ADA (20002010)
98 (96114
Hill, 2005
India
830
Universal
≥1
6.2
10 (8-14)
52
99)
Trihospital,
99 (98NDDG
Canada
3,131 Universal
≥2
4.6
19 (15-24)
83
160
1997
99)
Ostlund,
99 (99Sweden
4,918 Universal
≥1
1.7
5 (4-7)
84
119
2003
100)
99 (98115
WHO
Jensen, 2003
Denmark 5,235 Universal
≥1
2.4
5 (4-6)
65
100)
94 (89Wijeyaratne,
Sri Lanka 853
Universal
≥1
16.9
20 (17-23)
34
111
2006
97)
99 (98Author-defined Poyhonen-Alho,
Finland
532
Universal
≥1
3.6
12 (8-19)
79
151
criteria
2005
100)
ADA = American Diabetes Association; CC = Carpenter-Coustan; CI = confidence interval; NDDG = National Diabetes Data
Group; NPV = negative predictive value; PPV = positive predictive value; RF = risk factor; WHO = World Health Organization
*Number of women in the analysis.
**As reported in the methods of each study.
Criteria
Author, Year
Country
N*
Screening
Prevalence
# RF
Practice**
(%)
Other Screening Tests
Other studies examined point of care testing with a glucometer to measure capillary blood
glucose,110,111,116,117,128 or other markers such as fasting plasma insulin,127,139 serum
fructosamine,74,109 glycated hemoglobin (HbA1c),74,113 adiponectin levels,140 and glycosuria.125
The results are summarized in Table 10.
37
Table 10. Prevalence and characteristics of other screening tests by GDM diagnostic criteria
Screening Test
HbA1c
Author, Year
Country
74
Uncu, 1995, Turkey
Agarwal, 2005,
113
UAE
100
Agarwal 2001, UAE
107
Rajput, 2011, India
Serum
fructosamine
Fasting plasma
insulin
Agarwal, 2011,
109
UAE
74
Uncu, 1995, Turkey
100
Agarwal 2001, UAE
Kauffman, 2006,
127
U.S.
139
Yachi, 2007, Japan
Author defined =
(fructosamlne/
Perea-Carrasco,
66
total protein) 2002, Spain
(glucose/100)
Weerakiet ,2006,
Adiponectin
140
Thailand
Agarwal, 2008,
110
UAE
Capillary blood
128
Balaji 2012, India
glucose
Wijeyaratne, 2006,
111
Sri Lanka
42
Index Test
Threshold
7.2%
Reference
Standard
CC
442
7.5%
430
Prevalence
(%)
33.3
Sn (%)
(95% CI)
64 (35-87)
Sp (%)
(95% CI)
64 (44-81)
PPV
(95% CI)
47 (27-68)
NPV
(95% CI)
78 (59-87)
ADA (75 g)
19.0
82 (72-90)
21 (17-26)
20 (16-24)
83 (75-90)
33
5.0%
5.5%
5.3%
CC
ADA
IADPSG
26.8
7.1
23.7
92 (86-96)
86 (72-95)
12 (7-18)
28 (23-33)
61 (57-65)
97 (95-98)
32 (27-37)
15 (11-19)
57 (39-73)
91 (83-95)
98 (96-99)
78 (74-82)
45
63
77
849
≥237 µmol/L
ADA (75 g)
13.3
86 (78-92)
23 (20-27)
15 (12-18)
92 (87-95)
32
42
430
≥2.85 mmol/L
≥210 µmol/L
CC
CC
33.3
26.7
71 (42-92)
92 (86-96)
46 (28-66)
23 (18-28)
40 (23-59)
31 (26-36)
77 (55-86)
89 (81-94)
55
42
123
≥93 µmol/L
NDDG
13.0
56.0 (35-76) 71 (61-80)
33 (21-48)
86 (78-92)
68
509
≥3.66 mmol/L
JSOG (10 wk)
2.0
48 (43-53)
72 (63-80)
86 (80-90)
29 (24-36)
53
578
≥27.2
IWC, 3
7.0
98 (90-100) 89 (86-91)
44 (35-53)
100 (99-100)
90
359
≥10 µg/mL
ADA
16.7
92 (82-97)
31 (26 to
36)
18 (14-23)
96 (91-98)
40
ADA (FPG)
11.2
84 (78-89)
75 (73-77)
30 (26-34)
98 (96-98)
76
N*
607
1,662 ≥88 mg/dL
rd
Accuracy (%)
819
≥140 mg/dL
WHO
10.5
80 (70-88)
98 (97-99)
86 (77-92)
98 (96-99)
97
853
≥130 mg/dL
WHO
16.3
63 (54-70)
37 (34-41)
17 (14-20)
83 (79-87)
42
50 g carb
ADA
8.6
83 (52-98) 86 (79-91) 36 (20-5)
98 (94-100)
breakfast
50 g (28) jelly
Glucose source Lamar, 1999, U.S.69
136
NDDG
3.7
40 (5-85)
85 (78-91) 9 (3-28)
97 (93-99)
beans
121
Rust,1998, U.S.
448 100 g carb meal ADA (20 wk)
3.6
25 (7-52)
98 (96-99) 40 (17-69) 96 (93-98)
ADA = American Diabetes Association; carb = carbohydrate; CC = Carpenter-Coustan; CI = confidence interval; FPG = fasting plasma glucose; GDM = gestational diabetes
mellitus; HbA1c = glycated hemoglobin; IADPSG = International Association of Diabetes in Pregnancy Study Groups; IWC = International Workshop Conference; JSOG = Japan
Society of Obstetrics and Gynecology; NDDG = National Diabetes Data Group; NPV = negative predictive value; PPV = positive predictive value; Sn = sensitivity; Sp =
specificity; UAE = United Arab Emirates; WHO = World Health Organization
*Number of women in the analysis
Eslamian, 2008, Iran
71
64
138
38
86
83
94
Comparison of Early and Late Screening Tests
One study (n = 749) conducted in Japan provided data on screening for GDM in the first and
second trimesters.101 The authors used three different screening tests: FPG, HbA1c, and a casual
50 g, 1-hour OGCT. GDM was confirmed with Japan Society of Obstetrics and Gynecology
criteria (75 g, 2-hour) 2 to 4 weeks after screening. Prevalence of GDM using a universal
screening practice was 1.9 percent in the first trimester and 2.9 percent in the second trimester.
Table 11 presents a summary of the test characteristics by screening test and time point. These
results should be interpreted cautiously as the women diagnosed with GDM in the first trimester
had pre-pregnancy body weight and BMI that were significantly higher than for women who did
not have GDM.
Table 11. Prevalence and characteristics of various screening tests for screening in the first and
second trimesters (Maegawa study)
Screening Test
FPG (85 mg/dL)
50 g OGCT (threshold
130 mg/dL)
Prevalence
(%)
Sn (%)
First trimester
1.9
71.4
83.0
7.4
99.2
Second trimester
2.9
77.0
90.7
20.0
99.3
First trimester
1.9
92.9
77.0
7.1
99.8
2.9
1.9
100.0
71.4
85.4
70.8
17.2
4.4
100
99.2
2.9
36.4
72.9
3.9
97.4
1.9
28.6
100
100
98.7
Trimester
Second trimester
HbA1c (threshold 4.8%; First trimester
83.5% ULN)
Second trimester
HbA1c (threshold 5.8%)
First trimester
Sp (%) PPV (%)
NPV (%)
Second trimester
2.9
13.6
99.9
75
97.4
FPG = fasting plasma glucose; HbA1c = glycated hemoglobin; NPV = negative predictive value; OGCT = oral glucose challenge
test; PPV = positive predictive value; Sn = sensitivity; Sp = specificity; ULN = upper limit of normal
Comparison of Different Diagnostic Criteria
Seven studies provided data on the comparability of two diagnostic tests in the same group of
women. The diagnostic criteria were: 75 g, 2-hour versus 100 g, 3-hour criteria; IADPSG versus
the two-step Australasian Diabetes in Pregnancy Society (ADIPS) criteria; FPG versus ADA 100
g, 3-hour criteria; and IADPSG FPG ≥92 mg/dL versus WHO 75 g criteria.
Four studies compared 75 g, 2-hour criteria with 100 g, 3-hour criteria as the reference
standard; however, different populations were assessed (Figure 12). The study by Brustman (n =
32) was conducted in the United States and compared the results of a 75 g, 3 hour OGTT with a
100 g, 3 hour OGTT.143 Prevalence of GDM was 50 percent with NDDG criteria. The sensitivity
was 29 percent (95% CI, 8 to 58) and the specificity was 89 percent (95% CI, 65 to 99); PPV and
NPV were 100 (95% CI, 69 to 100) and 62 (95% CI, 43 to 72), respectively.
The study by Deerochanawong was conducted in Thailand (n = 709).73 The prevalence of
GDM was 1.4 percent with NDDG criteria and with WHO criteria it was 15.7 percent.
Sensitivity was 100 percent (95% CI, 69 to 100) and specificity was 90 percent (95% CI, 92 to
96). PPV and NPV were 12 (95% CI, 7 to 21) and 100 (95% CI, 99 to100), respectively.
The study by Soonthornpun was also conducted in Thailand (n = 42).118 The prevalence of
GDM using the CC criteria was 21 percent. Sensitivity was 33 percent (95% CI, 7 to 70) and
specificity was 100 percent (95% CI, 89 to 100). PPV and NPV were 100 (95% CI, 53 to 100)
and 85 (95% CI, 71 to 92), respectively.
The fourth study by Mello was conducted in Italy and assessed diagnosis of GDM in women
during early pregnancy (16 to 21 weeks) (n = 227) and late pregnancy (26 to 31 weeks) (n =
39
484).153 For the early pregnancy group, the prevalence using CC criteria was 18 percent.
Sensitivity was 27 percent (95% CI, 14 to 43) and specificity was 98 percent (95% CI, 95 to 99).
PPV and NPV were 73 (95% CI, 48 to 89) and 86 (95% CI, 81 to 90), respectively. For the late
pregnancy group the prevalence of GDM was 12 percent. Sensitivity was 18 percent (95% CI, 10
to 30) and specificity was 96 percent (95% CI, 94 to 98). PPV and NPV were 42 (95% CI, 25 to
61) and 89 (95% CI, 86 to 92), respectively.
Figure 12. Forest plot of sensitivity and specificity: 75 g OGTT by 100 g OGTT
OGTT = oral glucose tolerance test
An Australian study (n = 1,275) compared the diagnosis of GDM using IADPSG criteria
with the ADIPS criteria as the reference standard.124 GDM prevalence was 13.0 percent with
IADPSG criteria compared with 9.6 percent with ADIPS. The sensitivity of IADPSG was 82
percent (95% CI, 74 to 88) and specificity was 94 percent (95% CI, 93 to 96); the PPV and NPV
were 61 percent (95% CI, 53 to 68) and 98 (95% CI, 97 to 99), respectively.
Two studies assessed FPG as a diagnostic test but used different reference standards. A
Brazilian study (n = 341) compared FPG with the ADA 100 g, 3-hour criteria.63 The prevalence
of GDM was 3.8 percent using ADA (2000-2010) 100 g criteria. The sensitivity was 84 percent
(95% CI, 55 to 98) and specificity was 47 percent (95% CI, 42 to 53); PPV and NPV were 6
(95% CI, 3 to10) and 99 (95% CI, 56 to 100), respectively.
The second study, conducted in India (n = 1,463), compared IADPSG FPG criteria with the
WHO 75 g criteria.107 The prevalence of GDM was 13.4 percent with WHO criteria and 3.2
percent with FPG (≥95 mg/dL). The sensitivity of FPG as a diagnostic test was 29 percent (95%
CI, 29 to 36) and specificity was 89 percent (95% CI, 88 to 91); PPV and NPV were 76 (95% CI,
55 to 89) and 79 (95% CI, 58 to 87), respectively.
Key Question 2. What is the direct evidence on the benefits and harms of
screening women for GDM to reduce maternal, fetal, and infant morbidity
and mortality?
Description of Included Studies
Two studies met the inclusion criteria for Key Question 2.130,131 Both studies compared
outcomes for women who underwent screening or diagnostic testing for GDM with women who
were not screened or tested. The studies are described in Appendix D. The studies were
published in 2004130 and 1996.131 The methods and outcomes differed between the studies,
therefore no results were pooled.
40
Methodological Quality of Included Studies
The studies were of high and moderate methodological quality with 7 and 6 of a maximum of
9 points, respectively.130,131 The studies scored well for selection of the non-exposed cohort
(same as exposed cohort), ascertainment of exposure and outcome, and adequacy of followup in
terms of duration and attrition. Neither study controlled for potential confounding variables.
Solomon et al., included a select population (i.e., nurses participating in a longitudinal study) that
may not be representative of the general target population of this review.
Key Points
Only two retrospective cohort studies were relevant to Key Question 2. There were no RCTs
available to answer questions about screening. Based on the small number of studies and sample
sizes, the impact of screening women for GDM on health outcomes is inconclusive.
Detailed Synthesis
One retrospective cohort study examined 1,000 women receiving antenatal care and
delivering at a single center in Thailand between October 2001 and December 2002.130 Women
who presented with specific risk factors underwent screening with OGCT (n = 411), and
subsequent OGTT if positive on the OGCT (n = 164). Among those screened, 29 cases of GDM
were identified (7 percent of the screened group; 3 percent of the total population). Among those
who did not undergo screening, 40 women at high risk for GDM were missed (4 percent) and
there were two cases of pregestational DM (0.2 percent). High risk was determined based on a
list of risk factors, the most commonly observed were age ≥ 30 years (53 percent of the 40
patients) and family history of type 2 diabetes mellitus (43 percent of the 40 patients). Appendix
D lists the obstetric complications that were reported in decreasing frequency. Overall there were
significantly more complications in the screened group (64/411 versus 63/589). The only
individual obstetric complication that was different between groups was pregnancy-induced
hypertension with significantly more cases in the screened group. The screened group was
significantly older and had a higher average BMI than the group not screened. The pregnancy
outcomes are listed in Appendix D. The only significant difference was in the incidence of
cesarean deliveries which was greater in the screened group. The authors concluded that
selective OGCT screening was highly effective in detecting GDM; however, the impact on
outcomes was inconclusive due to small numbers. No information was provided on how women
who screened positive were treated.
The second study involved a survey of a subset of participants in a large prospective cohort
study involving 116,678 nurses age 25-42 years (the Nurses’ Health Study II).131 Surveys were
sent to 422 women who reported a first diagnosis of GDM between 1989 and 1991, as well as a
sample of 100 women who reported a pregnancy but no diagnosis of GDM. The intent of the
study was to determine the frequency of screening for GDM and the extent to which diagnosis is
based on NDDG criteria. Only one outcome was reported that was relevant to this Key Question:
the incidence of macrosomia (infant weight > = 4.3 kg) was the same in the screened and
unscreened groups (7 percent each group). These results pertained to 93 eligible women who
reported a pregnancy and no diagnosis of GDM, 77 of whom reported having a 1-h 50-g OGCT.
No information was provided on how women who screened positive were treated. No relevant
outcomes were reported for the group of women who reported a pregnancy and first diagnosis of
GDM.
41
Key Question 3. In the absence of treatment, how do health outcomes of
mothers who meet various criteria for GDM and their offspring compare to
those who do not?
Description of Included Studies
Thirty-eight studies met the inclusion criteria for Key Question 3.3,54,67,78-94,102,103,106,132137,142,145-147,149,150,152,154,155
The studies are described in Appendix D. Studies provided data for
untreated women who met criteria for GDM, showed differing levels of glucose tolerance, or had
no GDM. Most included studies were prospective or retrospective cohort studies published
between 1995 and 2011 (median year 2004). Two studies were long-term followup studies of
RCTs; however, only data from the untreated patients were included in the results for this Key
Question.54,142 These studies had associated publications providing more detailed break-down of
groups and outcomes.160,163 Fourteen studies were conducted in the U.S.,54,78,81,8891,132,135,136,146,150,152
10 in Europe,80,86,87,93,102,106,133,145,149,154 2 in Canada,83,142 2 in Australia,3,85
and 11 from other countries67,79,82,84,92,94,103,134,137,147,155 (including Japan, Saudi Arabia, Turkey,
Iran, China, and Taiwan). Populations analyzed in North American studies involved diverse
ethnicities representative of the respective populations; studies from Europe or elsewhere most
often included women of ethnic descent from the country of study origin. In one case, women
analyzed were at risk for GDM;149 this study has been noted as potentially unrepresentative of all
women eligible for screening.
We grouped studies according to the diagnostic criteria used; these included CC, NDDG,
WHO, and IADPSG. CC values were endorsed by the ADA 2000-2010 as well as the 4th and 5th
IWC on Gestational Diabetes. Most studies employing NDDG criteria provided comparison
groups of women diagnosed with CC criteria. In most cases, the NDDG GDM group received
treatment for GDM as it is commonly considered unethical in North America to not treat these
women; therefore, these groups were not included in the results for this Key Question. One study
compared unrecognized cases of NDDG GDM with a patient group with no GDM; the
unrecognized cases were sixteen women diagnosed postpartum and therefore did not receive any
treatment.152 CC groups were included; therefore, data from studies employing NDDG criteria
with CC comparison groups, CC criteria, ADA, or 4th – 5th IWC criteria were included in the
results. Table 1 provides an overview of these criteria.
Seventeen studies employed NDDG criteria (with treated groups excluded from this
analysis), CC criteria, ADA, or 4th-5th IWC criteria with comparable groups. Groups included
GDM diagnosed by CC criteria, no GDM by any criteria (normal), impaired glucose tolerance
(IGT) defined as one abnormal glucose value (OAV), and false positive (positive OGCT,
negative OGTT). Two studies had unique group selections and are described in the text below.
Six studies utilized NDDG criteria exclusively. Four of these presented consistent groups for
analysis: normal (no GDM by any criteria) and false positive. One study retrospectively
identified women with unrecognized GDM by NDDG criteria and compared this group with
woman with normal glucose tolerance.
Eight studies presented data according to WHO criteria, four of which provided comparable
groups. WHO criteria proved a significant challenge due to variability by year, studies providing
insufficient groupings for comparison, and treatment of most IGT or OAV groups. One of the
two included studies provided data for women diagnosed with IGT at 8.0-8.9 mmol/L (untreated)
and the other provided a similar IGT diagnosis at 7.8-8.9 mmol/L, both at two hours post 75 g
load. Studies were pooled for analysis as they were deemed to be sufficiently similar. One study
42
compared WHO GDM (untreated) with no GDM, and was included in the analysis for
macrosomia.84 Three studies comparing differing levels of WHO criteria were excluded from
pooled analysis because they did not have comparable groups with other included
studies.134,137,147
Three studies utilized IADPSG criteria for diagnosis and provided comparable groups for
pooled analysis.78,79,93
Methodological Quality of Included Studies
The methodological quality of the included studies is described in Appendix C3. Quality was
analyzed using the Newcastle-Ottawa Scale (NOS) with a possible total of 9 stars. The median
quality score was 9 stars, with two studies receiving a score of 6/9, nine studies a score of 7/9,
seven studies a score of 8/9, and twenty a score of 9/9. Studies receiving lower scores on the
NOS most often did not control for potential confounding (e.g., due to BMI, age, race), and/or
had an important proportion of patients lost to followup. Overall, the majority of studies were
considered good quality (36 of 38, 95 percent).
Key Points
•
•
Thirty-eight studies provided data for this question that sought to examine health
outcomes for women who meet various criteria for GDM and do not receive treatment.
The majority of data came from cohort studies or the untreated groups from randomized
trials.
A wide variety of diagnostic criteria and thresholds were compared across the studies.
The most common groups reported and compared were GDM diagnosed by CC criteria,
no GDM by any criteria (normal), impaired glucose tolerance defined as OAV, and false
positive (positive OGCT, negative OGTT). The following criteria were used: CC (19
studies), NDDG (6 studies), WHO (8 studies), and IADPSG (3 studies).
Maternal Outcomes
•
•
•
A methodologically strong study showed a continuous positive relationship between
increasing glucose levels and the incidence of primary cesarean section. This study also
found significantly fewer cases of preeclampsia and cesarean section among women
without GDM compared with those meeting IADPSG criteria.
For preeclampsia, significant differences were found for CC versus patients with no
GDM (3 studies) with fewer cases among the patients with no GDM, and for CC GDM
versus false-positive groups (2 studies) with fewer cases among the false positives. The
strength of evidence for these comparisons was low. No differences were found for
NDDG false positive versus no GDM (2 studies), NDDG 1 abnormal OGTT versus no
GDM (1 study), and IGT WHO versus no GDM (3 studies); the strength of evidence for
these findings was insufficient.
For maternal hypertension, significant differences were found for eight of 16
comparisons; five of these comparisons were based on single studies. Patient groups with
no GDM showed lower incidence of maternal hypertension when compared with CC
GDM, CC false positives, CC 1 abnormal OGTT, IADPSG impaired fasting glucose
(IFG), IADPSG double impaired glucose tolerance (IGT-2), and IADPSG IGT IFG.
Other comparisons showing significant differences were CC GDM versus false positives
43
•
•
•
•
•
(lower incidence for false positives), IADPSG IGT versus IGT IFG (lower incidence for
IGT), and IADPSG IFG versus IGT IFG (lower incidence for IFG).
There were 21 comparisons for cesarean section with nine significant differences. Patient
groups with no GDM showed fewer cesarean sections when compared with CC GDM (9
studies), CC 1 abnormal OGTT (4 studies), CC false positives (5 studies), NDDG false
positives (4 studies), NDDG 1 abnormal OGTT (1 study), and WHO IGT (4 studies).
Four studies compared CC GDM versus false positives and showed lower incidence for
the false positives. Single studies compared IADPSG IFG and IADPSG IGT IFG versus
no GDM, respectively, and both showed fewer cases for the patient groups with no
GDM.
Based on single studies, no differences were observed for maternal birth trauma for CC
GDM versus no GDM , CC GDM versus false positives, NDDG GDM (unrecognized)
versus no GDM.
For maternal weight gain, significant differences were found for three of 12 comparisons:
IADPSG IGT versus no GDM (favored IGT), IADPSG IFG versus no GDM (favored
IFG), IADPSG IGT-2 versus no GDM (favored IGT-2). All comparisons were based on
single studies and strength of evidence was considered insufficient.
For maternal mortality/morbidity, single studies compared CC GDM versus no GDM,
CC 1 abnormal OGTT versus no GDM, IADPSG GDM versus no GDM. No differences
were found except for the latter comparison that showed lower mortality/morbidity for
the patient groups with no GDM.
No studies provided data on long-term maternal outcomes, such as type 2 diabetes
mellitus, obesity and hypertension.
Fetal/Neonatal/Child Outcomes
•
•
•
•
Two methodologically strong studies showed a continuous positive relationship between
increasing glucose levels and the incidence of macrosomia. One of these studies also
showed significantly fewer cases of shoulder dystocia and/or birth injury, clinical
neonatal hypoglycemia, and hyperbilirubinemia among women without GDM compared
with women meeting IADPSG criteria.
The most commonly reported outcome was macrosomia >4,000 g. Eleven comparisons
were made of which six showed a significant difference. Fewer cases were observed
among patient groups with no GDM compared with CC GDM (10 studies), CC 1
abnormal OGTT (7 studies), NDDG GDM (unrecognized) (1 study), NDDG falsepositives (4 studies), and WHO IGT (1 study). Fewer cases were found for women with
false-positive results compared with CC GDM (5 studies). The strength of evidence for
these findings was low to insufficient.
Data for macrosomia >4,500 g were available for four comparisons and showed
significant differences in two cases: patient groups with no GDM had fewer cases
compared with women with CC GDM and with unrecognized NDDG GDM. The strength
of evidence for these findings was low and was insufficient, respectively.
For shoulder dystocia, significant differences were found for 7 of 17 comparisons; all but
1 comparison was based on single studies (insufficient strength of evidence). Patient
groups with no GDM showed lower incidence of shoulder dystocia when compared with
CC GDM (5 studies; low strength of evidence), NDDG GDM (unrecognized), NDDG
false positive, WHO IGT, IADPSG IFG, and IADPSG IGT IFG. The other significant
44
•
•
•
•
•
difference showed lower incidence among the false-positive group compared with CC 1
abnormal OGTT.
For fetal birth trauma/injury, four studies compared CC GDM, NDDG GDM, and WHO
IGT with no GDM. No differences were observed except for NDDG GDM which favored
the patient group with no GDM. Strength of evidence was insufficient for all
comparisons.
Only one difference was found for neonatal hypoglycemia with fewer cases among
patient groups with no GDM compared with those meeting CC criteria. No differences
were found for other comparisons, including CC GDM versus 1 abnormal OGTT (1
study), CC 1 abnormal OGTT versus no GDM (4 studies), NDDG GDM versus no GDM
(1 study), NDDG false positive versus no GDM (1 study), NDDG 1 abnormal OGTT
versus no GDM (1 study), and WHO IGT versus no GDM (3 studies). Strength of
evidence was insufficient for all comparisons.
There were 16 comparisons for hyperbilirubinemia; the majority were based on single
studies. Three comparisons showed significant differences between groups: patient
groups with no GDM had fewer cases compared with CC false positive, IADPSG IGT,
and IADPSG IGT-2, respectively.
No differences were found for fetal morbidity/mortality for any of 8 comparisons which
may be attributable to small numbers of events within some comparisons. Most
comparisons were based on few studies, except for CC GDM versus no GDM which
showed no difference based on 6 studies.
Based on single studies, significant differences were found in prevalence of childhood
obesity for CC GDM versus groups with no GDM (lower prevalence for no GDM) and
CC GDM versus false positives (lower prevalence for false positives). No differences,
based on single studies, were found for CC GDM versus 1 abnormal OGTT, CC false
positive versus no GDM, CC false positive versus 1 abnormal OGTT, or CC 1 abnormal
OGTT versus no GDM. No other studies provided data on long-term outcomes, including
type 2 diabetes mellitus and transgenerational GDM.
Detailed Synthesis
Overview
Detailed results are described by outcome in the sections that follow. We first describe the
maternal outcomes, followed by fetal/neonatal/child outcomes. We present meta-graphs when
two or more studies were pooled. These are displayed after the description of results for each
outcome. A detailed table of results and a table summarizing the strength of evidence are
presented at the end of each of the maternal and fetal/neonatal/child sections (Table 12 and
Table 13; Table 14 and Table 15, respectively). The results reported below are based on
unadjusted data from the relevant studies. We have reported adjusted results, where available
from relevant studies, in Appendix G. In the majority of cases, the adjusted results would not
have changed the pooled estimates or overall conclusions. Six studies met inclusion criteria and
provided relevant outcomes but were not comparable with other studies and are described
here.3,91,134,137,147
In 1995, Sacks et al. published a prospective cohort study of 3,505 unselected pregnant
women; the authors sought to determine glucose threshold distributions for the 2 hr, 75 g OGTT,
and to define the relationship between glucose intolerance values and neonatal macrosomia. The
45
methodological quality of the study was good receiving a score of 8/9 points. Study participants
were not analyzed by groups, rather regression analyses were conducted to identify a threshold
level that predicted greater risk for macrosomia. The study did not identify a specific threshold
for fasting or 1-2 hour levels that could discriminate between women who were more likely to
have infants with macrosomia. Moreover, across all thresholds the ability to predict macrosomia
was relatively consistent.
The HAPO (Hyperglycemia and Adverse Pregnancy Outcomes) study, published in 2008,
examined the effect of less severe hyperglycemia on pregnancy outcomes; therefore, all groups
fell below the common diagnostic thresholds for GDM. The study involved 23,316 pregnant
women from 15 centers in nine countries. The methodological quality was good with a score of
9/9 points. Women were tested employing the 75 g OGTT at 24-32 weeks. Fasting plasma
glucose values were divided into seven categories: ≥100 mg/dL (5.6 mmol/L), 95-99 (5.3-5.5),
90-94 (5.0-5.2), 85-89 (4.8-4.9), and <85. The last category (<85 mg/dL) was further subdivided
into three levels: <75 mg/dL (4.2 mmol/L), 75-59 (4.2-4.4), and 80-84 (4.5-4.7). The study found
a continuous positive association with increasing glucose levels and macrosomia (or birthweight
>90th percentile), primary cesarean section, neonatal hypoglycemia, and cord-blood serum cpeptide >90th percentile. The associations were strongest for macrosomia and blood serum cpeptide levels; moreover, associations for neonatal hypoglycemia were not consistently
significant. In unadjusted analyses, preeclampsia, cesarean delivery, shoulder dystocia and/or
birth injury, clinical neonatal hypoglycemia, and hyperbilirubinemia were statistically
significantly less frequent for women without GDM compared with those with GDM based on
the IADPSG criteria (data from Appendix, Table B available at
care.diabetesjournals.org/cgi/content/full/dc09-1848/DC1). The study did not identify a clear
glucose threshold for increased risk in clinically important outcomes.24
Two studies134,147 conducted in China utilized 1980 WHO criteria on a 2 hr OGTT but did
not provide similar groups for comparison. One retrospective cohort study published in 2003
involving 2,149 women compared six glucose values: <6.0 mmol/L, 6.0-6.9, 7.0-7.9, 8.0-8.9,
9.0-10.9, and ≥11.0.147 The latter 3 groups were treated for GDM; the former were untreated.
There was no significant difference between groups in the incidence of macrosomia (≥4,000 g)
or cesarean deliveries. The methodological quality of the study was good with 8/9 points. The
second study published in 2001 was prospective and involved 487 women. The study compared
a control group, an “at risk” but normal OGTT group, and a treated GDM group.134 There were
no significant differences between groups in preeclampsia or birthweight. There were
significantly more cesarean deliveries in the normal OGTT compared with the control group
although the comparison did not control for age and BMI (women in the normal OGTT group
were older and more obese). The methodological quality was fair scoring 6/9 points.
One study137 conducted in Malaysia used 1999 WHO criteria on a 2 hr OGTT in conjunction
with a 50 g OGCT. As WHO criteria rarely utilize an OGCT, this study did not provide
comparable groups for pooled analysis as they were based upon OGCT test results. The study
found significantly more cases of cesarean delivery, postpartum hemorrhage, and macrosomia
(>4,000 g) among OGCT-positive versus OGCT-negative women.
A study conducted in Turkey between 2003 and 2009 employed CC criteria on a 50 g OGCT
as well as a 3 hr, 100 g OGTT.94 Groups were determined according to abnormal fasting, 1 hr, 2
hr, and 3 hr glucose values, which did not provide comparison to included studies. The study did
not find a significant difference between groups in mean neonatal birthweight. There were
46
significantly more cases of macrosomia (>4,000 g) among women with increased serum glucose
at 2 hours.
Maternal Outcomes
Short Term
A summary of the evidence for short-term maternal outcomes is provided in Table 12. A
summary of the strength of evidence is in Table 13. The sections that follow describe the results
by outcome.
Preeclampsia
Ten studies presented data on preeclampsia (Table 12).81,82,88-90,103,133,149,155,160 Definitions of
preeclampsia were only reported in two of the ten studies, and the definitions differed. Three
studies compared women who met CC criteria for GDM with women who had no GDM and
found a significant difference with fewer cases among the no GDM group (Figure 13).81,89,160
Two studies compared women who met CC criteria for GDM with women who were false
positive and demonstrated a significant difference with fewer cases in the false-positive group
(Figure 14).90,160 The strength of evidence for these two comparisons was low. The following
three comparisons showed no differences between groups: 1 abnormal OGTT by NDDG versus
no GDM (1 study),103 false positive NDDG versus no GDM (2 studies, Figure 15),82,88 and IGT
by WHO criteria versus no GDM (3 studies, Figure 16).133,149,155 The strength of evidence for
these three comparisons was insufficient.
Figure 13. CC GDM versus no GDM: preeclampsia
Study or Subgroup
Cheng, 2009
Naylor, 1996
Pennison, 2001
Experimental
Control
Events
Total Events Total Weight
17
10
9
Total (95% CI)
Risk Ratio
M-H, Random, 95% CI
273
115
43
627 13940
144 2940
10
69
52.5%
30.4%
17.2%
1.38 [0.87, 2.21]
1.78 [0.96, 3.28]
1.44 [0.64, 3.27]
431
16949
100.0%
1.50 [1.07, 2.11]
Total events
36
781
Heterogeneity: Tau² = 0.00; Chi² = 0.41, df = 2 (P = 0.81); I² = 0%
Test for overall effect: Z = 2.37 (P = 0.02)
Risk Ratio
M-H, Random, 95% CI
0.2
0.5
1
2
5
Favors CC criteria Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus, M-H = Mantel-Haenszel
Figure 14. CC GDM versus false positive: preeclampsia
Study or Subgroup
Berggren, 2011
Naylor, 1996
Total (95% CI)
CC criteria
False-positive
Total Weight
Events Total Events
58
10
460
115
575
264
31
Risk Ratio
M-H, Random, 95% CI
3117
580
86.8%
13.2%
1.49 [1.14, 1.94]
1.63 [0.82, 3.22]
3697
100.0%
1.51 [1.17, 1.93]
295
68
Total events
Heterogeneity: Tau² = 0.00; Chi² = 0.06, df = 1 (P = 0.81); I² = 0%
Test for overall effect: Z = 3.23 (P = 0.001)
Risk Ratio
M-H, Random, 95% CI
0.2
0.5
1
2
5
Favors CC criteria Favors False-positive
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus, M-H = Mantel-Haenszel
47
Figure 15. NDDG false positive versus no GDM: preeclampsia
Study or Subgroup
NDDG False-positive
No GDM
Events
Total Events Total Weight
7
10
Biri, 2009
Stamilio, 2004
326
164
490
Total (95% CI)
21
107
Risk Ratio
M-H, Random, 95% CI
1432
1661
35.5%
64.5%
1.46 [0.63, 3.42]
0.95 [0.51, 1.77]
3093
100.0%
1.10 [0.67, 1.83]
128
17
Total events
Heterogeneity: Tau² = 0.00; Chi² = 0.66, df = 1 (P = 0.42); I² = 0%
Test for overall effect: Z = 0.39 (P = 0.70)
Risk Ratio
M-H, Random, 95% CI
0.2
0.5
1
2
5
Favors False-positive Favors No GDM
CI = confidence interval; GDM = gestational diabetes mellitus, NDDG = National Diabetes Data Group; M-H = MantelHaenszel
Figure 16. WHO impaired glucose tolerance versus no GDM: preeclampsia
Study or Subgroup
Jensen, 2003
Nord, 1995
Yang, 2002
IGT by WHO
Events Total
No GDM by WHO
Total Weight
Events
289
223
102
16
13
3
614
Total (95% CI)
158
14
0
Risk Ratio
M-H, Random, 95% CI
2596
391
302
50.3%
42.1%
7.6%
0.91 [0.55, 1.50]
1.63 [0.78, 3.40]
20.59 [1.07, 395.30]
3289
100.0%
1.47 [0.62, 3.52]
172
32
Total events
Heterogeneity: Tau² = 0.33; Chi² = 5.40, df = 2 (P = 0.07); I² = 63%
Test for overall effect: Z = 0.87 (P = 0.38)
Risk Ratio
M-H, Random, 95% CI
0.2
0.5
1
2
5
Favors IGT by WHO Favors No GDM by WHO
CI = confidence interval; GDM = gestational diabetes mellitus, IGT = impaired glucose tolerance; M-H = Mantel-Haenszel;
WHO = World Health Organization
Maternal Hypertension
Nine studies presented data on maternal hypertension (Table 12).78,80,90,92,93,102,106,133,163 Four
studies compared women who met CC criteria for GDM with women without GDM and showed
significantly fewer cases in the no GDM group (Figure 17).92,93,102,163 Two studies comparing
women who met CC criteria for GDM with women who were false positive showed a significant
difference with fewer cases in the false-positive group (Figure 18).90,102 Two studies compared
one abnormal OGTT by CC criteria with no GDM and showed a significant difference with
fewer cases in the group with no GDM (Figure 19).80,106 No differences were found for the
following comparisons: CC false positive versus no GDM (1 study),102 WHO IGT versus no
GDM (1 study),133 and IADPSG GDM versus no GDM (1 study).93 A single study of IADPSG
criteria78 made comparisons across six different groups and found significant differences for:
IADPSG IFG versus no GDM, IADPSG double impaired glucose tolerance (IGT-2) versus no
GDM, IADPSG IGT IFG versus no GDM (all favoring no GDM); IADPSG IGT versus IGT IFG
(favoring IGT); and IADPSG IFG versus IGT IFG (favoring IFG).
Figure 17. CC GDM versus no GDM: maternal hypertension
Study or Subgroup
Chou, 2010
Landon, 2011
Lapolla, 2011
Ricart, 2005
CC criteria
No GDM
Events Total Events Total Weight
10
62
9
10
489
455
112
263
238 10116
31
423
76 1815
108 6350
Risk Ratio
M-H, Random, 95% CI
22.6%
34.1%
21.1%
22.2%
0.87 [0.46, 1.63]
1.86 [1.23, 2.80]
1.92 [0.99, 3.73]
2.24 [1.18, 4.22]
1319
18704 100.0%
Total events
91
453
Heterogeneity: Tau² = 0.07; Chi² = 5.49, df = 3 (P = 0.14); I² = 45%
Test for overall effect: Z = 2.51 (P = 0.01)
1.64 [1.11, 2.42]
Total (95% CI)
Risk Ratio
M-H, Random, 95% CI
0.2
0.5
1
2
5
Favors CC criteria Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus, M-H = Mantel-Haenszel
48
Figure 18. CC GDM versus false positive: maternal hypertension
Study or Subgroup
Berggren, 2011
Ricart, 2005
CC criteria
False-positive
Events Total Events
Total Weight
33
10
460
263
150
42
723
Total (95% CI)
Risk Ratio
M-H, Random, 95% CI
3117
1838
77.6%
22.4%
1.49 [1.04, 2.15]
1.66 [0.85, 3.28]
4955
100.0%
1.53 [1.11, 2.11]
192
Total events
43
Heterogeneity: Tau² = 0.00; Chi² = 0.08, df = 1 (P = 0.78); I² = 0%
Test for overall effect: Z = 2.59 (P = 0.010)
Risk Ratio
M-H, Random, 95% CI
0.01
0.1
1
10
100
Favors CC criteria Favors False-positive
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus, M-H = Mantel-Haenszel
Figure 19. CC 1 Abnormal OGTT versus no GDM: maternal hypertension
Study or Subgroup
Corrado, 2009
Vambergue, 2000
Total (95% CI)
CC 1 Abnormal OGTT
No GDM
Total Events Total Weight
Events
21
14
152
131
283
27
5
Risk Ratio
M-H, Random, 95% CI
76.9%
23.1%
3.19 [1.86, 5.49]
2.31 [0.86, 6.21]
732 100.0%
2.96 [1.84, 4.77]
624
108
32
35
Total events
Heterogeneity: Tau² = 0.00; Chi² = 0.33, df = 1 (P = 0.57); I² = 0%
Test for overall effect: Z = 4.48 (P < 0.00001)
Risk Ratio
M-H, Random, 95% CI
0.01
0.1
1
10
100
Favors 1 Abnormal OGTT Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus, M-H = Mantel-Haenszel ; OGTT =
oral glucose tolerance test
Cesarean Delivery
Twenty-six studies presented data for cesarean delivery (Table 12).67,78,80,81,83,8590,92,93,102,103,132,133,135,145,146,149,150,152,154,155,160
Nine studies compared CC GDM with no GDM and
found a significant difference with fewer cases for the no GDM group (Figure
20).81,86,89,92,93,102,146,150,160 Four studies compared CC GDM with false-positive results and
showed significantly fewer cases in the false-positive group (Figure 21).90,102,150,160 Four studies
compared CC 1 abnormal OGTT versus no GDM and found fewer cases in the group with no
GDM (Figure 22).80,86,106,135 Five studies compared CC false positives with no GDM and found
fewer events among patient groups with no GDM (Figure 23).87,102,145,150,160 One study compared
NDDG with 1 abnormal OGTT with women without GDM and found fewer events for the no
GDM group.103 Four studies comparing NDDG false positives versus no GDM showed a
significant difference with fewer events for the no GDM group (Figure 24).67,88,132,152 Four
studies compared WHO impaired glucose tolerance with no GDM, a significant difference was
found in favor of the no GDM group (Figure 25).133,149,154,155 One study compared IADPSG IFG
versus no GDM, and the same study compared IADPSG IGT IFG versus no GDM with both
showing significant differences with fewer cases in the no GDM group.78 There were no
differences between groups for the remaining comparisons (Table 12; Figure 26).
49
Figure 20. CC GDM versus no GDM: cesarean delivery
Study or Subgroup
Cheng, 2009
Chico, 2005
Chou, 2010
Langer, 2005
Lapolla, 2011
Naylor, 1996
Pennison, 2001
Ricart, 2005
Schwartz, 1999
CC
No GDM
Events Total Events Total Weight
62
122
196
132
49
34
13
59
38
273
422
489
555
112
115
43
263
154
2356 13940
1442 5767
3761 10116
158 1110
564 1815
585 2940
17
69
1219 6350
1110 7207
Risk Ratio
M-H, Random, 95% CI
11.7%
14.7%
16.8%
12.3%
11.7%
9.0%
3.2%
11.3%
9.4%
Total (95% CI)
2426
49314 100.0%
Total events
705
11212
Heterogeneity: Tau² = 0.02; Chi² = 21.49, df = 8 (P = 0.006); I² = 63%
Test for overall effect: Z = 4.54 (P < 0.00001)
Risk Ratio
M-H, Random, 95% CI
1.34 [1.08, 1.68]
1.16 [0.99, 1.35]
1.08 [0.96, 1.20]
1.67 [1.36, 2.06]
1.41 [1.13, 1.76]
1.49 [1.11, 1.99]
1.23 [0.66, 2.27]
1.17 [0.93, 1.47]
1.60 [1.21, 2.12]
1.32 [1.17, 1.48]
0.2
0.5
1
2
5
Favors CC Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus, M-H = Mantel-Haenszel
Figure 21. CC GDM versus false positive: cesarean delivery
Study or Subgroup
Berggren, 2011
Naylor, 1996
Ricart, 2005
Schwartz, 1999
CC
False-positive
Events Total Events
Total Weight
160
34
59
38
Total (95% CI)
460
115
263
154
942
136
393
197
992
Risk Ratio
M-H, Random, 95% CI
3117
580
1838
1066
58.8%
10.7%
18.7%
11.8%
1.15 [1.00, 1.32]
1.26 [0.92, 1.73]
1.05 [0.82, 1.34]
1.34 [0.99, 1.81]
6601
100.0%
1.16 [1.05, 1.29]
Total events
291
1668
Heterogeneity: Tau² = 0.00; Chi² = 1.77, df = 3 (P = 0.62); I² = 0%
Test for overall effect: Z = 2.83 (P = 0.005)
Risk Ratio
M-H, Random, 95% CI
0.2
0.5
1
2
5
Favors CC Favors False-positi
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus, M-H = Mantel-Haenszel
Figure 22. CC, 1 abnormal OGTT versus no GDM: cesarean delivery
Study or Subgroup
Chico, 2005
Corrado, 2009
Rust, 1996
Vambergue, 2000
Total (95% CI)
1 Abnormal OGTT
No GDM
Total Events Total Weight
Events
19
85
14
23
59
152
78
131
420
1442
243
32
11
Risk Ratio
M-H, Random, 95% CI
5767
624
205
108
15.5%
73.1%
6.6%
4.8%
1.29 [0.89, 1.87]
1.44 [1.21, 1.71]
1.15 [0.65, 2.04]
1.72 [0.88, 3.37]
6704
100.0%
1.40 [1.21, 1.63]
1728
141
Total events
Heterogeneity: Tau² = 0.00; Chi² = 1.10, df = 3 (P = 0.78); I² = 0%
Test for overall effect: Z = 4.52 (P < 0.00001)
Risk Ratio
M-H, Random, 95% CI
0.2
0.5
1
2
5
Favors CC IGT Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus, IGT = impaired glucose tolerance; M-H
= Mantel-Haenszel ; OGTT = oral glucose tolerance test
50
Figure 23. CC false positive versus no GDM: cesarean delivery
Study or Subgroup
Bo, 2004
Lapolla, 2007
Naylor, 1996
Ricart, 2005
Schwartz, 1999
False-positive
No GDM
Events
Total Events Total Weight
103
45
136
393
197
315
128
580
1838
1066
28
100
585
1219
1110
3927
Total (95% CI)
Risk Ratio
M-H, Random, 95% CI
91
334
2940
6350
7207
4.0%
5.8%
17.8%
46.9%
25.5%
1.06 [0.75, 1.50]
1.17 [0.88, 1.56]
1.18 [1.00, 1.39]
1.11 [1.01, 1.23]
1.20 [1.05, 1.38]
16922
100.0%
1.15 [1.07, 1.23]
Total events
874
3042
Heterogeneity: Tau² = 0.00; Chi² = 1.05, df = 4 (P = 0.90); I² = 0%
Test for overall effect: Z = 3.91 (P < 0.0001)
Risk Ratio
M-H, Random, 95% CI
0.5 0.7 1 1.5 2
Favors False-positive Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus, M-H = Mantel-Haenszel
Figure 24. NDDG false-positive versus no GDM: cesarean delivery
Study or Subgroup
Ardawi, 2000
Hillier, 2007
Retnakaran, 2008
Stamilio, 2004
False-positive by NDDG
No GDM
Total Events Total Weight
Events
3.9%
529
67
187
24
785 1432 83.2%
326
208
4.3%
74
23
128
44
8.6%
286 1661
164
39
3696
805
Total (95% CI)
100.0%
Risk Ratio
M-H, Random, 95% CI
Risk Ratio
M-H, Random, 95% CI
1.01 [0.66, 1.57]
1.16 [1.06, 1.28]
1.11 [0.73, 1.68]
1.38 [1.03, 1.85]
1.17 [1.08, 1.28]
1161
315
Total events
Heterogeneity: Tau² = 0.00; Chi² = 1.73, df = 3 (P = 0.63); I² = 0%
Test for overall effect: Z = 3.62 (P = 0.0003)
0.2
0.5
1
2
5
Favors False-positive Favors No GDM
CI = confidence interval; GDM = gestational diabetes mellitus, M-H = Mantel-Haenszel; NDDG = National Diabetes Data
Group
Figure 25. WHO impaired glucose tolerance versus no GDM: cesarean delivery
Study or Subgroup
Aberg, 2001
Jensen, 2003
Nord, 1995
Yang, 2002
IGT WHO
No GDM
Events Total Events Total Weight
12
54
38
75
Total (95% CI)
131
289
223
102
249
450
45
199
745
Risk Ratio
M-H, Random, 95% CI
4526
2596
391
302
7.0%
26.4%
12.7%
53.9%
1.67 [0.96, 2.89]
1.08 [0.84, 1.39]
1.48 [0.99, 2.21]
1.12 [0.97, 1.29]
7815
100.0%
1.18 [1.01, 1.37]
Total events
179
943
Heterogeneity: Tau² = 0.01; Chi² = 3.86, df = 3 (P = 0.28); I² = 22%
Test for overall effect: Z = 2.12 (P = 0.03)
Risk Ratio
M-H, Random, 95% CI
0.2
0.5
1
2
5
Favors IGT WHO Favors No GDM
CI = confidence interval; GDM = gestational diabetes mellitus, IGT = impaired glucose tolerance; M-H = Mantel-Haenszel;
WHO = World Health Organization
Figure 26. CC, 1 abnormal OGTT versus false positive: cesarean delivery
Study or Subgroup
Kwik, 2007
Lapolla, 2007
1 Abnormal OGTT
False-positive
Total
Total Events
Events
46
27
156
48
61
45
Risk Ratio
M-H, Random, 95% CI
Risk Ratio
M-H, Random, 95% CI
0.95 [0.69, 1.31]
1.60 [1.14, 2.25]
197
128
0.2
0.5
1
2
5
Favors 1 Abnormal OGTT Favors False-positive
CC = Carpenter-Coustan; CI = confidence interval; M-H = Mantel-Haenszel; OGTT = Oral glucose tolerance test
51
Birth Trauma
Three studies presented data for maternal birth trauma (Table 12).81,90,152 Two studies
employed CC GDM and compared with no GDM and a false-positive group, respectively.81,90 In
both studies birth trauma was defined as third or fourth degree perineal laceration. Neither study
found a significant difference between groups. One study compared unrecognized NDDG GDM
with no GDM and showed no difference in rectal injury between groups.152
Weight Gain
Three studies presented data for maternal weight gain (Table 12).78,135,155 One study
compared 1 abnormal glucose tolerance value by CC criteria with no GDM and found no
difference between groups.135 One study compared impaired glucose tolerance by WHO criteria
with no GDM; no significant difference was found between groups.155 One study compared
varying degrees of glucose intolerance by IADPSG criteria.78 Significantly less weight gain was
found in the IGT, IFG, and IGT-2 groups in comparison with no GDM. No significant
differences were noted between any other IADPSG glucose tolerance groups.
Maternal Morbidity/Mortality
Two studies presented data for maternal mortality or morbidity (Table 12).93,135 One study
compared CC GDM as well as IADPSG GDM with no GDM.93 No significant difference was
found between the CC and no GDM groups, while a significant difference favoring no GDM was
found in comparison with the IADPSG group. One study compared one abnormal glucose value
by CC criteria with no GDM, with no significant difference noted between groups.135
Long Term
No studies provided data on long-term maternal outcomes, such as type 2 diabetes mellitus,
obesity and hypertension.
Table 12. Evidence summary table: maternal outcomes
Outcome
Preeclampsia
Maternal
hypertension
17,380
Effect
Estimate*
1.50 [1.07, 2.11]
0%
No GDM
2
4,272
1.51 [1.17, 1.93]
0%
False positive
2
3,583
1.10 [0.67,1.83]
0%
-
1
699
1.33 [0.48, 3.65]
NA
-
WHO IGT vs. no GDM
3
3,903
1.47 [0.62, 3.52]
CC GDM vs. no GDM
4
20,023
1.64 [1.11, 2.42]
2
5,678
1.53 [1.11, 2.11]
0%
False positive
2
1,015
2.96 [1.84, 4.77]
0%
No GDM
1
8,188
1.35 [0.94, 1.94]
NA
-
1
2,885
0.91 [0.55, 1.50]
NA
-
1
1,927
1.92 [0.99, 3.73]
NA
-
1
7,411
1.32 [0.96, 1.82]
NA
-
Comparison
Studies
CC GDM vs. no GDM
CC GDM vs. false
positive
NDDG false positive vs.
no GDM
NDDG, 1 abnormal
OGTT vs. no GDM
3
CC GDM vs. false
positive
CC 1 abnormal OGTT
vs. no GDM
CC false positive vs. no
GDM
IGT WHO vs. no GDM
IADPSG GDM vs. no
GDM
IADPSG IGT vs. no
GDM
Participants
52
I
2
63
%
45
%
Favors
¶
No GDM
Table 12. Evidence summary table: maternal outcomes (continued)
Outcome
Comparison
Studies
Participants
1
7,906
1
7,103
1
7,351
IADPSG IGT vs. IFG
1
1,277
IADPSG IGT vs. IGT-2
1
474
IADPSG IGT vs. IGT
IFG
1
722
IADPSG IFG vs. IGT-2
1
969
1
1,217
1
414
9
51,740
4
7,593
1
481
4
7,124
5
20,849
2
529
1
80
1
699
4
4,501
4
8,560
1
1,927
1
7,411
1
7,906
1
7,103
1
7,351
1
1,277
IADPSG IFG vs. no
GDM
IADPSG IGT-2 vs. no
GDM
IADPSG IGT IFG vs.
no GDM
Maternal
Hypertension
(continued)
IADPSG IFG vs. IGT
IFG
IADPSG IGT-2 vs. IGT
IFG
CC GDM vs. no GDM
CC GDM vs. false
positive
CC GDM vs. 1
abnormal OGTT
CC 1 abnormal OGTT
vs. No GDM
CC false positive vs.
no GDM
CC 1 abnormal OGTT
vs. false positive
Cesarean
delivery
NDDG GDM
(unrecognized) vs. no
GDM
NDDG, 1 abnormal
OGTT vs. no GDM
NDDG false positive
vs. no GDM
WHO IGT vs. no GDM
IADPSG GDM vs. no
GDM
IADPSG IGT vs. no
GDM
IADPSG IFG vs. no
GDM
IADPSG IGT-2 vs. no
GDM
IADPSG IGT IFG vs.
no GDM
IADPSG IGT vs. IFG
53
Effect
Estimate*
1.46 [1.18,
1.80]
1.90 [1.09,
3.31]
2.03 [1.54,
2.69]
0.91 [0.63,
1.31]
0.69 [0.37,
1.31]
0.65 [0.43,
0.98]
0.77 [0.43,
1.37]
0.72 [0.51,
0.99]
0.93 [0.51,
1.72]
1.34 [1.17,
1.48]
1.16 [1.05,
1.29]
0.90 [0.60,
1.34]
1.40 [1.21,
1.63]
1.15 [1.07,
1.23]
Results not
pooled due to
substantial
heterogeneity.
1.60 [0.58,
4.45]
1.69
[1.04,2.75]
1.17 [1.08,
1.28]
1.18 [1.01,
1.37]
1.92 [0.99,
3.73]
1.11 [0.89,
1.39]
1.28 [1.11,
1.47]
1.58 [0.94,
2.64]
1.32 [1.06,
1.63]
0.87 [0.68,
1.12]
I
2
Favors
NA
No GDM
NA
No GDM
NA
No GDM
NA
-
NA
-
NA
IGT
NA
NA
NA
¶
IFG
-
63%
No GDM
0%
False positive
NA
-
0%
No GDM
0%
No GDM
79%
-
NA
-
NA
No GDM
0%
No GDM
22%
No GDM
NA
-
NA
-
NA
NA
NA
NA
No GDM
No GDM
-
Table 12. Evidence summary table: maternal outcomes (continued)
Outcome
Cesarean
delivery
(continued)
Studies
Participants
IADPSG IGT vs. IGT-2
1
474
IADPSG IGT vs. IGT
IFG
1
722
IADPSG IFG vs. IGT-2
1
969
1
1,217
1
414
1
722
1
969
1
1,217
1
414
1
14,213
1
3,577
1
80
2.00 [0.40,
9.97]
1
283
Not calculated
1
404
1
7,411
1
7,906
1
7,103
1
7,351
IADPSG IGT vs. IFG
1
1,277
IADPSG IGT vs. IGT-2
1
474
IADPSG IGT vs. IGT
IFG
1
722
IADPSG IFG vs. IGT-2
1
969
1
1,217
1
414
IADPSG IFG vs. IGT
IFG
IADPSG IGT-2 vs. IGT
IFG
IADPSG IGT vs. IGT
IFG
IADPSG IFG vs. IGT-2
IADPSG IFG vs. IGT
IFG
IADPSG IGT-2 vs. IGT
IFG
CC GDM vs. no GDM
Maternal birth
trauma
CC GDM vs. false
positive
NDDG GDM
(unrecognized) vs. No
GDM
CC 1 abnormal OGTT
vs. no GDM
WHO IGT vs. no GDM
Maternal weight
gain
Effect
Estimate*
0.77 [0.49,
1.21]
0.85 [0.63,
1.14]
0.88 [0.58,
1.34]
0.97 [0.76,
1.24]
1.10 [0.70,
1.72]
0.85 [0.63,
1.14]
0.88 [0.58,
1.34]
0.97 [0.76,
1.24]
1.10 [0.70,
1.72]
1.26 [0.90,
1.76]
0.80 [0.47,
1.39]
Comparison
IADPSG IGT vs. no
GDM
IADPSG IFG vs. no
GDM
IADPSG IGT-2 vs. no
GDM
IADPSG IGT IFG vs.
no GDM
IADPSG IFG vs. IGT
IFG
IADPSG IGT-2 vs. IGT
IFG
54
0.00 [-1.41,
1.41]
-1.90 [-3.37, ‡
0.43]
-1.20 [ -2.25, ‡
0.15]
-2.60 [-5.12, ‡
0.08]
-1.20 [-2.83,
‡
0.43]
-0.70 [-2.45,
‡
1.05]
0.70 [-2.18,
‡
3.58]
-0.70 [-2.85,
‡
1.45]
1.40 [-1.29,
‡
4.09]
0.00 [-1.88,
‡
1.88]
-1.40 [-4.36,
‡
1.56]
2
Favors
NA
-
NA
-
NA
-
NA
-
NA
-
NA
-
NA
-
NA
-
NA
-
NA
-
NA
-
NA
-
NA
-
NA
-
I
†
NA
IGT
NA
IFG
NA
IGT-2
NA
-
NA
-
NA
-
NA
-
NA
-
NA
-
NA
-
¶
Table 12. Evidence summary table: maternal outcomes (continued)
Effect
2
¶
I
Favors
Estimate*
1.53 [0.97,
CC GDM vs. no GDM
1
1,927
NA
2.42]
Maternal
CC 1 abnormal OGTT
1.01 [0.37,
1
283
NA
mortality/
vs. no GDM
2.74]
morbidity
IADPSG GDM vs. no
1.43 [1.01,
1
1,927
NA
No GDM
GDM
2.04]
CC = Carpenter-Coustan; GDM = gestational diabetes mellitus; IFG = impaired fasting glucose; IGT = impaired glucose
tolerance; IGT-2 = double impaired glucose tolerance; IADPSG = International Association of Diabetes and Pregnancy Study
Groups; NA = not applicable; NDDG = National Diabetes Data Group; OGTT = oral glucose tolerance test; WHO = World
Health Organization
*Effect estimates are risk ratios and 95% confidence intervals, except where indicated.
¶Where the result was statistically significant, we have listed the group that had the better outcome (e.g., lower incidence of
preeclampsia).
†Study did not report variances but did report no significant difference between groups.
‡Effect estimates are mean differences and 95% confidence intervals.
Outcome
Comparison
Studies
Participants
Table 13. Strength of evidence summary table: maternal outcomes
Outcome
Comparison
Studies Risk of Bias Consistency Directness Precision
CC GDM vs. no GDM
3
High
Consistent
Direct
Precise
CC GDM vs. false
2
High
Consistent
Direct
Precise
positive
NDDG false positive vs.
Preeclampsia
2
High
Consistent
Direct
Imprecise
no GDM
NDDG, 1 abnormal
1
High
Unknown
Direct
Imprecise
OGTT vs. no GDM
WHO IGT vs. no GDM
3
High
Consistent
Direct
Imprecise
CC 1 abnormal OGTT
1
High
Unknown
Direct
Unknown
vs. no GDM
WHO IGT vs. no GDM
1
High
Unknown
Direct
Unknown
IADPSG IGT vs. no
1
High
Unknown
Direct
Precise
GDM
IADPSG IFG vs. no
1
High
Unknown
Direct
Precise
GDM
IADPSG IGT-2 vs. no
1
High
Unknown
Direct
Precise
GDM
IADPSG IGT IFG vs.
Maternal weight
1
High
Unknown
Direct
Imprecise
no GDM
gain
IADPSG IGT vs. IFG
1
High
Unknown
Direct
Imprecise
IADPSG IGT vs. IGT-2
1
High
Unknown
Direct
Imprecise
IADPSG IGT vs. IGT
1
High
Unknown
Direct
Imprecise
IFG
IADPSG IFG vs. IGT-2
1
High
Unknown
Direct
Imprecise
IADPSG IFG vs. IGT
1
High
Unknown
Direct
Imprecise
IFG
IADPSG IGT-2 vs.
1
High
Unknown
Direct
Imprecise
IGT IFG
CC = Carpenter-Coustan; GDM = gestational diabetes mellitus; IFG = impaired fasting glucose; IGT = impaired glucose
tolerance; IGT-2 = double impaired glucose tolerance; IADPSG = International Association of Diabetes and Pregnancy Study
Groups; NDDG = National Diabetes Data Group; OGTT = oral glucose tolerance test; SOE = strength of evidence; WHO =
World Health Organization
55
SOE
Low
Low
Insufficient
Insufficient
Insufficient
Insufficient
Insufficient
Insufficient
Insufficient
Insufficient
Insufficient
Insufficient
Insufficient
Insufficient
Insufficient
Insufficient
Insufficient
Fetal/Neonatal/Child Outcomes
Short Term
A summary of the evidence for short and long term fetal, neonatal, and child outcomes is
found in Table 14. The strength of evidence is presented in Table 15. The sections that follow
describe the results by outcome.
Macrosomia (>4,000 g)
Twenty-one studies presented data for macrosomia (over 4,000 g) (Table 14).79,80,84-86,8890,92,93,102,106,132,133,135,136,145,146,150,152,160
There were significantly fewer cases of macrosomia in the
patient groups with no GDM compared with CC GDM (10 studies, Figure
27).86,89,92,93,102,132,136,146,150,160 CC 1 abnormal OGTT (7 studies, Figure 28),80,86,106,132,135,136,145
NDDG GDM (1 study),152 NDDG false positives (4 studies, Figure 29),83,86,88,132 and WHO IGT
(1 study).133 Significantly fewer cases of macrosomia were observed among women with falsepositive results compared with CC GDM (5 studies, Figure 30).90,102,132,150,160 There was no
significant difference in other comparisons involving other CC groups (Figure 31, Figure 32,
Figure 33). One study compared WHO GDM with no GDM; no significant difference was
observed between groups.84 Two studies compared women who met IADPSG criteria for GDM
with a no GDM group; no difference was observed between groups (Figure 34).79,93 The strength
of evidence for this outcome was low to insufficient due to risk of bias (all observational
studies), inconsistency across studies, and/or imprecision in effect estimates (Table 15).
Figure 27. CC GDM versus no GDM: macrosomia (>4,000 g)
Study or Subgroup
Berkus, 1995
Chico, 2005
Chou, 2010
Hillier, 2007
Langer, 2005
Lapolla, 2011
Naylor, 1996
Pennison, 2001
Ricart, 2005
Schwartz, 1999
Total (95% CI)
GDM
No GDM
Events Total Events Total Weight
7.4%
573
76
72
13
288 5767 10.1%
422
22
236 10116 10.0%
489
22
905 7609 11.8%
173
25
87 1110 15.5%
555
93
7.0%
145 1815
112
12
395 2940 14.3%
115
33
2.2%
69
5
43
6
292 6350 10.0%
263
21
692 4190 11.7%
91
22
2335
40539
100.0%
3121
269
Total events
Heterogeneity: Tau² = 0.03; Chi² = 15.55, df = 9 (P = 0.08); I² = 42%
Test for overall effect: Z = 5.38 (P < 0.00001)
Risk Ratio
M-H, Random, 95% CI
Risk Ratio
M-H, Random, 95% CI
1.36 [0.80, 2.32]
1.04 [0.68, 1.59]
1.93 [1.26, 2.96]
1.21 [0.84, 1.75]
2.14 [1.63, 2.81]
1.34 [0.77, 2.34]
2.14 [1.58, 2.89]
1.93 [0.63, 5.93]
1.74 [1.13, 2.66]
1.46 [1.01, 2.12]
1.61 [1.35, 1.92]
0.1 0.2
0.5
1
2
5 10
Favors GDM Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel
56
Figure 28. CC, 1 abnormal OGTT versus no GDM: macrosomia (>4,000 g)
Study or Subgroup
Berkus, 1995
Chico, 2005
Corrado, 2009
Hillier, 2007
Lapolla, 2007
Rust, 1996
Vambergue, 2000
1 Abnormal OGTT
No GDM
Total Events Total Weight
Events
573 20.8%
76
87
18
4.4%
288 5767
59
3
624 17.2%
39
152
19
905 7609 39.0%
288
40
3.3%
334
8
48
3
6.7%
205
18
78
6
8.6%
108
8
131
21
15220
843
Total (95% CI)
Risk Ratio
M-H, Random, 95% CI
100.0%
1342
110
Total events
Heterogeneity: Tau² = 0.02; Chi² = 6.99, df = 6 (P = 0.32); I² = 14%
Test for overall effect: Z = 2.99 (P = 0.003)
Risk Ratio
M-H, Random, 95% CI
1.56 [0.98, 2.48]
1.02 [0.34, 3.08]
2.00 [1.19, 3.36]
1.17 [0.87, 1.57]
2.61 [0.72, 9.50]
0.88 [0.36, 2.13]
2.16 [1.00, 4.69]
1.44 [1.13, 1.82]
0.1 0.2
0.5
1
2
5
10
Favors 1 Abnormal OGTT Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; OGTT = oral
glucose tolerance test
Figure 29. NDDG false positive versus no GDM: macrosomia (>4,000 g)
Study or Subgroup
NDDG False-positive
No GDM
Total Events Total Weight
Events
33
83
6
95
187
326
128
164
15
27
18
14
Chico, 2005
Hillier, 2007
Retnakaran, 2008
Stamilio, 2004
805
Total (95% CI)
Risk Ratio
M-H, Random, 95% CI
529
1432
74
1661
21.6%
42.9%
9.7%
25.8%
1.29 [0.71, 2.31]
1.43 [0.94, 2.17]
1.73 [0.72, 4.18]
1.49 [0.87, 2.56]
3696
100.0%
1.44 [1.10, 1.89]
217
74
Total events
Heterogeneity: Tau² = 0.00; Chi² = 0.33, df = 3 (P = 0.95); I² = 0%
Test for overall effect: Z = 2.61 (P = 0.009)
Risk Ratio
M-H, Random, 95% CI
0.2
0.5
1
2
5
Favors False-positive Favors No GDM
CI = confidence interval; GDM = gestational diabetes mellitus; NDDG = National Diabetes Data Group; M-H = Mantel-Haenszel
Figure 30. CC GDM versus false positive: macrosomia (>4,000 g)
Study or Subgroup
Berggren, 2011
Hillier, 2007
Naylor, 1996
Ricart, 2005
Schwartz, 1999
CC GDM
False-positive
Total Weight
Events Total Events
3117 30.1%
411
460
78
999 17.3%
122
173
25
580 20.0%
80
115
33
1838 15.2%
131
263
21
605 17.4%
119
91
22
7139
1102
Total (95% CI)
100.0%
Risk Ratio
M-H, Random, 95% CI
Risk Ratio
M-H, Random, 95% CI
1.29 [1.03, 1.60]
1.18 [0.79, 1.76]
2.08 [1.46, 2.96]
1.12 [0.72, 1.74]
1.23 [0.83, 1.83]
1.36 [1.10, 1.68]
863
179
Total events
Heterogeneity: Tau² = 0.03; Chi² = 7.33, df = 4 (P = 0.12); I² = 45%
Test for overall effect: Z = 2.82 (P = 0.005)
0.2
0.5
1
2
5
Favors GDM Favors False-positiv
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel
Figure 31. CC GDM versus 1 Abnormal OGTT: macrosomia (>4,000 g)
Study or Subgroup
Berkus, 1995
Chico, 2005
Hillier, 2007
Total (95% CI)
GDM
1 Abnormal OGTT
Total Weight
Events
Events Total
13
22
25
72
422
173
667
18
3
40
87
59
288
Risk Ratio
M-H, Random, 95% CI
31.1%
9.3%
59.7%
0.87 [0.46, 1.66]
1.03 [0.32, 3.32]
1.04 [0.66, 1.65]
434 100.0%
0.98 [0.69, 1.41]
61
60
Total events
Heterogeneity: Tau² = 0.00; Chi² = 0.20, df = 2 (P = 0.91); I² = 0%
Test for overall effect: Z = 0.09 (P = 0.93)
Risk Ratio
M-H, Random, 95% CI
0.2
0.5
1
2
5
Favors GDM Favors 1 Abnormal O
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; OGTT = oral
glucose tolerance test
57
Figure 32. CC false positives versus no GDM: macrosomia (>4,000 g)
Study or Subgroup
Hillier, 2007
Lapolla, 2007
Naylor, 1996
Ricart, 2005
Schwartz, 1999
False-positive
No GDM
Events
Total Events Total Weight
122
8
80
131
2
999
128
580
1838
49
905
8
395
21
12
3594
Total (95% CI)
Risk Ratio
M-H, Random, 95% CI
7609
334
2940
263
112
43.8%
3.8%
35.9%
14.9%
1.7%
1.03 [0.86, 1.23]
2.61 [1.00, 6.81]
1.03 [0.82, 1.28]
0.89 [0.57, 1.39]
0.38 [0.09, 1.64]
11258
100.0%
1.02 [0.85, 1.24]
Total events
343
1341
Heterogeneity: Tau² = 0.01; Chi² = 5.80, df = 4 (P = 0.21); I² = 31%
Test for overall effect: Z = 0.25 (P = 0.80)
Risk Ratio
M-H, Random, 95% CI
0.1 0.2
0.5
1
2
5 10
Favors False-positive Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel
Figure 33. CC, 1 Abnormal OGTT versus False positives: macrosomia (>4,000 g)
Study or Subgroup
Hillier, 2007
Kwik, 2007
Lapolla, 2007
1 Abnormal OGTT
False - positive
Total Weight
Total Events
Events
40
42
3
288
213
48
122
19
8
549
Total (95% CI)
Risk Ratio
M-H, Random, 95% CI
999
197
128
51.7%
37.8%
10.6%
1.14 [0.82, 1.59]
2.04 [1.23, 3.39]
1.00 [0.28, 3.61]
1324
100.0%
1.40 [0.89, 2.20]
149
85
Total events
Heterogeneity: Tau² = 0.07; Chi² = 3.82, df = 2 (P = 0.15); I² = 48%
Test for overall effect: Z = 1.46 (P = 0.14)
Risk Ratio
M-H, Random, 95% CI
0.01
0.1
1
10
100
Favors 1 Anormal OGTT Favors False-positive
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel
Figure 34. IADPSG GDM versus No GDM: macrosomia (>4,000 g)
Study or Subgroup
Lapolla, 2011
Morikawa, 2010
Total (95% CI)
IADPSG GDM
No GDM
Total Events Total Weight
Events
12
1
112
43
155
145
0
Risk Ratio
M-H, Random, 95% CI
1815
160
78.8%
21.2%
1.34 [0.77, 2.34]
10.98 [0.46, 264.81]
1975
100.0%
2.09 [0.39, 11.33]
145
13
Total events
Heterogeneity: Tau² = 0.86; Chi² = 1.63, df = 1 (P = 0.20); I² = 39%
Test for overall effect: Z = 0.86 (P = 0.39)
Risk Ratio
M-H, Random, 95% CI
0.01
0.1
1
10
100
Favors IADPSG GDM Favors No GDM
CI = confidence interval; GDM = gestational diabetes mellitus; IADPSG = International Association of the Diabetes in
Pregnancy Study Groups; M-H = Mantel-Haenszel
Macrosomia (>4,500 g)
Four studies presented data on macrosomia (over 4,500 g) (Table 14).81,150,152,160 Three
studies showed a significant difference favoring the group with no GDM compared with CC
GDM (Figure 35). The strength of evidence for this finding was low. No significant difference
was found for CC GDM compared with false positives (2 studies; Figure 36) and CC false
positives versus groups with no GDM (2 studies; Figure 37). One study compared NDDG GDM
with a no GDM group, and found a significant difference in favor of the no GDM group.152 The
strength of evidence for these three findings was insufficient (Table 15).
58
Figure 35. CC GDM versus no GDM: macrosomia (>4,500 g)
Study or Subgroup
Cheng, 2009
Naylor, 1996
Schwartz, 1999
CC GDM
No GDM
Events Total Events Total Weight
11
7
4
Total (95% CI)
Risk Ratio
M-H, Random, 95% CI
273
115
91
223 13940
56 2940
108 4190
50.7%
30.6%
18.7%
2.52 [1.39, 4.56]
3.20 [1.49, 6.86]
1.71 [0.64, 4.53]
479
21070
100.0%
2.52 [1.65, 3.84]
387
22
Total events
Heterogeneity: Tau² = 0.00; Chi² = 1.00, df = 2 (P = 0.61); I² = 0%
Test for overall effect: Z = 4.29 (P < 0.0001)
Risk Ratio
M-H, Random, 95% CI
0.1 0.2
0.5
1
2
5 10
Favors CC GDM Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel
Figure 36. CC GDM versus false positive: macrosomia (>4,500 g)
Study or Subgroup
Naylor, 1996
Schwartz, 1999
Total (95% CI)
False-positive
CC GDM
Total Weight
Events Total Events
7
4
115
91
206
12
28
Risk Ratio
M-H, Random, 95% CI
580
605
52.2%
47.8%
2.94 [1.18, 7.31]
0.95 [0.34, 2.64]
1185
100.0%
1.71 [0.56, 5.24]
40
11
Total events
Heterogeneity: Tau² = 0.41; Chi² = 2.67, df = 1 (P = 0.10); I² = 63%
Test for overall effect: Z = 0.94 (P = 0.34)
Risk Ratio
M-H, Random, 95% CI
0.1 0.2
0.5
1
2
5 10
Favors CC GDM Favors False-positive
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel
Shoulder Dystocia
Twelve studies presented data on shoulder dystocia (Table 14).54,78,81,85,88-90,92,106,133,146,152
Five studies compared women who met CC criteria for GDM with no GDM and found a
significant difference in favor of the no GDM group (Figure 37); the strength of evidence was
rated low (Table 15).81,89,92,146,163 One study compared CC GDM with a false-positive group, no
significant difference was noted.90 One study compared one abnormal OGTT by CC criteria with
no GDM and no significant difference was found between groups.106 One study compared
women with 1 abnormal OGTT value by CC criteria with a false-positive group with a
significant difference noted in favor of the false-positive group.85 One study compared
unrecognized GDM by NDDG criteria with a no GDM group;152 another study compared a falsepositive group with no GDM.88 Both studies noted a significant difference in favor of the groups
with no GDM. A single study compared IGT by WHO criteria and no GDM; a significant
difference was found in favor of group with no GDM.133 One study compared varying degrees of
glucose intolerance by IADPSG criteria and no GDM;78 significant differences were observed
when no GDM was compared with IFG and IGT and fasting glucose combined. No GDM was
favored in both cases. The remaining groups demonstrated no significant differences (Table 14).
The strength of evidence for all comparisons based on single studies was rated insufficient
(Table 15).
59
Figure 37. CC GDM versus no GDM: shoulder dystocia
Study or Subgroup
Cheng, 2009
Chou, 2010
Landon, 2011
Langer, 2005
Pennison, 2001
CC GDM
No GDM
Events Total Events Total Weight
9
2
18
14
1
273
489
455
555
43
237 13940
11 10116
3
423
7 1110
1
69
Risk Ratio
M-H, Random, 95% CI
48.4%
9.2%
14.1%
25.6%
2.8%
1.94 [1.01, 3.73]
3.76 [0.84, 16.92]
5.58 [1.65, 18.80]
4.00 [1.62, 9.85]
1.60 [0.10, 24.99]
1815
25658 100.0%
Total events
44
259
Heterogeneity: Tau² = 0.00; Chi² = 3.51, df = 4 (P = 0.48); I² = 0%
Test for overall effect: Z = 4.52 (P < 0.00001)
2.86 [1.81, 4.51]
Total (95% CI)
Risk Ratio
M-H, Random, 95% CI
0.02 0.1
1
10
50
Favors CC GDM Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel
Clavicular Fracture
No studies provided comparable data on clavicular fracture. However,
this outcome was often a composite outcome within birth injury or fetal birth trauma.
Brachial Plexus Injury
No studies provided comparable data on brachial plexus injury, also often a composite of
birth injury or fetal birth trauma.
Fetal Birth Trauma or Birth Injury
Four studies presented data for fetal birth trauma or traumatic delivery (Table 14).81,149,152,155
Birth trauma was undefined in two studies,149,155 one comparing WHO IGT with no GDM.
Another defined birth trauma as a composite of brachial plexus injury, facial nerve palsy,
clavicular fracture, skull fracture, and head laceration; this study compared CC GDM and no
GDM.81 No significant difference was observed in any comparison. Brachial plexus injury,
cranial nerve palsy, and clavicular facture were also components of birth trauma in one study.152
This study compared women with unrecognized NDDG GDM and no GDM and showed a
significant difference in favor of the no GDM group. Strength of evidence for all comparisons
was insufficient.
Hypoglycemia
Twelve studies presented data on neonatal hypoglycemia (Table
14).67,80,86,89,103,106,133,135,146,149,152,155 Two studies did not define hypoglycemia,67,125 while all
other studies defined hypoglycemia with varying glucose threshold criteria or by necessity of
intravenous glucose. Three studies compared women meeting CC criteria for GDM with groups
without GDM. Results were not pooled due to substantial heterogeneity across studies (I2=94%)
(Figure 38); however, all three studies individually showed fewer cases of hypoglycemia among
the patient groups with no GDM.86,89,146 The difference in results may be explained in part by the
methods of assessing for neonatal hypoglycemia (e.g., biochemical vs. clinical). Posthoc analysis
showed that the magnitude of association between glucose intolerance and neonatal
hypoglycemia was affected by the definition used (i.e., clinical or biochemical). Many of the
observational studies included did not routinely apply the same biochemical screening procedure
to the non-GDM groups and glucose intolerant women. No significant difference was found for
remaining comparisons. One study compared women meeting CC criteria for GDM with women
demonstrating one abnormal OGTT value,86 and four studies compared women meeting CC
criteria on one abnormal OGTT value with no GDM (Figure 39).80,86,106,135 One study compared
60
women who met NDDG criteria for GDM with no GDM,152 one study compared NDDG false
positive with no GDM,67 and another study compared NGGD 1 abnormal OGTT versus no
GDM.103 Three studies compared women meeting WHO criteria for IGT with no GDM (Figure
40).133,149 Strength of evidence for all comparisons was insufficient.
Figure 38. CC GDM versus no GDM: hypoglycemia
Study or Subgroup
Chico, 2005
Langer, 2005
Pennison, 2001
CC GDM
No GDM
Events Total Events Total
23
100
10
422
555
43
202
21
5
Risk Ratio
M-H, Random, 95% CI
5767
1110
69
Risk Ratio
M-H, Random, 95% CI
1.56 [1.02, 2.37]
9.52 [6.02, 15.08]
3.21 [1.18, 8.76]
0.05 0.2
1
5
20
Favors CC GDM Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel
Figure 39. CC, 1 abnormal OGTT versus no GDM: hypoglycemia
Study or Subgroup
Chico, 2005
Corrado, 2009
Rust, 1996
Vambergue, 2000
CC1 Abnormal OGTT
No GDM
Total Events Total Weight
Events
59
152
78
131
1
9
9
24
420
Total (95% CI)
202
26
20
14
Risk Ratio
M-H, Random, 95% CI
5767
624
205
108
4.0%
27.8%
27.4%
40.8%
0.48 [0.07, 3.39]
1.42 [0.68, 2.97]
1.18 [0.56, 2.48]
1.41 [0.77, 2.60]
6704
100.0%
1.29 [0.88, 1.91]
262
43
Total events
Heterogeneity: Tau² = 0.00; Chi² = 1.20, df = 3 (P = 0.75); I² = 0%
Test for overall effect: Z = 1.29 (P = 0.20)
Risk Ratio
M-H, Random, 95% CI
0.05
0.2
1
5
20
Favors 1 Abnormal OGTT FavorsNo GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; OGTT = oral
glucose tolerance tests
Figure 40. WHO impaired glucose tolerance versus no GDM: hypoglycemia
Study or Subgroup
Jensen, 2003
Nord, 1995
Yang, 2002
Total (95% CI)
IGT
No GDM
Events Total Events Total Weight
6
2
1
Risk Ratio
M-H, Random, 95% CI
281
223
102
63 2596
3
391
1
302
76.6%
16.5%
6.9%
0.88 [0.38, 2.01]
1.17 [0.20, 6.94]
2.96 [0.19, 46.91]
606
3289
100.0%
1.00 [0.49, 2.07]
9
67
Total events
Heterogeneity: Tau² = 0.00; Chi² = 0.71, df = 2 (P = 0.70); I² = 0%
Test for overall effect: Z = 0.01 (P = 0.99)
Risk Ratio
M-H, Random, 95% CI
0.1 0.2
0.5 1
2
5 10
Favors WHO IGT Favors No GDM
CI = confidence interval; GDM = gestational diabetes mellitus; IGT = impaired glucose tolerance; M-H = Mantel-Haenszel;
WHO = World Health Organization
Hyperbilirubinemia
Eight studies presented data for hyperbilirubinemia or neonatal jaundice (Table
14).67,78,86,87,106,133,146,149 Plasma bilirubin values for the diagnosis of hyperbilirubinemia varied
amongst studies. Of the seven studies, four studies compared differing CC criterion, including
CC GDM with no GDM (Figure 41),86,146 CC GDM and one abnormal OGTT,86 CC 1 abnormal
OGTT and no GDM,106 and CC false positive and no GDM.87 Results for CC GDM versus no
GDM were not pooled due to substantial statistical heterogeneity (I2=94%). Possible sources of
heterogeneity include differences in assessing outcomes across studies and uncontrolled
differences between comparison groups. CC false positive versus no GDM showed a significant
difference with fewer cases in the group with no GDM. The other comparison involving CC
criteria (CC GDM vs. 1 abnormal OGTT) showed no significant difference between groups. One
61
study compared women with a false-positive result by NDDG criteria with no GDM; no
significant difference was found.67 Two studies compared women meeting WHO criteria for IGT
with no GDM; no significant difference was found (Figure 42).133,149 One study compared
various IADPSG thresholds for glucose intolerance.78 A significant difference was present in
comparisons of IADPSG isolated (1 value above threshold) IGT and double-isolated (two values
above threshold) IGT with no GDM, both favoring the no GDM group. No further differences
were observed for any other IADPSG comparisons.
Figure 41. CC GDM versus no GDM: hyperbilirubinemia
Study or Subgroup
Chico, 2005
Langer, 2005
GDM
No GDM
Events Total Events Total
17
78
422
555
144
23
Risk Ratio
M-H, Random, 95% CI
5767
1110
Risk Ratio
M-H, Random, 95% CI
1.61 [0.99, 2.64]
6.78 [4.31, 10.68]
0.05 0.2
1
5
20
Favors GDM Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel
Figure 42. WHO impaired glucose tolerance versus no GDM: hyperbilirubinemia
Study or Subgroup
Jensen, 2003
Nord, 1995
Total (95% CI)
IGT
No GDM
Events Total Events Total Weight
6
10
281
223
504
83
28
Risk Ratio
M-H, Random, 95% CI
2596
391
42.4%
57.6%
0.67 [0.29, 1.52]
0.63 [0.31, 1.26]
2987
100.0%
0.64 [0.38, 1.10]
111
Total events
16
Heterogeneity: Tau² = 0.00; Chi² = 0.01, df = 1 (P = 0.91); I² = 0%
Test for overall effect: Z = 1.62 (P = 0.11)
Risk Ratio
M-H, Random, 95% CI
0.2
0.5
1
2
5
Favors IGT Favors No GDM
CI = confidence interval; GDM = gestational diabetes mellitus; IGT = impaired glucose tolerance; M-H = Mantel-Haenszel;
WHO = World Health Organization
Morbidity/Mortality
Sixteen studies presented data for neonatal mortality or morbidity (Table 14).67,8588,92,93,102,103,106,135,146,149,150,154,155
No studies demonstrated a significant difference between groups
which may be due to small numbers of events within some comparisons. Six studies compared
women meeting CC criteria for GDM with no GDM (Figure 43),86,92,93,102,146,150 two studies
compared CC GDM with false positives (Figure 44),102,150 and one study compared women with
CC GDM and those with one abnormal OGTT.86 Three studies compared one abnormal OGTT
to no GDM (Figure 45),86,106,135 three studies compared women with false-positive results by CC
criteria with no GDM (Figure 46),87,102,150 and one study compared CC false positive with one
abnormal OGTT value.85 Two studies compared women with false-positive results by NDDG
criteria with no GDM (Figure 47),67,88 one study compared NDDG 1 abnormal OGTT versus no
GDM,103 three studies employed WHO criteria for IGT compared with no GDM (Figure
48),149,154,155 and another study followed IADPSG criteria for GDM diagnosis compared with no
GDM.93
62
Figure 43. CC GDM versus no GDM: morbidity/mortality
Study or Subgroup
Chico, 2005
Chou, 2010
Langer, 2005
Lapolla, 2011
Ricart, 2005
Schwartz, 1999
GDM
No GDM
Events Total Events Total Weight
0
1
0
18
0
1
Total (95% CI)
Risk Ratio
M-H, Random, 95% CI
422
489
555
112
263
154
29 5767
42 10116
0 1110
132 1815
25 6350
16 7207
10.1%
16.8%
46.6%
10.1%
16.4%
0.23 [0.01, 3.78]
0.49 [0.07, 3.57]
Not estimable
2.21 [1.40, 3.48]
0.47 [0.03, 7.73]
2.92 [0.39, 21.92]
1995
32365
100.0%
1.23 [0.46, 3.30]
244
20
Total events
Heterogeneity: Tau² = 0.49; Chi² = 6.62, df = 4 (P = 0.16); I² = 40%
Test for overall effect: Z = 0.40 (P = 0.69)
Risk Ratio
M-H, Random, 95% CI
0.01
0.1
1
10
100
Favors GDM Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel
Figure 44. CC GDM versus false positive: morbidity/mortality
Study or Subgroup
Ricart, 2005
Schwartz, 1999
GDM
False-positive
Events Total Events
Total Weight
0
1
Total (95% CI)
263
154
7
1
417
Risk Ratio
M-H, Random, 95% CI
1838
1066
49.1%
50.9%
0.46 [0.03, 8.11]
6.92 [0.44, 110.10]
2904
100.0%
1.83 [0.11, 29.41]
Total events
1
8
Heterogeneity: Tau² = 1.95; Chi² = 1.95, df = 1 (P = 0.16); I² = 49%
Test for overall effect: Z = 0.43 (P = 0.67)
Risk Ratio
M-H, Random, 95% CI
0.01
0.1
1
10
100
Favors GDM Favors False-positiv
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel
Figure 45. CC, 1 abnormal OGTT versus no GDM: morbidity/mortality
Study or Subgroup
Chico, 2005
Rust, 1996
Vambergue, 2000
1 Abnormal OGTT
No GDM
Total Events Total Weight
Events
0
15
1
59
78
131
29
40
0
268
Total (95% CI)
Risk Ratio
M-H, Random, 95% CI
5767
205
108
3.4%
93.9%
2.6%
1.63 [0.10, 26.36]
0.99 [0.58, 1.68]
2.48 [0.10, 60.20]
6080
100.0%
1.03 [0.61, 1.72]
69
16
Total events
Heterogeneity: Tau² = 0.00; Chi² = 0.42, df = 2 (P = 0.81); I² = 0%
Test for overall effect: Z = 0.10 (P = 0.92)
Risk Ratio
M-H, Random, 95% CI
0.1 0.2
0.5
1
2
5
10
Favors 1 Abnormal OGTT Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; OGTT = oral
glucose tolerance test
Figure 46. CC false positive versus no GDM: morbidity/mortality
Study or Subgroup
Bo, 2004
Ricart, 2005
Schwartz, 1999
Total (95% CI)
False-positive
No GDM
Events
Total Events Total Weight
4
7
1
315
1838
1066
3219
2
25
16
Risk Ratio
M-H, Random, 95% CI
91
6350
7207
17.4%
70.5%
12.1%
0.58 [0.11, 3.10]
0.97 [0.42, 2.23]
0.42 [0.06, 3.18]
13648
100.0%
0.80 [0.40, 1.61]
Total events
12
43
Heterogeneity: Tau² = 0.00; Chi² = 0.73, df = 2 (P = 0.69); I² = 0%
Test for overall effect: Z = 0.62 (P = 0.53)
Risk Ratio
M-H, Random, 95% CI
0.1 0.2
0.5
1
2
5 10
Favors False-positive Favors No GDM
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel
63
Figure 47. NDDG false positive versus no GDM: morbidity/mortality
Study or Subgroup
Ardawi, 2000
Stamilio, 2004
False-positive
No GDM
Events
Total Events Total Weight
2
2
187
164
Total (95% CI)
351
4
6
Risk Ratio
M-H, Random, 95% CI
529
1661
47.0%
53.0%
1.41 [0.26, 7.66]
3.38 [0.69, 16.59]
2190
100.0%
2.24 [0.70, 7.14]
4
Total events
10
Heterogeneity: Tau² = 0.00; Chi² = 0.56, df = 1 (P = 0.46); I² = 0%
Test for overall effect: Z = 1.37 (P = 0.17)
Risk Ratio
M-H, Random, 95% CI
0.1 0.2
0.5
1
2
5 10
Favors False-positive Favors No GDM
CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; NDDG = National Diabetes Data Group
Figure 48. WHO IGT versus no GDM: morbidity/mortality
Study or Subgroup
Aberg, 2001
Nord, 1995
Yang, 2002
Total (95% CI)
IGT
No GDM
Events Total Events Total Weight
1
3
2
Risk Ratio
M-H, Random, 95% CI
126
223
102
13 4515
391
7
302
2
22.9%
52.2%
24.8%
2.76 [0.36, 20.91]
0.75 [0.20, 2.88]
2.96 [0.42, 20.75]
451
5208
100.0%
1.42 [0.54, 3.75]
22
6
Total events
Heterogeneity: Tau² = 0.00; Chi² = 1.86, df = 2 (P = 0.39); I² = 0%
Test for overall effect: Z = 0.71 (P = 0.48)
Risk Ratio
M-H, Random, 95% CI
0.01
0.1
1
10
100
Favors IGT Favors No GDM
CI = confidence interval; GDM = gestational diabetes mellitus; IGT = impaired glucose tolerance; M-H = Mantel-Haenszel;
WHO = World Health Organization
Long Term
One study presented data on long term health outcomes for infants and children (i.e.,
prevalence of childhood obesity).132
Prevalence of Childhood Obesity
Significant differences were found between women meeting thresholds for CC GDM in
comparison with those without GDM, favoring the no GDM group.132 The CC false-positive
group was favored compared with women meeting CC GDM criteria (Table 14). These findings
should be interpreted cautiously because this study did not adjust for maternal BMI, one of the
most important predictors of childhood obesity. No significant differences were found for the
remaining comparisons (Table 14).
64
Table 14. Evidence summary table: fetal/neonatal outcomes
Outcome
Macrosomia >4,000 g
Macrosomia >4,500 g
Comparison
CC GDM vs. no
GDM
CC GDM vs. false
positive
CC GDM vs. 1
abnormal OGTT
CC 1 abnormal
OGTT vs. no GDM
CC false positive vs.
no GDM
CC 1 abnormal
OGTT vs. false
positive
NDDG GDM
(unrecognized) vs.
no GDM
NDDG false positive
vs.
no GDM
WHO GDM vs. no
GDM
WHO IGT vs. no
GDM
IADPSG GDM vs. no
GDM
CC GDM vs. no
GDM
CC GDM vs. false
positive
CC false positive vs.
no GDM
NDDG GDM
(unrecognized) vs.
no GDM
Studies
Participants
10
42,874
5
8,241
3
1,101
7
16,063
5
14,852
3
1,873
1
Effect
Estimate*
1.61 [1.35,
1.92]
1.36 [1.10,
1.68]
0.98 [0.69,
1.41]
1.44 [1.13,
1.82]
1.02 [0.85,
1.24]
I
2
Favors
42%
No GDM
45%
False
positive
0%
-
14%
No GDM
31%
-
1.40 [0.89,
2.20]
48%
-
80
5.60 [2.04,
15.35]
NA
No GDM
4
4,501
1.44 [1.10,
1.89]
0%
No GDM
1
542
1
2,885
2
2,130
3
21,549
2
1,391
2
8,315
1
80
3.33 [0.49,
22.70]
1.26 [1.06,
1.50]
2.09 [0.39,
11.33]
2.52 [1.65,
3.84]
1.71 [0.56,
5.24]
1.48 [0.91,
2.39]
26.76 [1.45,
493.62]
65
NA
NA
39%
0%
No GDM
No GDM
63%
-
44%
-
NA
No GDM
‡
Table 14. Evidence summary table: fetal/neonatal outcomes (continued)
Outcome
Shoulder dystocia
Comparison
CC GDM vs. no
GDM
CC GDM vs. false
positive
CC 1 abnormal
OGTT vs. no GDM
CC 1 abnormal
OGTT vs. false
positive
NDDG GDM
(unrecognized) vs.
no GDM
NDDG false positive
vs. no GDM
WHO IGT vs. no
GDM
IADPSG IGT vs. no
GDM
IADPSG IFG vs. no
GDM
IADPSG IGT-2 vs.
no GDM
IADPSG IGT IFG vs.
no GDM
IADPSG IGT vs. IFG
IADPSG IGT vs.
IGT-2
IADPSG IGT vs. IGT
IFG
IADPSG IFG vs.
IGT-2
IADPSG IFG vs. IGT
IFG
IADPSG IGT-2 vs.
IGT IFG
Effect
Estimate*
2.86 [1.81,
4.51]
1.49 [0.97,
2.30]
0.20 [0.02,
1.82]
Participants
5
27,473
1
3,577
1
239
1
410
5.09 [1.14,
22.66]
NA
False
positive
1
80
6.00 [1.09,
32.95]
NA
No GDM
1
1,825
NA
No GDM
1
2,885
NA
No GDM
1
7,411
1
7,906
1
7,103
1
7,351
1
1,277
1
474
1
722
1
969
1
1,217
1
414
66
2.79 [1.30,
6.01]
2.18 [1.02,
4.67]
1.21 [0.76,
1.92]
1.48 [1.10,
1.98]
1.58 [0.67,
3.72]
1.82 [1.21,
2.75]
0.82 [0.48,
1.38]
0.76 [0.29,
2.00]
0.66 [0.36,
1.21]
0.94 [0.38,
2.28]
0.81 [0.50,
1.31]
0.87 [0.34,
2.21]
I
2
Studies
0%
Favors
No GDM
NA
-
NA
-
NA
NA
NA
NA
No GDM
No GDM
NA
-
NA
-
NA
-
NA
-
NA
-
NA
-
‡
Table 14. Evidence summary table: fetal/neonatal outcomes (continued)
Outcome
Comparison
CC GDM vs. no
GDM
Neonatal hypoglycemia
CC GDM vs. 1
abnormal OGTT
CC 1 abnormal
OGTT vs. no GDM
NDDG GDM vs. no
GDM
NDDG false positive
vs. no GDM
NDDG, 1 abnormal
OGTT vs. no GDM
WHO IGT vs. no
GDM
CC GDM vs. no
GDM
Hyperbilirubinemia
CC GDM vs. 1
abnormal OGTT
CC false positive vs.
no GDM
CC 1 abnormal
OGTT vs. no GDM
NDDG False
positive vs. no GDM
WHO IGT vs. no
GDM
IADPSG IGT vs. no
GDM
IADPSG IFG vs. no
GDM
IADPSG IGT-2 vs.
no GDM
Studies
Participants
3
7,966
1
481
4
7,124
1
80
1
716
1
699
3
3,895
2
7,854
1
481
1
406
1
239
1
716
2
3,491
1
7,411
1
7,906
1
7,103
67
Effect
Estimate*
Results not
pooled due
to
substantial
heterogeneit
y.
3.22 [0.44,
23.37]
1.29 [0.88,
1.91]
Not
†
Estimable
2.83 [0.58,
13.89]
9.60 [0.86,
106.73]
1.00 [0.49,
2.07]
Results not
pooled due
to
substantial
heterogeneit
y.
2.38 [0.32,
17.53]
3.03 [1.12,
8.23]
4.19 [0.20,
88.20]
1.07 [0.68,
1.70]
0.64 [0.38,
1.10]
1.32 [1.06,
1.64]
1.03 [0.87,
1.23]
1.55 [1.03,
2.35]
I
2
Favors
94%
-
NA
-
0%
-
NA
-
NA
-
NA
-
0%
-
94%
-
NA
-
NA
No GDM
NA
-
NA
-
0%
-
NA
NA
NA
No GDM
No GDM
‡
Table 14. Evidence summary table: fetal/neonatal outcomes (continued)
Outcome
Hyperbilirubinemia
(continued)
Fetal birth trauma/injury
Fetal morbidity/mortality
Comparison
Studies
Participants
IADPSG IGT IFG vs.
no GDM
1
7,351
IADPSG IGT vs. IFG
1
1,277
1
474
1
722
1
969
1
1,217
1
414
1
14,213
1
80
2
1,018
6
34,360
2
3,321
1
481
3
6,348
3
16,867
1
410
2
2,541
IADPSG IGT vs.
IGT-2
IADPSG IGT vs. IGT
IFG
IADPSG IFG vs.
IGT-2
IADPSG IFG vs. IGT
IFG
IADPSG IGT-2 vs.
IGT IFG
CC GDM vs. no
GDM
NDDG GDM vs. no
GDM
WHO IGT vs. no
GDM
CC GDM vs. no
GDM
CC GDM vs. false
positive
CC GDM vs. 1
abnormal OGTT
CC 1 abnormal
OGTT vs. no GDM
CC false positive vs.
no GDM
CC false positive vs.
1 abnormal OGTT
NDDG false positive
vs. no GDM
68
Effect
Estimate*
0.97 [0.74,
1.29]
1.27 [0.98,
1.66]
0.85 [0.54,
1.34]
1.35 [0.96,
1.91]
0.67 [0.43,
1.03]
1.06 [0.78,
1.46]
1.60 [0.98,
2.61]
1.19 [0.68,
2.08]
34.41 [1.95,
608.47]
0.29 [0.04,
2.41]
1.23 [0.46,
3.30]
1.83 [0.11,
29.41]
Not
†
estimable
1.03 [0.61,
1.72]
0.80 [0.40,
1.61]
Not
†
estimable
2.24 [0.70,
7.14]
I
2
Favors
NA
-
NA
-
NA
-
NA
-
NA
-
NA
-
NA
-
NA
-
NA
No GDM
NA
-
40%
-
49%
-
NA
-
0%
-
0%
-
NA
-
0%
-
‡
Table 14. Evidence summary table: fetal/neonatal outcomes (continued)
Effect
2
‡
I
Favors
Estimate*
NDDG 1 abnormal
0.94 [0.04,
1
699
NA
OGTT vs. no GDM
19.69]
Fetal morbidity/mortality
WHO IGT vs. no
1.42
3
5,659
0%
(continued)
GDM
[0.54,3.75]
IADPSG GDM vs.
2.21 [1.40,
1
1927
NA
no GDM
3.48]
CC GDM vs. no
1.48 [1.20,
1
7,782
NA
No GDM
GDM
1.82]
CC GDM vs. false
1.49
False
1
1,172
NA
positive
[1.18,1.88]
positive
1.30 [0.98,
CC GDM vs. 1
1
461
NA
abnormal OGTT
1.72]
Prevalence of childhood
obesity
CC false positive vs.
0.99 [0.88,
1
8,608
NA
no GDM
1.12]
CC false positive vs.
0.81 [0.56,
1
1,287
NA
1 abnormal OGTT
1.18]
CC 1 abnormal
1.14 [0.94,
1
7,897
NA
OGTT vs. no GDM
1.38]
CC = Carpenter-Coustan; GDM = gestational diabetes mellitus; IFG = impaired fasting glycemia; IGT = impaired glucose tolerance; IGT-2 = double impaired glucose tolerance;
IADPSG = International Association of Diabetes and Pregnancy Study Groups; NDDG = National Diabetes Data Group; NA = not applicable; OGTT = oral glucose tolerance test;
WHO = World Health Organization.
*Effect estimates are risk ratios with 95% confidence intervals.
†Not estimable due to zero events in both groups.
‡Where the result was statistically significant, we have listed the group that had the better outcome (e.g., lower incidence of macrosomia).
Outcome
Comparison
Studies
Participants
69
Table 15. Strength of evidence summary table: fetal/neonatal outcomes
Outcome
Macrosomia >4,000 g
Macrosomia >4,500 g
Shoulder dystocia
10
5
Risk of
Bias
High
High
Consistent
Consistent
Direct
Direct
Precise
Precise
Low
Low
3
High
Consistent
Direct
Precise
Low
7
High
Consistent
Direct
Precise
Low
5
High
Consistent
Direct
Precise
Low
3
High
Inconsistent
Direct
Precise
Insufficient
1
High
Unknown
Direct
Imprecise
Insufficient
4
High
Consistent
Direct
Precise
Low
1
1
2
3
2
2
High
high
High
High
High
High
Unknown
Unknown
Consistent
Consistent
Inconsistent
Consistent
Direct
Direct
Direct
Direct
Direct
Direct
Imprecise
Precise
Imprecise
Precise
Imprecise
Imprecise
Insufficient
Insufficient
Insufficient
Low
Insufficient
Insufficient
1
High
Unknown
Direct
Imprecise
Insufficient
5
1
High
High
Consistent
Unknown
Direct
Direct
Precise
Imprecise
Low
Insufficient
1
High
Unknown
Direct
Imprecise
Insufficient
1
High
Unknown
Direct
Imprecise
Insufficient
1
High
Unknown
Direct
Imprecise
Insufficient
1
High
Unknown
Direct
Imprecise
Insufficient
1
1
1
1
1
High
High
High
High
High
Unknown
Unknown
Unknown
Unknown
Unknown
Direct
Direct
Direct
Direct
Direct
Imprecise
Imprecise
Precise
Imprecise
Precise
Insufficient
Insufficient
Insufficient
Insufficient
Insufficient
Comparison
Studies
CC GDM vs. no GDM
CC GDM vs. false positive
CC GDM vs. 1 abnormal
OGTT
CC 1 abnormal OGTT vs. no
GDM
CC false positive vs. no GDM
CC 1 abnormal OGTT vs. false
positive
NDDG GDM (unrecognized)
vs. no GDM
NDDG false positive vs. no
GDM
WHO GDM vs. no GDM
WHO IGT vs. no GDM
IADPSG GDM vs. no GDM
CC GDM vs. no GDM
CC GDM vs. false positive
CC false positive vs. no GDM
NDDG GDM (unrecognized)
vs. no GDM
CC GDM vs. no GDM
CC GDM vs. false positive
CC 1 abnormal OGTT vs. no
GDM
CC 1 abnormal OGTT vs. false
positive
NDDG GDM (unrecognized)
vs. no GDM
NDDG false positive vs. no
GDM
WHO IGT vs. no GDM
IADPSG IGT vs. no GDM
IADPSG IFG vs. no GDM
IADPSG IGT-2 vs. no GDM
IADPSG IGT IFG vs. no GDM
70
Consistency
Directness
Precision
SOE
Table 15. Strength of evidence summary table: fetal/neonatal outcomes (continued)
Outcome
Comparison
Studies
Risk of
Bias
High
High
High
High
High
High
High
Consistency
Directness
Precision
SOE
IADPSG IGT vs. IFG
1
Unknown
Direct
Imprecise
Insufficient
IADPSG IGT vs. IGT-2
1
Unknown
Direct
Imprecise
Insufficient
IADPSG IGT vs. IGT IFG
1
Unknown
Direct
Imprecise
Insufficient
Shoulder dystocia (continued)
IADPSG IFG vs. IGT-2
1
Unknown
Direct
Imprecise
Insufficient
IADPSG IFG vs. IGT IFG
1
Unknown
Direct
Imprecise
Insufficient
IADPSG IGT-2 vs. IGT IFG
1
Unknown
Direct
Imprecise
Insufficient
CC GDM vs. no GDM
3
Inconsistent
Direct
Imprecise
Insufficient
CC GDM vs. 1 abnormal
1
High
Unknown
Direct
Imprecise
Insufficient
OGTT
CC 1 abnormal OGTT vs. no
4
High
Consistent
Direct
Imprecise
Insufficient
GDM
Neonatal hypoglycemia
NDDG GDM vs. no GDM
1
High
Unknown
Direct
NA
Insufficient
NDDG false positive vs. no
1
High
Unknown
Direct
Imprecise
Insufficient
GDM
NDDG 1 abnormal OGTT vs.
1
High
Unknown
Direct
Imprecise
Insufficient
no GDM
WHO IGT vs. no GDM
3
High
Consistent
Direct
Imprecise
Insufficient
1
High
Unknown
Direct
Imprecise
Insufficient
CC GDM vs. no GDM
Fetal birth trauma/injury
NDDG GDM vs. no GDM
1
High
Unknown
Direct
Imprecise
Insufficient
WHO IGT vs. no GDM
2
High
Consistent
Direct
Imprecise
Insufficient
CC = Carpenter-Coustan; GDM = gestational diabetes mellitus; IGT = impaired glucose tolerance; IGT-2 = double impaired glucose tolerance; IADPSG = International
Association of Diabetes and Pregnancy Study Groups; IFG = impaired fasting glucose; NA = not applicable; NDDG = National Diabetes Data Group; OGTT = oral glucose
tolerance test; SOE = strength of evidence; WHO = World Health Organization.
71
Key Question 4. Does treatment modify the health outcomes of mothers
who meet various criteria for GDM and offspring?
Description of Included Studies
Eleven studies met the inclusion criteria for Key Question 4.50,54,92,95-98,146,148,152,160 The
studies are described in Appendix D. All studies compared diet modification, glucose monitoring
and insulin as needed with standard care. Five of the studies were RCTs,50,54,96-98 while six were
retrospective cohort studies.92,95,146,148,152,160 The studies were published between 1996 and 2010
(median year 2005). Two studies had two associated publications reporting initial and longer
term outcomes.50,54 Five studies were from the United States,54,95,98,146,152 two from Italy,97,148 two
from Canada,96,160 and one each from Taiwan92 and Australia.50 The screening test used in most
studies was OGCT with a 100 g OGTT assessed using CC criteria, except for the studies from
Canada and Australia that used a OGCT with a 75 g OGTT. Diagnostic testing in all studies
occurred at or after 24 weeks’ gestation. Among these studies a variety of glucose inclusion
criteria were used, varying from 50 g screen positive with nondiagnostic OGTTs to women who
met National Diabetes Data Group criteria for a diagnosis of GDM. The two largest RCTs50,163
by Crowther et al. and Landon et al. used different glucose thresholds for entry in their trials:
WHO and CC criteria with a fasting glucose <95 mg/dL (5.3 mmol/L), respectively; however,
the mean glucose levels of women at study entry were remarkably similar between these two
studies.
Methodological Quality of Included Studies
The methodological quality of the included studies is described in Appendix C3. The risk of
bias for the RCTs was low for one trial,50 unclear for three trials,54,97,98 and high for one trial.96
The trials that were unclear most commonly did not report detailed methods for sequence
generation and allocation concealment. The trial assessed as high risk of bias was due to lack of
blinding for outcome assessment and incomplete outcome data.
The six cohort studies were all considered high quality, with overall quality scores of 7 to 9
on a 9-point scale. Three studies received full scores of 9.54,152,160 One study received a score of
8/9 because the study population was a selected (non-representative) group (i.e., participants at a
diabetic center).148 Two studies received a score of 7/9. One study obtained this score due to the
study population considered only “somewhat” representative (all women were cared for under a
single health plan); as well as a lack of control for potential confounders including age, race,
BMI, previous GDM, or family history of DM.95 The absence of control for any potential
confounders was also the reason for the lower score in the second study. 92
Key Points
•
•
A variety of glucose threshold criteria were used for inclusion across studies. For
outcomes where results were inconsistent between studies, different study glucose
threshold entry criteria did not explain the variation.
Results for some outcomes were driven by the two largest RCTs, the Maternal Fetal
Medicine Unit (MFMU)54 and the Australian Carbohydrate Intolerance in Pregnancy
Study (ACHOIS),50 which had unclear and low risk of bias, respectively.
72
Maternal Outcomes
•
•
•
•
•
•
•
There was moderate evidence from 3 RCTs showing a significant difference for
preeclampsia with fewer cases in the treated group.
There was inconsistency across studies in terms of differences in maternal weight gain (4
RCTs and 2 cohort studies). The strength of evidence was considered insufficient due to
inconsistency across studies and imprecision in effect estimates.
No differences between groups were found for cesarean section (5 RCTs, 6 cohorts) or
unplanned cesarean section (1 RCT, 1 cohort).
There was inconsistency across studies in terms of induction of labor with no difference
found for the 2 RCTs overall and a significant difference favoring the treatment group
among the one cohort study included.
Only one RCT reported on BMI at delivery and showed a significant difference with
lower BMI in the treated group.
Only one cohort study reported maternal birth trauma (i.e., postpartum hemorrhage) and
showed no difference between groups.
There was no evidence for long-term maternal outcomes such as type 2 diabetes mellitus,
obesity, and hypertension.
Short-Term Outcomes in the Offspring
•
•
•
•
•
•
•
There was insufficient evidence for birth injury. There was inconsistency across studies
with the 2 RCTs showing no difference and the one cohort study showing a difference in
favor of the treated group. The low number of events and participants across all studies
resulted in imprecise estimates.
The incidence of shoulder dystocia was significantly lower in the treated groups, and this
finding was consistent for the 3 RCTs and 4 cohort studies. Overall, the evidence for
shoulder dystocia was considered moderate showing a difference in favor of the treated
group.
For other injury outcomes, including brachial plexus injury (1 RCT, 1 cohort), and
clavicular fractures (1 RCT, 1 cohort), the results were inconsistent across designs with
the RCTs showing no differences between groups and the cohort study showing a
significant difference in favor of the treated group.
There was low evidence of no difference between groups for neonatal hypoglycemia
based on four RCTs and 2 cohort studies.
For outcomes related to birthweight (including macrosomia >4,000 g, macrosomia
>4,500 g, actual birthweight, and large for gestational age), differences were often
observed favoring the treated groups. The strength of evidence was moderate for
macrosomia >4,000 g suggesting a benefit of treatment.
There was no difference in hyperbilirubinemia for the 3 RCTs, while the one cohort study
showed a significant difference in favor of the treated group.
There were no differences observed across studies for perinatal death (3 RCTs, 3
cohorts). Two RCTs showed no difference between groups for respiratory distress
syndrome, while one cohort study found a significant difference favoring the treated
group for “respiratory complications.” Several studies assessed APGAR scores, and
while differences were found in both the RCT and cohort study for APGAR at 1 minute,
no differences were found among the 2 RCTs and 1 cohort study at 5 minutes.
73
Long-Term Outcomes in the Offspring
•
•
One RCT followed patients for 7 to 11 years and found no differences for impaired
glucose tolerance or type 2 diabetes mellitus, although the strength of evidence was
considered insufficient.
No differences were observed in single studies that assessed BMI >95 (7-11 year
followup) and BMI >85 percentile (5-7 year followup). Overall, pooled results showed no
difference in BMI and the strength of evidence was considered low.
Detailed Synthesis
Detailed results are described by outcome in the sections that follow. We first describe the
maternal outcomes, followed by fetal/neonatal/child outcomes. We present meta-graphs when
two or more studies were pooled. These are displayed after the description of results for each
outcome. A detailed table of results is presented at the end of each of the maternal and
fetal/neonatal/child sections (Table 16 and Table 17, respectively). The strength of evidence for
key outcomes is presented in Table 18.
Maternal Outcomes
Short Term
Cesarean Delivery
All studies provided data on cesarean delivery (Table 16).50,54,92,95-98,146,148,152,160 There was
no significant difference in the pooled estimates for the RCTs (risk ratio [RR] 0.90, 95% CI 0.79
to 1.01, n = 2,613) or for the cohort studies (RR 1.09, 95% CI 0.90 to 1.31, n = 3,110; Figure
49). The results were statistically homogeneous across all studies. One RCT50 and one cohort
study95 reported emergency cesarean deliveries and found no difference (RCT, RR 0.81, 95% CI
0.62 to 1.05, n = 1,000; cohort, RR 0.83, 95% CI 0.33 to 2.06, n = 126).
74
Figure 49. Effect of treatment on outcomes of women with GDM: cesarean delivery
Study or Subgroup
1.1.1 RCT
Bevier 1999
Bonomo 2005
Crowther 2005
Garner 1997
Landon 2009
Subtotal (95% CI)
Treatment
No treatment
Total Weight
Events Total Events
5
42
152
30
128
35
150
490
149
476
1300
12
44
164
28
154
Risk Ratio
M-H, Random, 95% CI
1.6%
48
150 11.3%
510 43.1%
6.7%
150
455 37.3%
1313 100.0%
Risk Ratio
M-H, Random, 95% CI
0.57 [0.22, 1.47]
0.95 [0.67, 1.36]
0.96 [0.80, 1.16]
1.08 [0.68, 1.71]
0.79 [0.65, 0.97]
0.90 [0.79, 1.01]
402
357
Total events
Heterogeneity: Tau² = 0.00; Chi² = 3.68, df = 4 (P = 0.45); I² = 0%
Test for overall effect: Z = 1.81 (P = 0.07)
1.1.2 Cohort studies
Adams 1998
Bonomo 1997
Chou, 2010
Fassett 2007
Langer 2005
Naylor, 1996
Subtotal (95% CI)
99
7
40
21
258
48
373
26
233
69
1110
143
1954
4
26
32
19
132
34
4.5%
16
6.4%
88
325 15.0%
57 11.5%
555 43.0%
115 19.6%
1156 100.0%
1.06 [0.45, 2.52]
0.91 [0.45, 1.85]
1.74 [1.13, 2.69]
0.91 [0.55, 1.52]
0.98 [0.81, 1.17]
1.14 [0.79, 1.63]
1.09 [0.90, 1.31]
247
473
Total events
Heterogeneity: Tau² = 0.01; Chi² = 6.47, df = 5 (P = 0.26); I² = 23%
Test for overall effect: Z = 0.88 (P = 0.38)
Test for subgroup differences: Chi² = 2.93, df = 1 (P = 0.09), I² = 65.9%
0.2
0.5
1
2
5
Favors treatment Favors no treatment
CI = confidence interval; GDM = gestational diabetes mellitus; RCT = randomized controlled trial; M-H = Mantel-Haenszel
Induction of Labor
Three studies provided data on induction of labor50,54,146 but results differed significantly
across the studies (Table 16). Two RCTs showed no significant difference overall (RR 1.16, 95%
CI 0.91 to 1.49, n = 1,931), although there was important statistical heterogeneity between
studies (I2 = 69%). One RCT showed a significant difference favoring no treatment,50 while the
other study showed no difference (Figure 50).54 Different study protocols may account for the
heterogeneity of results between studies. In the study that showed more inductions of labor in the
treatment group, no recommendations were provided regarding obstetrical care, thus replicating
usual clinical care of women with GDM. In the other study, antenatal surveillance was reserved
for standard obstetrical indications. In contrast the one cohort study showed a significant
difference with fewer inductions in the treatment group (RR 0.63, 95% CI 0.55 to 0.72, n =
1,665).146 Baseline differences in the study populations and regional practices may have
accounted for the different results between studies. Further, the comparison group in the cohort
study was women who presented late for obstetrical care which confounds the relationship
between induction and GDM treatment. Furthermore, the cohort study protocol was to deliver
these women within one week of GDM diagnosis so the outcome of induction was substantially
confounded by different delivery protocols between treatment and nontreatment groups.
75
Figure 50. Effect of treatment on outcomes of women with GDM: induction of labor
Study or Subgroup
1.6.1 RCT
Crowther 2005
Landon 2009
Subtotal (95% CI)
Treatment
No treatment
Events Total Events
Total Weight
189
130
490
476
966
150
122
Risk Ratio
M-H, Random, 95% CI
510 52.8%
455 47.2%
965 100.0%
Risk Ratio
M-H, Random, 95% CI
1.31 [1.10, 1.56]
1.02 [0.82, 1.26]
1.16 [0.91, 1.49]
Total events
319
272
Heterogeneity: Tau² = 0.02; Chi² = 3.27, df = 1 (P = 0.07); I² = 69%
Test for overall effect: Z = 1.20 (P = 0.23)
1.6.2 Cohort Studies
Langer 2005
Subtotal (95% CI)
303
1110
1110
242
555 100.0%
555 100.0%
0.63 [0.55, 0.72]
0.63 [0.55, 0.72]
Total events
303
242
Heterogeneity: Not applicable
Test for overall effect: Z = 6.81 (P < 0.00001)
Test for subgroup differences: Chi² = 18.61, df = 1 (P < 0.0001), I² = 94.6%
0.5
0.7
1
1.5
2
Favors treatment Favors no treatment
CI = confidence interval; GDM = gestational diabetes mellitus; RCT = randomized controlled trial; M-H = Mantel-Haenszel
Preeclampsia
Three RCTs and one cohort study provided data on preeclampsia (Table 16).50,54,98,160 Pooled
estimate for the RCTs showed a significant difference favoring the treated group (RR 0.62; 95%
CI, 0.43 to 0.89, n = 2,014) with minimal statistical heterogeneity across studies (I2 = 16%;
Figure 51). The strength of evidence was considered moderate (Table 18). One of the studies
also reported preeclampsia or gestational hypertension as a combined outcome,54 and also
showed a significant difference favoring the treatment group (RR 0.63; 95% CI, 0.44 to 0.92, n =
931). In all three trials, there was no significant difference between groups in gestational age at
delivery.
76
Figure 51. Effect of treatment on outcomes of women with GDM: preeclampsia
CI = confidence interval; GDM = gestational diabetes mellitus; RCT = randomized controlled trial; M-H = Mantel-Haenszel
Birth Trauma
One study provided data on maternal birth trauma (postpartum hemorrhage).92 No
significant difference was observed between groups (Table 16).
Weight Gain
Six studies provided data on weight gain (Table 16).50,54,95-97,152 Pooled results for the RCTs
are not presented due to substantial heterogeneity (I2=88%). Two RCTs showed no significant
difference,96,97 while two large RCTs showed a significant difference with less weight gain in the
treatment group (Figure 52).50,54 Given the high BMIs of the women studied in these large RCTs,
less gestational weight gain in the treatment group could be interpreted as a beneficial finding.
Pooled results for the cohort studies showed no significant difference between groups (mean
difference [MD] -1.04; 95% CI, -2.89 to 0.81, n = 515). The strength of evidence was considered
insufficient for this outcome (Table 18).
77
Figure 52. Effect of treatment on outcomes of women with GDM: weight gain
CI = confidence interval; GDM = gestational diabetes mellitus; IV = inverse variance; RCT = randomized controlled trial; SD =
standard deviation
BMI at Delivery
Only one RCT reported BMI at delivery and showed a significantly lower BMI in the treated
group compared with the untreated group (mean BMI 31.3 vs. 32.3; mean difference -1.00; 95%
CI, -1.67 to -0.33, n = 931) (Table 16).54
Table 16. Evidence summary for Key Question 4: maternal outcomes
Outcome
Cesarean section
Unplanned cesarean
section
Induction of labor
Preeclampsia
Preeclampsia or
gestational
hypertension
Weight gain (kg)
2
RCT
Cohort
RCT
Cohort
RCT
Cohort
RCT
Cohort
RCT
Number of
Studies
5
6
1
1
2
1
3
1
1
Number of
Participants
2613
3110
1000
126
1931
1665
2014
258
931
0.90 [0.79, 1.01]
1.09 [0.90, 1.31]
0.81 [0.62, 1.05]
0.83 [0.33, 2.06]
1.16 [0.91, 1.49]
0.63 [0.55, 0.72]
0.62 [0.43, 0.89]
0.97 [0.43, 2.15]
0.63 [0.44, 0.92]
I
(%)
0
23
NA
NA
69
NA
16
NA
NA
Cohort
1
874
0.30 [0.15, 0.62]
NA
-
RCT
4
2530
88
-
Source
Cohort
2
Maternal birth trauma
Cohort
1
BMI at delivery
RCT
1
NA = not applicable; RCT = randomized controlled trial
*Risk ratios unless otherwise specified.
†Mean difference.
515
874
931
78
Effect Estimate*
Pooled estimate
not reported due to
heterogeneity
†
-1.04 [-2.89, 0.81]
0.95 [0.21, 4.28]
†
-1.00 [-1.67, -0.33]
8
NA
NA
Favors
Treatment
Treatment
Treatment
Treatment
Fetal/Neonatal/Child Outcomes
Short Term
Birthweight
All studies reported birthweights for the infants (Table 17).50,54,92,95-98,146,148,152,160 Pooled
estimate for the RCTs showed significantly lower incidence of birthweights >4,000 g among
infants in the treated groups (RR 0.50, 95% CI, 0.35 to 0.71; Figure 53); however, there was
moderate heterogeneity across studies. Pooled estimates were not reported for the cohort studies
because of substantial heterogeneity (I2=86%). Three of the studies96,152,160 also reported the
incidence of birthweights >4,500 g and showed no significant differences between groups. In
terms of actual birthweight (Figure 54), the five RCTs showed significantly lower mean
birthweights among the treated group (MD -120.8; 95% CI, -163.4 to -78.2, n = 2,670). The two
cohort studies showed substantial heterogeneity with one study showing a significantly lower
mean birthweight in the treated group and the second cohort study showing no difference
between groups.
Figure 53. Effect of treatment on outcomes for offspring of women with GDM: birthweight >4,000 g
Study or Subgroup
2.5.1 RCT
Bevier 1999
Bonomo 2005
Crowther 2005
Garner 1997
Landon 2009
Treatment
No treatment
Total
Events Total Events
Risk Ratio
M-H, Random, 95% CI
1
8
49
24
28
35
150
506
149
477
12
16
110
28
65
48
150
524
150
454
0.11 [0.02, 0.84]
0.50 [0.22, 1.13]
0.46 [0.34, 0.63]
0.86 [0.53, 1.42]
0.41 [0.27, 0.63]
66
0
36
10
78
15
373
26
385
69
1110
143
7
11
22
8
93
33
16
88
489
57
555
115
0.40 [0.22, 0.73]
0.14 [0.01, 2.35]
2.08 [1.24, 3.47]
1.03 [0.44, 2.44]
0.42 [0.32, 0.56]
0.37 [0.21, 0.64]
Risk Ratio
M-H, Random, 95% CI
2.5.2 Cohort studies
Adams 1998
Bonomo 1997
Chou, 2010
Fassett 2007
Langer 2005
Naylor, 1996
0.01
0.1
1
10
100
Favors treatment Favors no treatment
CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; RCT = randomized controlled trial
79
Figure 54. Effect of treatment on outcomes for offspring of women with GDM: birthweight
(continuous)
Treatment
SD Total
Mean
Study or Subgroup
2.10.1 RCT
Bevier 1999
Bonomo 2005
Crowther 2005
Garner 1997
Landon 2009
No treatment
SD Total
Mean
459
3,311
436
3,365
551
3,335
575
3,437
3,302 502.4
511
3,600
35
462
150 3,436.6
660
3,482
506
601
3,544
149
3,408 589.4
485
528
3,511.2
3,476.7 554.7
713
3,866
373
69 3,389.4 649.8
Mean Difference
IV, Random, 95% CI
Mean Difference
IV, Random, 95% CI
48 -289.00 [-498.81, -79.19]
-71.60 [-173.26, 30.06]
150
524 -147.00 [-221.15, -72.85]
150 -107.00 [-240.32, 26.32]
473 -106.00 [-175.43, -36.57]
2.10.2 Cohort studies
Adams 1998
Fassett 2007
16
57
-354.80 [-708.25, -1.35]
87.30 [-126.21, 300.81]
-500 -250
0
250
500
Favors treatment Favors no treatment
CI = confidence interval; GDM = gestational diabetes mellitus; IV = inverse variance; RCT = randomized controlled trial; SD =
standard deviation
Large for Gestational Age (LGA)
There was a significant difference in LGA with the treatment group having fewer cases
among both the three RCTs50,54,97 (RR 0.56; 95% CI, 0.45 to 0.69, n = 2,261) and the four cohort
studies (RR 0.43; 95% CI, 0.27 to 0.70, n = 2,294) (Table 17).95,148,152,152 The results for the
cohort studies showed moderate statistical heterogeneity (I2 = 58%) (Figure 55). One study
appeared to be an outlier,95 and when removed from the analysis there was no heterogeneity.
Figure 55. Effect of treatment on outcomes for offspring of women with GDM: large for gestational
age (LGA)
Study or Subgroup
2.13.1 RCT
Bonomo 2005
Crowther 2005
Landon 2009
Subtotal (95% CI)
Treatment
No treatment
Total Weight
Events Total Events
9
68
34
150
506
477
1133
21
115
66
8.3%
150
524 61.8%
454 29.9%
1128 100.0%
Risk Ratio
M-H, Random, 95% CI
Risk Ratio
M-H, Random, 95% CI
0.43 [0.20, 0.90]
0.61 [0.47, 0.81]
0.49 [0.33, 0.73]
0.56 [0.45, 0.69]
202
111
Total events
Heterogeneity: Tau² = 0.00; Chi² = 1.34, df = 2 (P = 0.51); I² = 0%
Test for overall effect: Z = 5.34 (P < 0.00001)
2.13.2 Cohort studies
Adams 1998
Bonomo 1997
Fassett 2007
Langer 2005
Subtotal (95% CI)
50
3
11
119
373
26
69
1110
1578
7
27
8
163
16 26.0%
88 13.1%
57 18.8%
555 42.1%
716 100.0%
0.31 [0.17, 0.57]
0.38 [0.12, 1.14]
1.14 [0.49, 2.63]
0.37 [0.29, 0.45]
0.43 [0.27, 0.70]
205
183
Total events
Heterogeneity: Tau² = 0.13; Chi² = 7.18, df = 3 (P = 0.07); I² = 58%
Test for overall effect: Z = 3.45 (P = 0.0006)
Test for subgroup differences: Chi² = 0.88, df = 1 (P = 0.35), I² = 0%
0.1 0.2
0.5
1
2
5 10
Favors treatment Favors no treatment
CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; RCT = randomized controlled trial
80
Shoulder Dystocia
Seven studies provided data on shoulder dystocia (Table 17).50,54,92,95,98,146,152 Pooled
estimates from three RCTs50,54,98 showed a significant difference favoring the treated group (RR
0.42; 95% CI, 0.23 to 0.77, n = 2,044; (Figure 56). The four cohort studies92,95,146,152 also showed
a significant difference favoring the treated group (RR 0.38; 95% CI, 0.19 to 0.78, n = 3,054).
There was no statistical heterogeneity across studies. Overall, the strength of evidence was
considered moderate showing a difference in favor of the treated group. Shoulder dystocia was
reduced for all studies combined; however, individual studies that included women with milder
forms of glucose intolerance (i.e., OGCT screen positive OGTT negative, one RCT 98 and one
cohort study95) showed no differences.
Figure 56. Effect of treatment on outcomes for offspring of women with GDM: shoulder dystocia
Study or Subgroup
2.2.1 RCT
Bevier 1999
Crowther 2005
Landon 2009
Subtotal (95% CI)
Treatment
No treatment
Total Weight
Events Total Events
1
7
7
35
506
476
1017
2
16
18
6.4%
48
524 45.9%
455 47.7%
1027 100.0%
Risk Ratio
M-H, Random, 95% CI
Risk Ratio
M-H, Random, 95% CI
0.69 [0.06, 7.27]
0.45 [0.19, 1.09]
0.37 [0.16, 0.88]
0.42 [0.23, 0.77]
36
15
Total events
Heterogeneity: Tau² = 0.00; Chi² = 0.27, df = 2 (P = 0.87); I² = 0%
Test for overall effect: Z = 2.83 (P = 0.005)
2.2.2 Cohort studies
Adams 1998
Chou, 2010
Fassett 2007
Langer 2005
Subtotal (95% CI)
13
2
2
10
373
385
69
1110
1937
3
2
2
14
16 28.9%
489 11.9%
57 12.2%
555 47.0%
1117 100.0%
0.19 [0.06, 0.59]
1.27 [0.18, 8.98]
0.83 [0.12, 5.68]
0.36 [0.16, 0.80]
0.38 [0.19, 0.78]
21
27
Total events
Heterogeneity: Tau² = 0.11; Chi² = 3.75, df = 3 (P = 0.29); I² = 20%
Test for overall effect: Z = 2.65 (P = 0.008)
Test for subgroup differences: Chi² = 0.05, df = 1 (P = 0.83), I² = 0%
0.05
0.2
1
5
20
Favors treatment Favors no treatment
CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; RCT = randomized controlled trial
Brachial Plexus Injury
One RCT50 and one cohort study152 provided data for brachial plexus injury (Table 17). The
RCT found no significant difference between groups (RR 0.15; 95% CI, 0.01 to 2.87, n = 1,000),
while the cohort study showed a significant difference favoring the treated group (RR 0.04; 95%
CI, 0 to 0.66, n = 389).
Clavicular Fracture
The same two studies50,152 reported clavicular fractures with no difference for the RCT 50 (RR
0.35; 95% CI, 0.01 to 8.45, n = 1,030), and a significant difference favoring the treated group in
the cohort study152 (RR 0.02; 95% CI, 0 to 0.22, n = 389; Table 17).
Birth Trauma
Three studies reported birth trauma.54,96,152 Birth trauma was defined as brachial plexus palsy
or clavicular, humeral, or skull fracture in one study.54 Brachial plexus injury, cranial nerve
palsy, and clavicular facture were components of birth trauma in one study.152 In the third study
81
birth trauma or injury included fractures and neurologic sequelae. One of the RCTs found no
incidents in either group;96 the second RCT54 showed no significant difference between groups
(RR 0.48; 95% CI, 0.12 to 1.90, n = 1,230; Figure 57). One cohort study showed a significant
difference favoring the treated group (RR 0.02; 95% CI, 0.00 to 0.11, n = 389) (Table 17).152
Overall, the strength of evidence was insufficient for this outcome (Table 18).
Figure 57. Effect of treatment on outcomes for offspring of women with GDM: birth trauma
Study or Subgroup
2.4.1 RCT
Garner 1997
Landon 2009
Subtotal (95% CI)
Treatment
No treatment
Events Total Events
Total Weight
0
3
149
476
625
Total events
3
Heterogeneity: Not applicable
Test for overall effect: Z = 1.05 (P = 0.29)
0
6
Risk Ratio
M-H, Random, 95% CI
150
455 100.0%
605 100.0%
Not estimable
0.48 [0.12, 1.90]
0.48 [0.12, 1.90]
16 100.0%
16 100.0%
0.02 [0.00, 0.11]
0.02 [0.00, 0.11]
Risk Ratio
M-H, Random, 95% CI
6
2.4.2 Cohort studies
Adams 1998
Subtotal (95% CI)
2
373
373
4
Total events
2
4
Heterogeneity: Not applicable
Test for overall effect: Z = 4.64 (P < 0.00001)
Test for subgroup differences: Chi² = 8.16, df = 1 (P = 0.004), I² = 87.7%
0.005
0.1
1
10
200
Favors treatment Favors no treatment
CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; RCT = randomized controlled trial
Hypoglycemia
Six studies provided data on hypoglycemia (Table 14).50,54,96,97,146,152 The pooled results from
four RCTs showed no significant difference between groups (RR 1.18; 95% CI, 0.92 to 1.52, n =
2,367) and no statistical heterogeneity (Figure 58). The two cohort studies showed different
results: one study showed no significant difference, while the second study showed a significant
difference favoring the treated group (overall RR 0.55; 95% CI, 0.10 to 2.97, n = 2,054). The
different results may be due in part to different definitions of hypoglycemia used across the
studies. Overall, the strength of evidence was low suggesting no difference between groups in
the incidence of hypoglycemia (Table 15).
82
Figure 58. Effect of treatment on outcomes for offspring of women with GDM: hypoglycemia
Study or Subgroup
2.7.1 RCT
Bonomo 2005
Crowther 2005
Garner 1997
Landon 2009
Subtotal (95% CI)
Treatment
No treatment
Total Weight
Events Total Events
5
35
21
62
150
506
149
381
1186
6
27
13
55
150
4.5%
524 25.9%
150 14.4%
357 55.3%
1181 100.0%
Risk Ratio
M-H, Random, 95% CI
Risk Ratio
M-H, Random, 95% CI
0.83 [0.26, 2.67]
1.34 [0.82, 2.18]
1.63 [0.85, 3.13]
1.06 [0.76, 1.47]
1.18 [0.92, 1.52]
101
123
Total events
Heterogeneity: Tau² = 0.00; Chi² = 1.96, df = 3 (P = 0.58); I² = 0%
Test for overall effect: Z = 1.33 (P = 0.18)
2.7.2 Cohort studies
Adams 1998
Langer 2005
Subtotal (95% CI)
26
67
373
1110
1483
0
100
16 25.2%
555 74.8%
571 100.0%
2.41 [0.15, 37.88]
0.34 [0.25, 0.45]
0.55 [0.10, 2.97]
100
93
Total events
Heterogeneity: Tau² = 0.97; Chi² = 1.97, df = 1 (P = 0.16); I² = 49%
Test for overall effect: Z = 0.69 (P = 0.49)
0.05
0.2
1
5
20
Favors treatment Favors no treatment
Test for subgroup differences: Chi² = 0.77, df = 1 (P = 0.38), I² = 0%
CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; RCT = randomized controlled trial
Hyperbilirubinemia
Four studies provided data on hyperbilirubinemia (Table 14).54,96,97,146 Three RCTs showed
no significant difference between groups54,96,97 (RR 0.79; 95% CI, 0.56 to 1.10, n = 1,467), while
one cohort study showed a significant difference favoring the treated group146 (RR 0.26; 95% CI,
0.18 to 0.37, n = 1,665; Figure 59).
Figure 59. Effect of treatment on outcomes for offspring of women with GDM: hyperbilirubinemia
Study or Subgroup
2.3.1 RCT
Bonomo 2005
Garner 1997
Landon 2009
Subtotal (95% CI)
Treatment
No treatment
Total Weight
Events Total Events
6
8
43
150
149
450
749
4
10
54
150
7.3%
150 13.9%
418 78.9%
718 100.0%
Risk Ratio
M-H, Random, 95% CI
Risk Ratio
M-H, Random, 95% CI
1.50 [0.43, 5.21]
0.81 [0.33, 1.98]
0.74 [0.51, 1.08]
0.79 [0.56, 1.10]
68
Total events
57
Heterogeneity: Tau² = 0.00; Chi² = 1.14, df = 2 (P = 0.57); I² = 0%
Test for overall effect: Z = 1.39 (P = 0.16)
2.3.2 Cohort studies
Langer 2005
Subtotal (95% CI)
40
1110
1110
78
555 100.0%
555 100.0%
0.26 [0.18, 0.37]
0.26 [0.18, 0.37]
78
40
Total events
Heterogeneity: Not applicable
Test for overall effect: Z = 7.26 (P < 0.00001)
Test for subgroup differences: Chi² = 19.56, df = 1 (P < 0.00001), I² = 94.9%
0.2
0.5
1
2
5
Favors treatment Favors no treatment
CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; RCT = randomized controlled trial
83
Mortality
Six studies provided data on perinatal deaths (Table 14).50,54,92,96,146,152 No significant
differences were found between groups for the three RCTs50,54,96 (RD 0; 95% CI, -0.01 to 0.01, n
= 2,287) or for the three cohort studies92,146,152 (RD 0; 95% CI, -0.01 to 0.01, n = 2,928; Figure
60). There was heterogeneity among the three RCTs with one study showing a significant
difference in favor of the treatment group.
Figure 60. Effect of treatment on outcomes for offspring of women with GDM: perinatal deaths
Study or Subgroup
2.1.1 RCT
Crowther 2005
Garner 1997
Landon 2009
Subtotal (95% CI)
Treatment
No treatment
Events Total Events
Total Weight
0
0
0
506
149
485
1140
5
0
0
524 31.7%
150 22.7%
473 45.6%
1147 100.0%
Risk Difference
M-H, Random, 95% CI
Risk Difference
M-H, Random, 95% CI
-0.01 [-0.02, -0.00]
0.00 [-0.01, 0.01]
0.00 [-0.00, 0.00]
-0.00 [-0.01, 0.01]
Total events
0
5
Heterogeneity: Tau² = 0.00; Chi² = 5.94, df = 2 (P = 0.05); I² = 66%
Test for overall effect: Z = 0.71 (P = 0.48)
2.1.2 Cohort studies
Adams 1998
Chou, 2010
Langer 2005
Subtotal (95% CI)
1
5
4
373
385
1110
1868
0
4
3
16
0.6%
489 20.4%
555 78.9%
1060 100.0%
0.00 [-0.08, 0.08]
0.00 [-0.01, 0.02]
-0.00 [-0.01, 0.01]
-0.00 [-0.01, 0.01]
Total events
10
7
Heterogeneity: Tau² = 0.00; Chi² = 0.82, df = 2 (P = 0.66); I² = 0%
Test for overall effect: Z = 0.13 (P = 0.89)
Test for subgroup differences: Chi² = 0.24, df = 1 (P = 0.62), I² = 0%
-0.05 -0.025 0 0.025 0.05
Favors treatment Favors no treatment
CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; RCT = randomized controlled trial
Respiratory Complications
Two RCTs50,54 reported on respiratory distress syndrome and showed no significant
difference between groups (RR 1.05; 95% CI, 0.48 to 2.28, n = 1,962; Table 17, Figure 61). One
cohort study146 reported respiratory complications and showed a significant difference favoring
the treated group (RR 0.16; 95% CI, 0.10 to 0.26, n = 1,665).
84
Figure 61. Effect of treatment on outcomes for offspring of women with GDM: respiratory
complications
Study or Subgroup
2.14.1 RCT
Crowther 2005
Landon 2009
Subtotal (95% CI)
Treatment
No treatment
Events Total Events
Total Weight
27
9
506
477
983
19
13
Risk Ratio
M-H, Random, 95% CI
524 57.6%
455 42.4%
979 100.0%
Risk Ratio
M-H, Random, 95% CI
1.47 [0.83, 2.61]
0.66 [0.29, 1.53]
1.05 [0.48, 2.28]
36
Total events
32
Heterogeneity: Tau² = 0.19; Chi² = 2.38, df = 1 (P = 0.12); I² = 58%
Test for overall effect: Z = 0.12 (P = 0.91)
2.14.2 Cohort (respiratory complication)
Langer 2005
Subtotal (95% CI)
22
1110
1110
67
555 100.0%
555 100.0%
0.16 [0.10, 0.26]
0.16 [0.10, 0.26]
22
67
Total events
Heterogeneity: Not applicable
Test for overall effect: Z = 7.52 (P < 0.00001)
Test for subgroup differences: Chi² = 16.02, df = 1 (P < 0.0001), I² = 93.8%
0.1 0.2
0.5
1
2
5 10
Favors treatment Favors no treatment
CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; RCT = randomized controlled trial
APGAR
One RCT50 and one cohort study95 compared APGAR scores at 1 minute (Table 17). Both
showed a significant difference favoring the treatment group, although the results were more
dramatic for the cohort study (RCT MD -0.30; 95% CI, -0.56 to -0.04, n = 83; cohort MD -1.00;
95% CI, -1.54 to -0.46, n = 126; Figure 56). Another cohort study92 reported the number of
infants with APGAR scores <7 at 1 minute and showed no difference between groups (RR 0.76,
95% CI, 0.47 to 1.25). Two RCTs97,98 and one cohort study95 compared APGAR scores at 5
minutes and no overall differences were found (Figure 62). There was substantial statistical
heterogeneity between the two RCTs with one RCT showing no difference and the second
showing a significant difference favoring the untreated group. The cohort study showed no
difference (n = 126). One study50 reported APGAR scores <7 at 5 minutes and found no
difference between groups (n = 1,030).
Figure 62. Effect of treatment on outcomes for offspring of women with GDM: APGAR scores, 5
minutes
Study or Subgroup
2.12.1 RCT
Bevier 1999
Bonomo 2005
Treatment
No treatment
Mean
SD Total Mean
SD Total
9
9.7
0.3
0.5
35
150
9 0.63
69
9
9.5
Mean Difference
IV, Random, 95% CI
0.4
0.5
48
150
0.00 [-0.15, 0.15]
0.20 [0.09, 0.31]
9 0.87
57
0.00 [-0.27, 0.27]
Mean Difference
IV, Random, 95% CI
2.12.2 Cohort studies
Fassett 2007
-0.2 -0.1
0
0.1
0.2
Favors treatment Favors no treatment
CI = confidence interval; GDM = gestational diabetes mellitus; IV = inverse variance; RCT = randomized controlled trial; SD =
standard deviation
85
Other Infant Outcomes
Single studies reported on elevated cord blood c-peptide level,54 preterm delivery,54 length,97
ponderal index,97 any serious perinatal complication,50 and abnormal fetal heart rate.98
Significant differences were found for ponderal index (MD -0.09; 95% CI, -0.16 to -0.02, n =
300) and any serious perinatal complication (RR 0.32; 95% CI, 0.14 to 0.73, n = 1,030). Both
results favored the treated group (Table 17).
Long Term
Type 2 Diabetes Mellitus
One small study reported 7 to 11 year followup and showed no significant difference in the
incidence of type 2 diabetes mellitus among the offspring (RR 1.88; 95% CI, 0.08 to 44.76, n =
89).96 The same study reported impaired glucose tolerance at 7-11 year followup.96 Overall no
difference was found (Table 17) (RR 5.63; 95% CI, 0.31 to 101.32, n = 89). The strength of
evidence for both type 2 diabetes mellitus and impaired glucose tolerance was considered
insufficient (Table 18).
BMI
One small study reported the incidence of BMI >95 percentile at 7 to 11 year followup and
showed no significant difference between groups (RR 1.58; 95% CI, 0.66 to 3.79, n = 85; Table
17).96 The original RCT96 showed no differences in mean birth weight or macrosomia
(birthweight >4,000 g and birthweight >4,500 g). A followup study9 reporting outcomes at 4 to 5
years following the initial RCT reported BMI >85 percentile and also found no difference
between groups (RR 1.19; 95% CI, 0.78 to 1.82, n = 199), despite a clear difference in
macrosomia rates between treatment and control group (5% vs. 22%, respectively). When the
two studies were pooled, the results showed no difference (RR 1.26; 95% CI, 0.86, 1.84, n = 284,
Table 17) and the strength of evidence was considered low (Table 18).
86
Table 17. Evidence summary for Key Question 4: infant outcomes
Outcome
Number of
Participants
2,643
Cohort
6
3,426
RCT
Cohort
RCT
1
2
5
299
647
2,670
Cohort
2
515
RCT
Cohort
RCT
Cohort
RCT
Cohort
RCT
Cohort
RCT
Cohort
RCT
Cohort
RCT
Cohort
RCT
Cohort
RCT (RDS)
Cohort
(complications)
RCT
Cohort
3
4
3
4
1
1
1
1
2
1
4
2
3
1
3
3
2
2,261
2,294
2,044
3,054
1,000
389
1,030
389
1,230
389
2,367
2,054
1,467
1,665
2,287
2,928
1,962
0.50 [0.35, 0.71]
Results not pooled due to
substantial heterogeneity
1.01 [0.33, 3.05]
0.29 [0.07, 1.25]
†
-120.81 [-163.40, -78.23]
Results not pooled due to
substantial heterogeneity
0.56 [0.45, 0.69]
0.43 [0.27, 0.70]
0.42 [0.23, 0.77]
0.38 [0.19, 0.78]
0.15 [0.01, 2.87]
0.04 [0.00, 0.66]
0.35 [0.01, 8.45]
0.02 [0.00, 0.22]
0.48 [0.12, 1.90]
0.02 [0.00, 0.11]
1.18 [0.92, 1.52]
0.55 [0.10, 2.97]
0.79 [0.56, 1.10]
0.26 [0.18, 0.37]
‡
-0.00 [-0.01, 0.01]
‡
-0.00 [-0.01, 0.01]
1.05 [0.48, 2.28]
1
1,665
1
1
83
126
RCT
2
383
Cohort
1
126
RCT
Birthweight >4,000 g
Birthweight >4,500 g
Birthweight
Large for gestational age
Shoulder dystocia
Brachial plexus injury
Clavicular fracture
Birth trauma
Hypoglycemia
Hyperbilirubinemia
Perinatal deaths
Respiratory complications
APGAR 1 min
APGAR 5 min
2
Number of
Studies
5
Source
Effect Estimate*
I
(%)
50
Treatment
86
Treatment
NA
69
2
Treatment
77
Favors
-
0
58
0
0
NA
NA
NA
NA
NA
NA
0
49
0
NA
66
0
58
Treatment
Treatment
Treatment
Treatment
Treatment
Treatment
Treatment
Treatment
-
0.16 [0.10, 0.26]
NA
Treatment
-0.30 [-0.56, -0.04]
-1.00 [-1.54, -0.46]
Results not pooled due to
substantial heterogeneity
0.00 [-0.27, 0.27]
NA
NA
Treatment
Treatment
87
77
-
NA
-
Table 17. Evidence summary for Key Question 4: infant outcomes (continued)
Outcome
Type 2 DM (long-term)
Impaired glucose
tolerance
2
RCT
Number of
Studies
1
Number of
Participants
89
1.88 [0.08, 44.76]
I
(%)
NA
RCT
1
89
5.63 [0.31, 101.32]
44
Source
Effect Estimate*
Favors
-
>95 percentile
1
85
1.58 [0.66, 3.79]
NA
>85 percentile
1
199
1.19 [0.78, 1.82]
NA
BMI (long-term)
Any BMI (2
2
284
1.26 [0.86, 1.84]
0
studies above
combined)
BMI = body mass index; DM = diabetes mellitus; NA = not applicable; RCT = randomized controlled trial; RDS = respiratory distress syndrome
*Risk ratios unless otherwise specified.
†Mean difference.
‡Risk difference.
88
Table 18. Strength of evidence for Key Question 4: maternal and infant outcomes
Outcome
Preeclampsia
Maternal weight gain
Birth injury
Source
Risk of
Bias
Consistency
Directness
Precision
3 RCTs
Low
Consistent
Direct
Imprecise
1 cohort
4 RCTs
2 cohorts
2 RCTs
High
Medium
High
Medium
Unknown
Inconsistent
consistent
Consistent
Direct
Direct
Direct
Direct
Imprecise
Imprecise
Imprecise
Imprecise
1 cohort
High
Unknown
Direct
Imprecise
3 RCTs
Medium
Consistent
Direct
Precise
4 cohorts
High
Consistent
Direct
Precise
4 RCTs
Medium
Consistent
Direct
Imprecise
2 cohorts
High
Inconsistent
Direct
Imprecise
5 RCTs
Medium
Consistent
Direct
Precise
6 cohorts
High
Inconsistent
Direct
Precise
Overall SOE
Comment
Moderate (favors
treatment)
Insufficient
Insufficient
Insufficient
Low
The evidence provides moderate
confidence that the estimate reflects the
true effect in favor of the treatment group.
There is insufficient evidence to draw
conclusions for this outcome
There is insufficient evidence to make a
conclusion for this outcome. There is a
difference in findings for the RCTs and
cohort studies; the number of events and
participants across all studies does not
allow for a conclusion.
Insufficient
(favors
treatment)
Moderate (favors
treatment)
Shoulder dystocia
Neonatal
hypoglycemia
Macrosomia >4,000 g
Long-term metabolic
outcomes: impaired
1 RCT
Medium
Unknown
Direct
glucose tolerance
Long-term metabolic
outcomes: type 2
1 RCT
Medium
Unknown
Direct
diabetes mellitus
Long-term metabolic
outcomes: BMI
2 RCTs
Medium
Consistent
Direct
th
(assessed as >85
th
and >95 percentile)
BMI = body mass index; RCT = randomized controlled trial; SOE = strength of evidence
89
Low (favors
treatment)
Low (no
difference)
Insufficient
Moderate (favors
treatment)
Low (favors
treatment)
The evidence provides moderate
confidence that the estimate reflects the
true effect in favor of the treatment group.
The evidence provides low confidence
that there is no difference between
groups.
The evidence provides moderate
confidence that the estimate reflects the
true effect in favor of the treatment group.
Imprecise
Insufficient
There is insufficient evidence to draw
conclusions for this outcome.
Imprecise
Insufficient
There is insufficient evidence to draw
conclusions for this outcome.
Imprecise
Low (no
difference)
The evidence provides low confidence
that there is no difference between
groups.
Key Question 5. What are the harms of treating GDM and do they vary by
diagnostic approach?
Description of Included Studies
Five of the studies included in Key Question 4 also provided data for Key Question
5.50,54,95,97,98 The studies are described in Appendix D. All studies compared diet modification,
glucose monitoring and insulin as needed with standard care. Four of the studies were
randomized controlled trials,50,54,97,98 while one study was a retrospective cohort.95 The studies
were published between 1999 and 2009 (median year 2005). Two studies had two associated
publications reporting initial and longer term outcomes.163,164 Three studies were from the United
States,54,95,98 and one each from Italy97 and Australia.50 The screening test used in most studies
was OGCT with a 100 g OGTT assessed using CC criteria, except for the study from Australia
that used a OGCT with a 75 g OGTT. Timing of diagnosis of GDM occurred at or after 24
weeks’ gestation. Among these studies a variety of glucose threshold criteria were used for
inclusion, varying from 50 g screen positive with nondiagnostic oral glucose tolerance tests to
WHO criteria for a diagnosis of GDM. The 2 largest RCTs by Crowther et al. and Landon et
al.50,54 used different glucose thresholds for entry in their trials: WHO and CC criteria with a
fasting glucose <95 mg/dL (5.3 mmol/L), respectively. The mean fasting glucose levels at study
entry were similar between these 2 trials.
Methodological Quality of Included Studies
Among the four RCTs, one had low50 and three54,97,98 had unclear risk of bias. The trials that
were unclear most commonly did not report detailed methods for sequence generation and
allocation concealment. Two trials54,97 were unclear with respect to blinding of participants. One
trial had incomplete reporting of outcome data.98 The cohort study was high quality (7/9
points);95 the primary limitation was not controlling for potential confounders.
Key Points
•
There was no evidence for some of the outcomes stipulated in the protocol including
costs and resource allocation. There was limited evidence for harms and the evidence
related to anxiety and depression. There was also limited evidence for number of prenatal
visits and admissions to NICU. Results are detailed below.
Maternal Outcomes
•
A single RCT assessed depression and anxiety at 6 weeks after study entry and 3 months
postpartum. There was no significant difference between groups in anxiety at either time
point, although there were significantly lower rates of depression in the treatment group
at 3 months postpartum.
Outcomes in the Offspring
•
Four RCTs reported small for gestational age and found no significant difference.
Health System Outcomes
•
Three RCTs and one cohort study provided data on admission to NICU and showed no
significant differences overall. One trial was an outlier as it showed a significant
90
•
•
•
difference favoring the no treatment group. This difference may be attributable to sitespecific policies and procedures.
Two RCTs reported on the number of prenatal visits and generally found significantly
more visits among the treatment groups. The same two studies showed a lower incidence
of patients requiring insulin therapy in the untreated groups.
There was inconsistency across studies in terms of induction of labor with no difference
found for the 2 RCTs overall and a significant difference favoring the treatment group
among the one cohort study included. Among the RCTs, one showed a significant
difference with fewer cases in the group receiving no treatment,50 while the other study
showed no difference.54 In the RCT that showed more inductions of labor in the treatment
group, no recommendations were provided regarding obstetrical care, thus replicating
usual clinical care of women with GDM. In the other RCT, antenatal surveillance was
reserved for standard obstetrical indications.
No differences between groups were found for cesarean section (5 RCTs, 6 cohorts) or
unplanned cesarean section (1 RCT, 1 cohort).
Detailed Synthesis
Maternal Outcomes
Depression and Anxiety
One RCT assessed depression and anxiety at 6 weeks after study entry and 3 months
postpartum.50 Depression was assessed using the Edinburgh Postnatal Depression Score and
anxiety was assessed using the Spielberger State-Trait Anxiety Inventory. There was no
significant difference between groups in anxiety at either time point, although there were
significantly lower rates of depression in the treatment group 3 months postpartum (Table 19).
The authors of the primary study note that the findings regarding anxiety and depression should
be interpreted cautiously because they were based on a subgroup of the women included in the
trial.
Fetal/Neonatal/Child Outcomes
Small for Gestational Age (SGA)
SGA was reported in four RCTs50,54,97,98 and overall no significant difference was found
between groups (RR 1.10; 95% CI, 0.81 to 1.48; Table 19, Figure 63).
Figure 63. Effect of treatment on adverse effects for infants of mothers with GDM: SGA
Study or Subgroup
Bevier 1999
Bonomo 2005
Crowther 2005
Landon 2009
Total (95% CI)
Treatment
No Treatment
Total Weight
Events Total Events
3
13
33
36
35
150
506
477
1168
2
9
38
29
Risk Ratio
M-H, Random, 95% CI
48
150
524
455
3.0%
13.2%
43.9%
39.9%
2.06 [0.36, 11.67]
1.44 [0.64, 3.28]
0.90 [0.57, 1.41]
1.18 [0.74, 1.90]
1177
100.0%
1.10 [0.81, 1.48]
78
85
Total events
Heterogeneity: Tau² = 0.00; Chi² = 1.79, df = 3 (P = 0.62); I² = 0%
Test for overall effect: Z = 0.60 (P = 0.55)
Risk Ratio
M-H, Random, 95% CI
0.1 0.2
0.5
1
2
5
10
Favors Treatment Favors No Treatment
CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; SGA = small for gestational age
91
Society/Health Care System Outcomes
Admission to NICU
Three RCTs50,54,97 and one cohort study95 provided data on admission to the NICU (Table
19). Among the three RCTs there was no significant difference overall (RR 0.96; 95% CI, 0.67
to 1.37, n = 2,262; Table 19, Figure 64), although there was substantial statistical heterogeneity
(I2 = 61%). One study was an outlier as it showed a significant effect favoring the untreated
group (RR 1.15; 95% CI, 1.05 to 126, n = 1,030). Removing this study from the analysis reduced
the heterogeneity to 0% and the result remained non-significant. One cohort study also showed
no significant difference in NICU admissions (RR 0.66; 95% CI, 0.19 to 2.35, n = 126).95
Figure 64. Effect of treatment on adverse effects for infants of mothers with GDM: NICU
admissions
Study or Subgroup
3.3.1 RCT
Bonomo 2005
Crowther 2005
Landon 2009
Subtotal (95% CI)
Treatment
No Treatment
Total Weight
Events Total Events
5
357
43
150
506
477
1133
7
321
53
Risk Ratio
M-H, Random, 95% CI
150
8.6%
524 56.4%
455 35.0%
1129 100.0%
Risk Ratio
M-H, Random, 95% CI
0.71 [0.23, 2.20]
1.15 [1.05, 1.26]
0.77 [0.53, 1.13]
0.96 [0.67, 1.37]
405
381
Total events
Heterogeneity: Tau² = 0.06; Chi² = 5.16, df = 2 (P = 0.08); I² = 61%
Test for overall effect: Z = 0.21 (P = 0.83)
3.3.2 Cohort studies
Fassett 2007
Subtotal (95% CI)
4
69
69
4
Total events
Heterogeneity: Not applicable
Test for overall effect: Z = 0.64 (P = 0.52)
5
57 100.0%
57 100.0%
0.66 [0.19, 2.35]
0.66 [0.19, 2.35]
5
Test for subgroup differences: Chi² = 0.31, df = 1 (P = 0.58), I² = 0%
0.2
0.5
1
2
5
Favors Treatment Favors No Treatment
CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; NICU = neonatal intensive care unit;
RCT = randomized controlled trial
Number of Prenatal Visits
Two RCTs reported on the number of prenatal visits.50,54 Landon et al.54 reported an average
of seven prenatal visits in the treatment group versus five in the control group (p<0.001).
Crowther et al.50 reported the median number of antenatal clinic visits and physician clinical
visits after enrolment. The intervention group had fewer antenatal clinic visits (median 5.0 [interquartile range (IQR) 1-7] vs. 5.2 [IQR 3-7], p<0.001); whereas they had more physician clinic
visits (median 3 [IQR 1-7] vs. 0 [IQR 0-2]). The intervention group also had significantly more
visits with a dietician (92 percent vs. 10 percent, p<0.001) and with a diabetes educator (94
percent vs. 11 percent, p<0.001).
Induction of Labor
[Note: This outcome was presented under Key Question 4. It is also presented here as it may
be considered a harm in terms of more resource use and more invasive management.] Three
studies provided data on induction of labor50,54,146 but results differed significantly across the
studies (Table 19). Two RCTs showed no significant difference overall (RR 1.16, 95% CI 0.91
to 1.49, n = 1,931), although there was important statistical heterogeneity between studies (I2 =
92
69%). One RCT showed a significant difference favoring no treatment,50 while the other study
showed no difference (Figure 65).54 Different study protocols may account for the heterogeneity
of results between studies. In the study that showed more inductions of labor in the treatment
group, no recommendations were provided regarding obstetrical care, thus replicating usual
clinical care of women with GDM. In the other study, antenatal surveillance was reserved for
standard obstetrical indications. In contrast the one cohort study showed a significant difference
with fewer inductions in the treatment group (RR 0.63, 95% CI 0.55 to 0.72, n = 1,665).146
Baseline differences in the study populations and regional practices may have accounted for the
different results between studies. Further, the comparison group in the cohort study was women
who presented late for obstetrical care which confounds the relationship between induction and
GDM treatment. Furthermore, the cohort study protocol was to deliver these women within one
week of GDM diagnosis so the outcome of induction was substantially confounded by different
delivery protocols between treatment and nontreatment groups.
Figure 65. Effect of treatment on outcomes of women with GDM: induction of labor
Study or Subgroup
1.6.1 RCT
Crowther 2005
Landon 2009
Subtotal (95% CI)
Treatment
No treatment
Events Total Events
Total Weight
189
130
490
476
966
150
122
Risk Ratio
M-H, Random, 95% CI
510 52.8%
455 47.2%
965 100.0%
Risk Ratio
M-H, Random, 95% CI
1.31 [1.10, 1.56]
1.02 [0.82, 1.26]
1.16 [0.91, 1.49]
Total events
319
272
Heterogeneity: Tau² = 0.02; Chi² = 3.27, df = 1 (P = 0.07); I² = 69%
Test for overall effect: Z = 1.20 (P = 0.23)
1.6.2 Cohort Studies
Langer 2005
Subtotal (95% CI)
303
1110
1110
242
555 100.0%
555 100.0%
0.63 [0.55, 0.72]
0.63 [0.55, 0.72]
Total events
303
242
Heterogeneity: Not applicable
Test for overall effect: Z = 6.81 (P < 0.00001)
Test for subgroup differences: Chi² = 18.61, df = 1 (P < 0.0001), I² = 94.6%
0.5
0.7
1
1.5
2
Favors treatment Favors no treatment
CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; RCT = randomized controlled trial
Cesarean Delivery
[Note: This outcome was presented under Key Question 4. It is also presented here as it may
be considered a harm in terms of more resource use and more invasive management.] All studies
provided data on cesarean delivery (Table 19).50,54,92,95-98,146,148,152,160 There was no significant
difference in the pooled estimates for the RCTs (RR 0.90, 95% CI 0.79 to 1.01, n = 2,613) or for
the cohort studies (RR 1.09, 95% CI 0.90 to 1.31, n = 3,110; Figure 66). The results were
statistically homogeneous across all studies. One RCT50 and one cohort study95 reported
emergency cesarean deliveries and found no difference (RCT, RR 0.81, 95% CI 0.62 to 1.05, n =
1,000; cohort, RR 0.83, 95% CI 0.33 to 2.06, n = 126).
93
Figure 66. Effect of treatment on outcomes of women with GDM: cesarean delivery
Study or Subgroup
1.1.1 RCT
Bevier 1999
Bonomo 2005
Crowther 2005
Garner 1997
Landon 2009
Subtotal (95% CI)
Treatment
No treatment
Events Total Events
Total Weight
5
42
152
30
128
35
150
490
149
476
1300
12
44
164
28
154
Risk Ratio
M-H, Random, 95% CI
48
1.6%
150 11.3%
510 43.1%
150
6.7%
455 37.3%
1313 100.0%
Risk Ratio
M-H, Random, 95% CI
0.57 [0.22, 1.47]
0.95 [0.67, 1.36]
0.96 [0.80, 1.16]
1.08 [0.68, 1.71]
0.79 [0.65, 0.97]
0.90 [0.79, 1.01]
Total events
357
402
Heterogeneity: Tau² = 0.00; Chi² = 3.68, df = 4 (P = 0.45); I² = 0%
Test for overall effect: Z = 1.81 (P = 0.07)
1.1.2 Cohort studies
Adams 1998
Bonomo 1997
Chou, 2010
Fassett 2007
Langer 2005
Naylor, 1996
Subtotal (95% CI)
99
7
40
21
258
48
373
26
233
69
1110
143
1954
4
26
32
19
132
34
16
4.5%
88
6.4%
325 15.0%
57 11.5%
555 43.0%
115 19.6%
1156 100.0%
1.06 [0.45, 2.52]
0.91 [0.45, 1.85]
1.74 [1.13, 2.69]
0.91 [0.55, 1.52]
0.98 [0.81, 1.17]
1.14 [0.79, 1.63]
1.09 [0.90, 1.31]
Total events
473
247
Heterogeneity: Tau² = 0.01; Chi² = 6.47, df = 5 (P = 0.26); I² = 23%
Test for overall effect: Z = 0.88 (P = 0.38)
Test for subgroup differences: Chi² = 2.93, df = 1 (P = 0.09), I² = 65.9%
0.2
0.5
1
2
5
Favors treatment Favors no treatment
CI = confidence interval; GDM = gestational diabetes mellitus; M-H = Mantel-Haenszel; RCT = randomized controlled trial
Table 19. Evidence summary for Key Question 5
Outcome
Number of
Studies
Number of
Participants
Small for gestational age
4
2,345
1.10 [0.81, 1.48]
(RCTs)
Anxiety (6 weeks, RCT)
682
-0.30 [-0.88, 0.28]
1
Anxiety (3 months, RCT)
573
-0.20 [-0.83, 0.43]
1
Depression (3 months, RCT)
568
0.50 [0.31, 0.79]
1
Admission to NICU
RCT 3
2,262
0.96 [0.67, 1.37]
Cohort 1
126
0.66 [0.19, 2.35]
Induction of labor
RCT 2
1,931
1.16 [0.91, 1.49]
Cohort 1
1,665
0.63 [0.55, 0.72]
Cesarean section
RCT 5
2,613
0.90 [0.79, 1.01]
Cohort 6
3,110
1.09 [0.90, 1.31]
Unplanned cesarean section
RCT 1
1000
0.81 [0.62, 1.05]
Cohort 1
126
0.83 [0.33, 2.06]
NA = not applicable; NICU = neonatal intensive care unit; RCT = randomized controlled trial
*Risk ratio
94
I2
(%)
Effect Estimate*
Favors
0
-
NA
NA
NA
Treatment
61
NA
-
69
NA
Treatment
0
23
-
NA
NA
-
Discussion
Key Findings and Discussion
Key findings are presented by Key Question in the sections that follow. A summary of the
results for all Key Questions is provided in Table 24 at the end of the Discussion.
Key Question 1
Fifty-one studies provided data for Key Question 1 that sought to examine the test
characteristics and prevalence of current screening and diagnostic tests for gestational diabetes
mellitus (GDM). The lack of a “gold standard” to confirm a diagnosis of GDM limits the ability
to compare the results of studies that used different diagnostic criteria. Different criteria result in
different rates of prevalence for GDM, regardless of similarities across study settings and patient
characteristics.
The methodological quality of the studies was assessed using the QUADAS-2 tool. There
were several concerns about the quality and applicability of the studies that addressed Key
Question 1. First, there is concern about the risk for partial verification bias, which can occur
when not all of the patients are verified by the reference standard. In 25 percent of the studies,
women who were below the threshold for further screening on the oral glucose challenge test
(OGCT) did not undergo an oral glucose tolerance test (OGTT) to confirm a diagnosis of GDM.
For 35 percent of studies, it was unclear risk whether all patients underwent both tests. Another
concern relates to the risk of diagnostic review bias in which the interpretation of the results of
the reference standard may have been influenced by the knowledge of the results of the index
test. Eighty percent of studies were assessed as high or unclear risk for this domain. A third
concern relates to the domain of patient selection and the possibility of spectrum bias; 82 percent
of studies were assessed as having high or unclear concerns for applicability. This was primarily
because the studies were conducted in developing countries and used the World Health
Organization (WHO) criteria to diagnose GDM.
The evidence showed that the 50 g OGCT with the 130 mg/dL cutpoint had higher sensitivity
when compared with the 140 mg/dL cutpoint; however, specificity was lower (99 vs. 85 and 77
vs. 86, respectively). Both thresholds have high negative predictive values (NPV), but variable
positive predictive values (PPV) across a range of GDM prevalence. When the risk of a missing
a diagnosis is considered high, screening tests with high NPV are preferred at the expense of
PPV. However, if the harm of an incorrect diagnostic is high, screening tests with high PPV are
preferred at the expense of NPV. The Toronto Trihospital study found evidence to support the
use of the lower screening cutpoint for higher risk patients, and the higher screening cutpoint for
lower risk patients.15 While graded cutpoints for the diagnosis and treatment of dyslipidemia and
osteoporosis based on risk factors are used in routine clinical practice, this approach is not
widely accepted for the screening of GDM.
The large randomized controlled trials (RCTs) that showed some treatment benefits
employed a two-step approach to screening and diagnosis for GDM.50,54 The practical efficiency
of a two-step approach may be improved by setting a high threshold value on the screening test,
above which no further confirmation testing is required for diagnosis. One study provides
support for this approach by demonstrating that a threshold of 200 mg/dL on a 50 g OGCT
95
resulted in 100 percent positive and negative predictive values for diagnosing GDM by
Carpenter and Coustan (CC) and National Diabetes Data Group (NDDG) criteria.104
Only three studies included women who were in their first trimester of pregnancy and they
used different diagnostic criteria. Therefore, no conclusions can be made about the test
characteristics of screening tests for this group of women.
There are limited data to support the use of glycated hemoglobin (HbA1c) as a screening test.
A study conducted in the United Arab Emirates using an HbA1c value of 5.5 percent or more
lacked specificity (21 percent) despite good sensitivity (82 percent).113 A study conducted in
Turkey showed that an HbA1c cutoff of 7.2 percent or more had 64 percent sensitivity and
specificity.74 HbA1c does not perform as well as the 50 g OGCT as a screening test for GDM.
However, when HbA1c is markedly elevated this supports a possible diagnosis of overt diabetes
discovered in pregnancy. Since 2011-2012 the American Diabetes Association (ADA) has
endorsed the use of an HbA1c of 6.5 percent or more as diagnostic of diabetes in nonpregnant
women.36 Studies of HbA1c with trimester specific cutoffs to determine the value at which overt
diabetes should be diagnosed in pregnancy are needed.
The sensitivity for fasting plasma glucose (FPG) of 85 mg/dL as a screening test for GDM is
similar to that for the 50 OGCT with a threshold of 140 mg/dL; however, specificity is lower. As
the threshold for fasting glucose is increased specificity is gained at the expense of sensitivity.
The use of fasting glucose as a screening test for GDM has several clinical advantages over the
OGCT when the tests are performed at or after 24 weeks’ gestation. FPG has the advantage of
greater reproducibility than post glucose load testing.165 In addition, it is easier to administer to
women who cannot tolerate the glucose drink. Furthermore, fasting glucose has been positively
associated with clinical outcomes of concern for GDM.142,166 However, a recent report from the
Hyperglycemia and Adverse Pregnancy Outcome Study (HAPO) data found that a fasting
glucose of 92 mg/dL did not diagnose GDM in women from Hong Kong and Bangkok as
frequently as it did in other populations, and the elevated post glucose load glucose
measurements were more frequently diagnostic of an International Association of the Diabetes in
Pregnancy Study Groups (IADPSG) diagnosis of GDM in women from Hong Kong and
Bangkok.6
Our review did not identify compelling evidence for or against risk factor-based screening.
Naylor et al. used the Toronto Trihospital study data to develop a risk scoring system for GDM
screening using variable glucose thresholds based on age, body mass index (BMI), and race.
When applied to a validation group, sensitivity and specificity were similar to universal
screening.167
There are limited data to draw conclusions about the effectiveness of the different options for
diagnostic testing for GDM. Four studies compared the 75 g and 100 g load tests, but they were
conducted in different countries and used different criteria or thresholds. However, because both
the 75 g and 100 g load tests are positively linked with outcomes142,166 and the 75 g test is less
time consuming, the adoption of the 75 g glucose load may be warranted even if thresholds
continue to be debated3,142
The IADPSG has proposed the elimination of a screening test in favor of proceeding directly
to a diagnostic test for GDM. We identified only one study124 that compared the IADPSG criteria
with the Australasian Diabetes in Pregnancy Society (ADIPS) that used a two-step strategy.
Sensitivity was 82 percent (95% CI, 74 to 88) and specificity was 94 percent (95% CI, 93 to 96).
96
Prevalence and Predictive Values
The prevalence of GDM varied across studies and the diagnostic criteria used. Factors
contributing to the variability included differences in study setting (i.e., country), screening
practices (e.g., universal vs. selective), and population characteristics (e.g., race/ethnicity, age,
BMI).
The predictive value of a screening or diagnostic test is determined by the test’s sensitivity
and specificity and by the prevalence of GDM. Table 20 presents a series of scenarios that
demonstrate the changes in PPV and NPV for three levels of prevalence (7 percent, 15 percent,
and 25 percent).6 Separate tables are presented for different screening and diagnostic criteria.
The higher the prevalence of GDM, the higher the PPV, or the more likely a positive result is
able to predict the presence of GDM. When the prevalence of GDM is low, the PPV is also low,
even when the test has high sensitivity and specificity. Generally the NPV (negative result rules
out GDM) is very high—98 percent or better at a GDM prevalence of 7 percent.
Table 20. Relationship between predictive values and prevalence for different screening tests
Positive
Negative Predictive
Predictive Value
Value
7%
31%
99%
50 g OGCT ≥140 mg/dL by CC/ADA
15%
52%
97%
(2000-2010)
Sensitivity=85%; Specificity=86%
25%
67%
95%
7%
24%
100%
50 g OGCT ≥130 mg/dL by CC/ADA
15%
43%
100%
(2000-2010)
Sensitivity=99%; Specificity=77%
25%
59%
100%
7%
27%
99%
50 g OGCT ≥140 mg/dL by NDDG
15%
47%
97%
Sensitivity=85%; Specificity=83%
25%
63%
94%
7%
16%
99%
50 g OGCT ≥130 mg/dL by NDDG
15%
31%
97%
Sensitivity = 88%; Specificity = 66%
(median)
25%
46%
94%
7%
29%
99%
50 g OGCT ≥140 mg/dL by ADA 75 g
15%
49%
98%
Sensitivity=88%; Specificity=84% (median)
25%
65%
95%
7%
24%
98%
50 g OGCT ≥140 mg/dL by WHO
15%
42%
95%
Sensitivity=78%; Specificity=81% (median)
25%
58%
92%
7%
12%
98%
FPG (≥85 mg/dL) by CC/ADA (2000-2010)
15%
24%
96%
Sensitivity=87%; Specificity=52%
25%
38%
92%
7%
21%
98%
Risk factor screening by various criteria
15%
38%
96%
Sensitivity=84%; Specificity=72% (median)
25%
54%
93%
TADA = American Diabetes Association; CC = Carpenter-Coustan; FPG = fasting plasma glucose;
NDDG = National Diabetes Data Group; OGCT = oral glucose challenge test; WHO =World Health Organization
Screening Test
Prevalence
Key Question 2
Only two retrospective cohort studies were relevant to Key Question 2 which asked about the
direct benefits and harms of screening for GDM. One retrospective cohort study (n=1,000)
conducted in Thailand showed a significantly greater incidence of cesarean deliveries in the
screened group. A survey of a subset of participants (n=93) in a large prospective cohort study
involving 116,678 nurses aged 25-42 years in the United States found the incidence of
macrosomia (infant weight ≥ 4.3 kg) was the same in the screened and unscreened groups (7
percent each group).
97
There were no RCTs available to answer questions about screening. There is a paucity of
evidence on the impact of screening women for GDM on health outcomes. The comparison for
this question was women who had and had not undergone screening. Since screening is now
commonplace it may be unlikely to identify studies or cohorts where this comparison is feasible.
Key Question 3
Thirty-eight studies provided data for Key Question 3 that sought to examine health
outcomes for women who meet various criteria for GDM and do not receive treatment. The
majority of data came from cohort studies or the untreated groups from RCTs.
A wide variety of diagnostic criteria and thresholds were compared across the studies. The
most common groups reported and compared were GDM diagnosed by CC criteria, no GDM by
any criteria (normal), impaired glucose tolerance defined as one abnormal glucose value (OAV),
and false positive (positive OGCT, negative OGTT).). Only single studies contributed data for
many of the comparisons and outcomes, which does not allow for definitive conclusions.
Further, results that showed no statistically significant differences cannot be interpreted as
equivalence between groups nor do they rule out potential differences. A summary of the
strength of evidence for key outcomes is provided in Table 21 and Table 22.
For maternal outcomes among the studies that compared groups as described above, women
without GDM and those testing false positive showed fewer cases of preeclampsia than those
meeting CC criteria; the strength of evidence was considered low for these two comparisons. No
differences in preeclampsia were found for other comparisons, although evidence was based on
few studies per comparison and strength of evidence was rated insufficient.
Fewer cases of cesarean section were found among women without GDM compared with
women meeting criteria for CC GDM, CC, 1 abnormal OGTT, CC false positives, NDDG false
positives, NDDG 1 abnormal oral glucose tolerance test, WHO IGT, IADPSG impaired fasting
glucose (IFG), and IADPSG impaired glucose tolerance (IGT) IFG. There were fewer cases of
cesarean section among false positives compared with women meeting criteria for CC GDM. For
12 other comparisons, there were no differences in rates of cesarean delivery.
For maternal hypertension, significant differences were found for eight of 16 comparisons;
many comparisons were based on single studies. No GDM groups showed lower incidence of
maternal hypertension when compared with CC GDM, CC, 1 abnormal OGTT, IADPSG IFG,
IADPSG double impaired glucose tolerance (IGT-2), and IADPSG IGT IFG. Other comparisons
showing significant differences were CC GDM versus false positives (lower incidence for false
positives), IADPSG IGT versus IGT IFG (lower incidence for IGT), and IADPSG IFG versus
IGT IFG (lower incidence for IFG).
Based on single studies, no differences were observed for maternal birth trauma for three
comparisons. For maternal weight gain (less weight gain considered beneficial), significant
differences were found for three of 12 comparisons: IADPSG IGT versus no GDM (favored
IGT), IADPSG IFG versus no GDM (favored IFG), IADPSG IGT-2 versus no GDM (favored
IGT-2). All comparisons were based on single studies and the strength of evidence was
insufficient. For maternal mortality/morbidity, single studies contributed to three comparisons
and no differences were found except for fewer cases among patient groups with no GDM
compared with IADPSG GDM. No studies provided data on long-term maternal outcomes, such
as type 2 diabetes mellitus, obesity and hypertension.
98
Table 21. Summary of strength of evidence for the association between different glucose levels
and maternal outcomes (Key Question 3)
Number of
Studies
Outcome
Preeclampsia
Strength of
Evidence
CC GDM vs. no GDM
3 cohorts
Low
CC GDM vs.
false positive
2 cohorts
Low
Summary
Statistically significant difference with
fewer cases in the patient groups with
no GDM (RR 1.50, 95% CI 1.07, 2.11)
Statistically significant difference with
fewer cases in the false-positive
group (RR 1.51, 95% CI 1.17, 1.93)
NDDG false positive
2 cohorts
Insufficient
vs. no GDM
NDDG, 1 abnormal
1 cohort
Insufficient
OGTT vs. no GDM
WHO IGT vs. no GDM
3 cohorts
Insufficient
CC, 1 abnormal OGTT
1 cohort
Insufficient
vs. no GDM
WHO IGT vs. no GDM
1 cohort
Insufficient
IADPSG IGT vs.
1 cohort
Insufficient
no GDM
IADPSG IFG vs.
1 cohort
Insufficient
no GDM
IADPSG IGT-2 vs.
1 cohort
Insufficient
no GDM
IADPSG IGT IFG vs.
Maternal weight
1 cohort
Insufficient
no GDM
gain
IADPSG IGT vs. IFG
1 cohort
Insufficient
IADPSG IGT vs. IGT-2 1 cohort
Insufficient
IADPSG IGT vs.
1 cohort
Insufficient
IGT IFG
IADPSG IFG vs. IGT-2 1 cohort
Insufficient
IADPSG IFG vs.
1 cohort
Insufficient
IGT IFG
IADPSG IGT-2 vs.
1 cohort
Insufficient
IGT IFG
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; IFG = impaired fasting glucose; IGT =
impaired glucose tolerance; IGT-2 = double impaired glucose tolerance; IADPSG = International Association of Diabetes and
Pregnancy Study Groups; NDDG = National Diabetes Data Group; OGTT = oral glucose tolerance test; RR = risk ratio; WHO =
World Health Organization
The most commonly reported outcome for the offspring was macrosomia >4,000 g. Six of 11
comparisons showed a significant difference: there were fewer cases in the group without GDM
compared with CC GDM, CC 1 abnormal OGTT, NDDG GDM (unrecognized), NDDG false
positives, and WHO IGT. Fewer cases were found for women with false-positive results
compared with CC GDM. The strength of evidence for these findings was low to insufficient.
Data for macrosomia >4,500 g was available for four comparisons and showed significant
differences in two cases: patient groups with no GDM had fewer cases compared with women
with CC GDM and with unrecognized NDDG GDM. The strength of evidence was low and
insufficient, respectively.
For shoulder dystocia, significant differences were found for seven of 17 comparisons; all but
one comparison was based on single studies (insufficient strength of evidence). Patient groups
with no GDM showed lower incidence of shoulder dystocia when compared with CC GDM (5
studies; low strength of evidence), NDDG GDM (unrecognized), NDDG false positive, WHO
IGT, IADPSG IFG, and IADPSG IGT IFG. The other significant difference showed lower
incidence among the false-positive group compared with CC 1 abnormal OGTT. For fetal birth
99
trauma or injury, four studies compared CC GDM, NDDG GDM and WHO IGT with patient
groups without GDM (insufficient strength of evidence). No differences were observed except
for NDDG GDM which favored the group with no GDM.
Only one difference was found for neonatal hypoglycemia with fewer cases among patient
groups without GDM compared with those meeting CC criteria; strength of evidence was
insufficient. There were 16 comparisons for hyperbilirubinemia; the majority were based on
single studies. Three comparisons showed significant differences between groups: patient groups
with no GDM had fewer cases compared with CC false positive, IADPSG IGT, and IADPSG
IGT-2, respectively. No differences were found for fetal morbidity/mortality for any of eight
comparisons which may be attributable to small numbers of events within some comparisons.
Moreover, comparisons were based on single studies.
Based on a single study, significant differences were found in prevalence of childhood
obesity for CC GDM versus no GDM (lower prevalence for no GDM) and CC GDM versus false
positives (lower prevalence for false positives). This was consistent for both childhood obesity
>85th percentile as well as >95th percentile. However, this study was unable to control for
maternal weight or BMI which are established predictors of childhood obesity. No differences,
based on the same single study, were found for the other four comparisons within >85th or >95th
percentiles. No other studies provided data on long-term outcomes, including type 2 diabetes
mellitus and transgenerational GDM.
In summary, different thresholds of glucose intolerance impact maternal and neonatal
outcomes of varying clinical importance. While many studies have attempted to measure the
association between various criteria for GDM and pregnancy outcomes in the absence of
treatment, the ability of a study or pooled analysis to find a statistically significant difference in
pregnancy outcomes appears more dependent on study design, in particular the size of the study
or pooled analysis, rather than the criteria used for diagnosing GDM. This is not surprising given
the strong support found for a continuous positive relationship between glucose and a variety of
pregnancy outcomes. Moreover, two methodologically strong studies met the inclusion criteria
for this question but could not be pooled with the other studies because they examined glucose
thresholds as a continuous outcome.3,91 These studies demonstrated a continuous positive
relationship between increasing glucose levels and the incidence of primary cesarean section,
and macrosomia. One of these studies also found significantly fewer cases of preeclampsia,
cesarean section, shoulder dystocia and/or birth injury, clinical neonatal hypoglycemia, and
hyperbilirubinemia for women with no GDM compared with those meeting IADPSG criteria.3
The clinical significance of absolute differences in event rates requires contemplation by
decision makers even though statistical significance was reached at the strictest diagnostic
glucose thresholds for some outcomes.
This question focused on outcomes for women who did not receive treatment for GDM.
While women with untreated GDM have a variety of poorer outcomes than women without
GDM, it cannot be assumed that treatment of GDM reverses all the short- and long-term poor
outcomes observed in women with untreated GDM. Some of the reasons for the poorer outcomes
in women that have untreated GDM may not be modifiable, such as the influences of genetic
makeup. The strength of evidence was insufficient for most outcomes and comparisons in this
question due to high risk of bias (observational studies), inconsistency across studies, and/or
imprecise results.
100
Table 22. Summary of strength of evidence for the association between different glucose levels
and neonatal/infant outcomes (Key Question 3)
Number
of
Studies
Outcome
Strength
of
Evidence
Statistically significant difference
with fewer cases in the patient
group with no GDM (RR 1.61,
95% CI 1.35, 1.92)
Statistically significant difference
with fewer cases in the falsepositive group (RR 1.36, 95% CI
1.10, 1.68)
No statistically significant
difference (RR 0.99, 95% CI
0.92, 1.07)
Statistically significant difference
with fewer cases in the patient
group with no GDM (RR 1.44,
95% CI 1.13, 1.82)
No statistically significant
difference (RR 1.02, 95% CI
0.85, 1.24)
CC GDM vs. no GDM
10
cohorts
Low
CC GDM vs. false positive
5 cohorts
Low
CC GDM vs. 1 abnormal
OGTT
3 cohorts
Low
CC 1 abnormal OGTT vs. no
GDM
7 cohorts
Low
CC false positive vs. no
GDM
5 cohorts
Low
3 cohorts
Insufficient
-
1 cohort
Insufficient
-
Macrosomia >4,000 g
CC 1 abnormal OGTT vs.
false positive
NDDG GDM (unrecognized)
vs. no GDM
Macrosomia >4,500 g
Summary
NDDG false positive vs. no
GDM
4 cohorts
Low
WHO GDM vs. no GDM
WHO IGT vs. no GDM
IADPSG GDM vs. no GDM
1 cohort
1 cohort
2 cohorts
Insufficient
Insufficient
Insufficient
CC GDM vs. no GDM
3 cohorts
Low
CC GDM vs. false positive
CC false positive vs. no
GDM
NDDG GDM (unrecognized)
vs. no GDM
2 cohorts
Insufficient
Statistically significant difference
with fewer cases in the patient
group with no GDM (RR 1.44,
95% CI 1.10, 1.89)
Statistically significant difference
with fewer cases in the patient
group with no GDM (RR 2.52,
95% CI 1.65, 3.84)
-
2 cohorts
Insufficient
-
1 cohort
Insufficient
-
101
Table 22. Summary of strength of evidence for the association between different glucose levels
and neonatal/infant outcomes (Key Question 3) (continued)
Outcome
Comparison
CC GDM vs. no GDM
Number
of
Studies
5 cohorts
Strength
of
Evidence
Low
Summary
Statistically significant difference
with fewer cases in the patient
group with no GDM (RR 2.86,
95% CI 1.81, 4.51)
-
CC GDM vs. false positive
1 cohort
Insufficient
CC 1 abnormal OGTT vs. no
1 cohort
Insufficient
GDM
CC 1 abnormal OGTT vs.
1 cohort
Insufficient
false positive
NDDG GDM (unrecognized)
1 cohort
Insufficient
vs. no GDM
NDDG false positive vs. no
1 cohort
Insufficient
GDM
Shoulder Dystocia
WHO IGT vs. no GDM
1 cohort
Insufficient
IADPSG IGT vs. no GDM
1 cohort
Insufficient
IADPSG IFG vs. no GDM
1 cohort
Insufficient
IADPSG IGT-2 vs. no GDM
1 cohort
Insufficient
IADPSG IGT IFG vs. no
1 cohort
Insufficient
GDM
IADPSG IGT vs. IFG
1 cohort
Insufficient
IADPSG IGT vs. IGT-2
1 cohort
Insufficient
IADPSG IGT vs. IGT IFG
1 cohort
Insufficient
IADPSG IFG vs. IGT-2
1 cohort
Insufficient
IADPSG IFG vs. IGT IFG
1 cohort
Insufficient
IADPSG IGT-2 vs. IGT IFG
1 cohort
Insufficient
CC GDM vs. no GDM
3 cohorts Insufficient
CC GDM vs. 1 abnormal
1 cohort
Insufficient
OGTT
CC 1 abnormal OGTT vs. no
4 cohorts Insufficient
Neonatal
GDM
Hypoglycemia
NDDG GDM vs. no GDM
1 cohort
Insufficient
NDDG false positive vs. no
1 cohort
Insufficient
GDM
WHO IGT vs. no GDM
3 cohorts Insufficient
CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; IFG = impaired fasting glucose; IGT =
impaired glucose tolerance; IGT-2 = double impaired glucose tolerance; IADPSG = International Association of Diabetes and
Pregnancy Study Groups; NDDG = National Diabetes Data Group; OGTT = oral glucose tolerance test; RR = risk ratio; WHO =
World Health Organization
Key Question 4
Eleven studies provided data for Key Question 4 to assess the impact of treatment for GDM
on health outcomes of mothers and offspring. All studies compared diet modification, glucose
monitoring, and insulin as needed with standard care. The strength of evidence for key outcomes
is summarized in Table 23.
There was moderate evidence showing a significant difference for preeclampsia with fewer
cases in the treated group. There was inconsistency across studies in terms of differences in
maternal weight gain and the strength of evidence was considered insufficient. There were no
data on long-term outcomes among women including type 2 diabetes mellitus, obesity, and
hypertension.
102
In terms of infant outcomes, there was insufficient evidence to make a conclusion for birth
injury. This was driven by lack of precision in the effect estimates and inconsistency across
studies: there was no difference for RCTs but a significant difference favoring treatment in the
one cohort study. The incidence of shoulder dystocia was significantly lower in the treated
groups, and this finding was consistent for the 3 RCTs and 4 cohort studies. Overall, the
evidence for shoulder dystocia was considered moderate showing a difference in favor of the
treated group. For neonatal hypoglycemia, the strength of evidence was low suggesting no
difference between groups. There was moderate evidence showing significantly lower incidence
of macrosomia among the treated groups.
Only one study provided data on long-term metabolic outcomes among the offspring at 7 to
11 year followup. The strength of evidence was insufficient to reach a conclusion. For both
outcomes―impaired glucose tolerance and type 2 diabetes mellitus―no differences were found
between groups although the estimates were imprecise. No differences were observed in single
studies that assessed BMI >95 (7-11 year followup) and BMI >85 percentile (5-7 year followup).
Overall, pooled results showed no difference in offspring BMI and the strength of evidence was
considered low.
In summary, there was moderate evidence showing differences in preeclampsia and shoulder
dystocia with fewer cases among women (and offspring) who were treated compared with those
not receiving treatment. There was also moderate evidence showing significantly fewer cases of
macrosomia (>4,000 g) among offspring of women who received treatment for GDM. The
results were driven by the two largest RCTs, the Maternal Fetal Medicine Unit (MFMU)54 and
the Australian Carbohydrate Intolerance in Pregnancy Study (ACHOIS),50 which had unclear and
low risk of bias, respectively. There was little evidence showing differences in other key
maternal and infant outcomes between groups. One potential explanation is that for the most part
the study populations included women whose glucose intolerance was less marked, as those
whose glucose intolerance was more pronounced would not have been entered into a trial where
they may be assigned to a group receiving no treatment. For outcomes where results were
inconsistent between studies, different study glucose threshold entry criteria did not explain the
variation. For some outcomes, particularly the long-term outcomes, the strength of evidence was
insufficient or low suggesting that further research may change the results and increase our
confidence in the results. Moreover, for some outcomes events were rare and the studies may not
have had the power to detect clinically important differences between groups; therefore, findings
of no significant difference should not be interpreted as equivalence between groups.
103
Table 23. Summary of strength of evidence for benefits of treatment (Key Question 4)
Outcome
Number of
Studies
Strength of
Evidence
Preeclampsia
3 RCTs,
1 cohort
Moderate
Maternal weight
gain
4 RCTs,
2 cohorts
Insufficient
Birth injury
2 RCTs,
1 cohort
Insufficient
Shoulder
dystocia
3 RCTs,
4 cohorts
Moderate
Neonatal
hypoglycemia
4 RCTs,
2 cohorts
Low
Macrosomia
(>4,000 g)
5 RCTs,
6 cohorts
Moderate
1 RCT
Insufficient
Maternal outcomes
Infant outcomes
Long-term
metabolic outcomes
in offspring
Impaired
glucose
tolerance
Type 2 diabetes
mellitus
Summary
Significant difference in favor of
treatment for RCTs (RR 0.62, 95% CI
0.43, 0.89). No difference observed for
cohort study.
Results not pooled for RCTs due to
substantial heterogeneity. No
difference for cohort studies (MD -1.04,
95% CI -2.89, 0.81).
No difference for RCTs (RR 0.48, 95%
CI 0.12, 1.90). Significant difference
favoring treatment for cohort study (RR
0.02, 95% CI 0.00, 0.22).
Significant difference in favor of
treatment for RCTs (RR 0.42, 95% CI
0.23, 0.77) and cohort studies (RR
0.38, 95% CI 0.19, 0.78).
No difference for RCTs (RR 1.18, 95%
CI 0.92, 1.52) or cohort studies (RR
0.55, 95% CI 0.10, 2.97).
Significant difference in favor of
treatment for RCTs (RR 0.50, 95% CI
0.35, 0.71). Results not pooled for
cohort studies due to substantial
heterogeneity.
No difference between groups (RR
5.63, 95% CI 0.31, 101.32).
No difference between groups (RR
1.88, 95% CI 0.08, 44.76).
No difference between groups (RR
BMI
2 RCTs
Low
1.26, 95% CI 0.86, 1.84)
BMI = body mass index; CI = confidence interval; MD = mean difference; RCT = randomized controlled trial; RR = risk ratio
1 RCT
Insufficient
Key Question 5
Five studies provided data for Key Question 5 on the harms associated with treatment of
GDM. There was no evidence for some of the outcomes stipulated in the protocol including costs
and resource allocation.
Four of the studies provided data on the incidence of infants that were small for gestational
age and showed no significant difference between groups. This finding may have resulted from
inadequate power to detect differences due to a small number of events; therefore, the finding of
no significant difference should not be interpreted as equivalence between groups. Four studies
provided data on admission to the neonatal intensive care unit (NICU) and showed no significant
differences overall. One study was an outlier as it showed significantly fewer NICU admissions
in the group receiving no treatment. This difference may be attributable to site-specific policies
and procedures. Two studies reported on the number of prenatal visits and generally found
significantly more visits among the treatment groups.
Two RCTs showed no significant difference overall in the rate of induction of labor,
although there was important statistical heterogeneity between studies. One RCT showed
significantly more inductions of labor in the treatment group50 while the other study did not.54
Different study protocols may account for the heterogeneity of results between studies. In the
104
first study, that showed more inductions of labor in the treatment group, no recommendations
were provided regarding obstetrical care. In the later study, antenatal surveillance was reserved
for standard obstetrical indications. Based on the studies included in Key Question 4, there was
no difference in Cesarean section between treatment and non treatment GDM (5 RCTs and 6
cohort studies).
A single study assessed depression and anxiety at 6 weeks after study entry and 3 months
postpartum using the Spielberger State-Trait Anxiety Inventory and the Edinburgh Postnatal
Depression Score, respectively. There was no significant difference between groups in anxiety at
either time point, although there were significantly lower rates of depression in the treatment
group at 3 months postpartum. These results should be interpreted cautiously because the
assessment of depression and anxiety was conducted in a subgroup of the larger RCT. Maternal
stress in pregnancy has been associated with poor metabolic consequences in offspring.168 Other
research found that women with GDM compared with glucose tolerant women had a higher level
of anxiety at time of the first assessment; however, before delivery these differences in anxiety
scores did not persist.169
Findings in Relationship to What Is Already Known
This review provides evidence that treating GDM reduces some poor maternal and neonatal
outcomes. The recent randomized trial published in 2009 by the MFMU54 reinforces the findings
of the earlier ACHOIS trial which was published in 2005 50 and included in an earlier version of
this review.53 Both trials showed that treating GDM to targets of 5.3 or 5.5 mmol/L fasting and
6.7 or 7.0 mmol/L 2 hours post-meal reduced neonatal birthweight, large for gestational age,
macrosomia, shoulder dystocia, and preeclampsia without a reduction in neonatal hypoglycemia
or hyperbilirubinemia/jaundice requiring phototherapy, or an increase in small for gestational
age. In contrast to the ACHOIS trial, MFMU demonstrated a reduced cesarean section rate in the
GDM treatment group. The failure of ACHOIS to find a lower cesarean section rate despite
reduced neonatal birthweight and macrosomia may have been the result of differing obstetrical
practices or the different populations studied (e.g., the inclusion of some women with more
marked glucose intolerance in ACHOIS as reflected by the increased prevalence of insulin use;
more black and Hispanic women in the MFMU study). Differences may have also resulted due to
study design: in ACHOIS, participants did not receive specific recommendations regarding
obstetrical care, thus replicating obstetrical care for women with GDM. In the MFMU study,
antenatal surveillance was reserved for standard obstetrical indications. Our findings of the effect
of treatment of GDM is similar to a systematic review and meta-analysis published in 2010 by
Horvath et al.170 that included two older RCTs of GDM that were not included in our analysis
because we restricted our inclusion criteria to studies published after 1995.
The Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) Study Cooperative Research
Group 3 confirmed findings of the earlier Toronto Trihospital study 142 in a large international
sample of women with a simpler 75 g OGTT showing a continuous positive association between
maternal glucose and increased birthweight, as well as fetal hyperinsulinemia (HAPO only), at
levels below diagnostic thresholds for GDM that existed at the time of the study. However, no
clear glucose thresholds were found for fetal overgrowth or a variety of other maternal and
neonatal outcomes. Subsequently, the IADPSG developed diagnostic thresholds for GDM based
on a consensus of expert opinion of what was considered to be the most important outcomes and
the degree of acceptable risk for these outcomes. The thresholds chosen by the IADPSG were
derived from the HAPO data to identify women with a higher risk (adjusted odds ratio 1.75) of
105
large for gestational age, elevated c-peptide, high neonatal body fat compared with the mean
maternal glucose values of the HAPO study. The glucose threshold chosen by the IADPSG
represents differing levels of risk for other outcomes. Specifically the IADPSG thresholds
represent a 1.4 (1.26-1.56) risk for pregnancy induced hypertension and a 1.3 (1.07,1.58) risk for
shoulder dystocia.
Neither recent RCT was designed to determine diagnostic thresholds for GDM or therapeutic
glucose targets. However, it is noteworthy that therapeutic glucose targets for both ACHOIS and
MFMU were above the proposed diagnostic criteria of the IADPSG (fasting 5.5 mmol/L (99
mg/dL) and 5.3 mmol/L (95 mg/dL and 2 hour post-meal of 7.0 mmol/L (126 mg/dL and 6.7
mmol/L 120 mg/dL), respectively). A change in diagnostic criteria without addressing
management thresholds could contribute to clinical confusion. If diagnostic thresholds for GDM
below the treatment targets of the large RCTs are endorsed, this could ethically obstruct the
possibility of future RCTs to compare different treatment targets above such diagnostic
thresholds.
It has been hypothesized that treatment of GDM may reduce future poor metabolic outcomes
for children born to mothers with GDM. If true, the potential for long-term gain is important
from a clinical and public health perspective and may justify the “costs” of screening and
treating women for GDM. However, the followup of offspring from two RCTs 50,96 and a HAPO
cohort in Belfast 171 currently fail to support this hypothesis. This may be explained in part due to
insufficient length of followup or inadequate numbers of events.
The HAPO study showed that maternal weight and glucose predict large for gestational age.
However, body mass index was the better predictor of large for gestational age than glucose until
glucose thresholds higher than the diagnostic thresholds set by the IADPSG were reached.172,173
Most cases of large for gestational age occur in neonates of mothers with normal glycemia. A
large observational study found that the upper quartile of maternal BMI accounted for 23 percent
of macrosomia, while GDM was responsible for only 3.8 percent.174 The ongoing obesity
epidemic in the United States warrants careful consideration of a diagnostic approach for GDM
that incorporates maternal BMI. This would require the development and validation of a risk
model that incorporates maternal BMI as well as other modifiable risk factors. Such a model
could facilitate the identification of women at high risk of adverse pregnancy outcomes and
minimize exposure of lower risk women to unnecessary interventions.
Applicability
There are several issues that may limit the applicability of the evidence presented in this
review to the U.S. population, and these vary slightly by Key Question. All of the Key Questions
asked about the effects of screening and treatment before and after 24 weeks’ gestation. The vast
majority of included studies screened women after 24 weeks’ gestation, therefore the results are
not applicable to screening and treatment earlier in gestation.
For Key Question 1 on the test properties of screening and diagnostic tests, comparisons
involving the WHO criteria are less applicable to the U.S. setting as these criteria are not used in
North America. There were insufficient data from the included studies to assess the performance
of screening or diagnostic tests for specific patient characteristics (e.g., BMI, race/ethnicity).
Therefore it is unclear whether the evidence applies to specific subpopulations of women.
For Key Question 2, limited evidence was identified because the comparison of interest was
women who had not undergone screening. As screening is routine in prenatal care in the United
States, the evidence (or limited evidence) is likely not helpful for U.S. decisionmaking and a
106
refinement of this question may be appropriate to reflect current practices and outstanding
questions.
With respect to Key Question 3, all studies or groups included for analysis involved women
who had not received treatment for GDM. It cannot be assumed that the same association and
outcomes would be observed in clinical practice where standard care is to screen for and treat
GDM. The untreated women may differ from the general population in ways that are related to
the reasons for which they did not seek or receive early prenatal care (e.g., socioeconomic
status). That is, the reasons that they did not receive treatment for GDM are varied; some reasons
such as late presentation for obstetrical care may confound the observed association with health
outcomes. Attempts were made to control for these factors in some studies by including a group
of women without GDM with similar known confounderse.g.,146 or by adjusting for known
confounders in the analysis. The adjusted estimates did not change the overall pooled results in
the majority of cases and did not change the overall conclusions.
The majority of the studies for Key Questions 4 and 5 pertaining to the benefits and harms of
treatment for GDM were conducted in North America or Australia. Most of the North American
studies were inclusive of mixed racial populations and are likely applicable to the general U.S.
population. Even though the Australian RCT50 population had more white women with a lower
BMI than the U.S. RCT (MFMU54), this should not affect applicability of most of their findings
because these patient characteristics would be factors associated with lower risk of poor
outcomes. Differences in physician or hospital billing structures between the United States and
Australia may have accounted for the discrepant findings with respect to NICU admissions and
as a result limit the applicability of this finding in the United States. Among the studies included
in Key Questions 4 and 5, a variety of glucose threshold criteria were used for inclusion, varying
from 50 g screen positive with nondiagnostic oral glucose tolerance tests to women who met
National Diabetes Data Group criteria for a diagnosis of GDM. The two large RCTs used
different glucose thresholds for entry in their trials: WHO and CC criteria with a fasting glucose
<95 mg/dL (5.3 mmol/L), respectively.50,54 The mean glucose levels at study entry were similar
between these two RCTs, which may reflect a reluctance to assign women with more marked
glucose intolerance to a group receiving no treatment. The results may not be applicable to
women with higher levels of glucose intolerance.
Limitations of the Evidence Base
There is sparse evidence to clarify issues regarding the timing of screening and treatment for
GDM (i.e., before and after 24 weeks’ gestation). Earlier screening will help identify overt type 2
diabetes mellitus and distinguish this from GDM. This has important implications for clinical
management and ongoing followup beyond pregnancy. Previously unrecognized type 2 diabetes
mellitus diagnosed in pregnancy should be excluded from the diagnosis of GDM because this
condition has the highest perinatal mortality rate of all classes of glucose intolerance in
pregnancy.175 This distinction within research studies will provide more targeted evidence to
assist obstetrical care providers to risk stratify obstetrical care and glycemic management of
patients with overt type 2 diabetes mellitus diagnosed in pregnancy and those with less
pronounced pregnancy-induced glucose intolerance. This will also facilitate better comparability
across future studies. There were few data available on long-term outcomes. Furthermore, the
studies included in this review do not provide evidence of a direct link between short-term and
long-term outcomes (e.g., macrosomia and childhood obesity).
107
Care provider knowledge of the glucose screening and diagnostic results may have
introduced a bias if their subsequent treatment of women differed depending on the results. This
was of particular concern for Key Question 3. For Key Question 3, which assessed how the
various criteria for GDM influenced pregnancy outcomes, many of the statistically significant
differences seemed to be driven by the size of the study or pooled analysis, i.e., statistically
significant differences could be found if the sample were sufficiently large. However, these
differences may not be clinically important. The absolute differences in event rates between
different glucose thresholds need careful consideration by decisionmakers even though
statistically significant differences were found. Another key limitation with the evidence for Key
Question 3 is that the studies included were cohort studies, many of which did not control for
potential confounders. Therefore, any associations between glucose thresholds and outcomes
should be interpreted with caution.
Given that the large landmark studies91,142 show a continuous relationship between glucose
and maternal and neonatal outcomes, the lack of clear thresholds contributes to the uncertainty
regarding a diagnostic threshold for GDM. While there is controversy about where to set lower
limits for diagnostic criteria, the identification of overt diabetes in pregnancy is imperative if this
diagnosis has not occurred prior to pregnancy. Overt diabetes first identified in pregnancy should
be distinguished from GDM in order to gain a better understanding of the true risk of GDM to
pregnancy outcomes. Unfortunately there is no literature to guide diagnostic criteria for a
diagnosis of overt diabetes in pregnancy.
There were several methodological concerns for this evidence base. For example, risk of
spectrum bias and partial verification bias (Key Question 1); different definitions or methods of
assessing key outcomes (e.g., clinical vs. biochemical neonatal hypoglycemia and
hyperbilirubinemia) (Key Questions 3 and 4); and, lack of blinding of treatment arms in some
studies (Key Questions 4 and 5).
Future Research
Several important gaps in the current literature exist:
• The adoption of a consistent comparator for diagnosis of GDM, such as the 75 g OGTT,
would facilitate comparisons across studies even if different diagnostic thresholds are
used.
• Further analysis of the HAPO data could help answer some outstanding questions. For
example, further analysis could better define absolute differences in rare event rates. This
evidence could be used to inform discussions about the clinical importance of absolute
differences in event rates at thresholds other than those of the IADPSG. Such analyses
should include adjustment for important confounders such as maternal BMI.
• Further analysis of the HAPO data examining center to center differences in glucose
outcome relationships would be helpful in determining the usefulness of FPG as a
screening test for GDM.
• Research is needed to clarify issues regarding earlier screening and treatment, particularly
as they relate to the diagnosis, treatment, and long-term outcomes of pregestational
(overt) diabetes.
• FPG is a screening test that requires further research, given that the reproducibility of
fasting glucose measurement is superior to post glucose load measurements.165
• Further study of the long-term metabolic impact on offspring whose mothers have been
treated for GDM is warranted. In addition, data on the influences of GDM treatment on
108
•
•
•
•
•
•
•
•
long-term breastfeeding success have not been studied. The association of breastfeeding
with reduced poor metabolic outcomes in offspring of GDM has been found to have a
dose dependent response with duration of breastfeeding.176
Well-conducted prospective cohort studies of the “real world” impact of GDM treatment
on care utilization are needed.
Research is needed to help determine the glucose thresholds and treatment targets at
which GDM treatment benefits outweigh the risks of treatment and no treatment. This
will best be achieved through well-conducted, large RCTs that randomize women with
GDM to different glucose treatment targets.
While this review did not identify evidence of substantial harms to treatment, the
populations considered were mostly women whose GDM was controlled without
medication. There is a risk for more precautionary management of women diagnosed
with GDM who are perceived by clinicians to be at greater risk, such as those managed
with insulin, which may result in unnecessary interventions (e.g., cesarean section).177
Therefore, RCTs investigating the care of women diagnosed with GDM, including fetal
surveillance protocols, are needed to guide obstetrical investigations and management of
GDM. Further, RCTs comparing delivery management for GDM with and without
insulin or medical management are needed to provide clinicians guidance on appropriate
timing and management of delivery in women with GDM to avoid unnecessary
intervention in “the real world” driven by health care provider apprehension.
Long-term studies that evaluate the potential increased or decreased resource utilization
associated with the implementation of diabetes prevention strategies after a diagnosis of
GDM are required.
Studies to assess the long-term impact that a label of GDM may have for future
pregnancy planning, future pregnancy management, and future insurability are required.
The increased prevalence of type 2 diabetes mellitus in women of reproductive age merits
consideration of preconception screening for overt diabetes in women at risk of type 2
diabetes. In addition to poor maternal and neonatal outcomes associated with overt
diabetes in pregnancy, there is potential for benefit of preconception care.
Long-term benefits and harms need to be evaluated among different treatment modalities
for GDM (e.g., diet, exercise, insulin, oral glucose lowering medications, and/or
combinations of these).
Since 2011-2012 the ADA has endorsed the use of an HbA1c of 6.5 percent or more as
diagnostic of diabetes in nonpregnant women.36 Studies of HbA1c with trimester-specific
cutoffs to determine the value at which overt diabetes should be diagnosed in pregnancy
are needed.
Limitations of the Review
This review followed rigorous methodological standards which were detailed a priori. The
limitations of the review to fully answer the Key Questions are largely due to the nature and
limitations of the existing evidence.
There are several limitations that need to be discussed regarding systematic reviews in
general. First, there is a possibility of publication bias. The impact of publication bias on the
results of diagnostic test accuracy reviews (Key Question 1) is not well understood nor have the
tools to investigate publication bias in these reviews been developed. For the remaining Key
Questions we may be missing unpublished and/or negative therapy studies, and may be
109
overestimating the benefits of certain approaches. However, we conducted a comprehensive and
systematic search of the published literature for potentially relevant studies. Search strategies
included combinations of subject headings and free text words. These searches were
supplemented by handsearching for gray literature (i.e., unpublished or difficult to find studies).
Despite these efforts, we recognize that we may have missed some studies.
There is also a possibility of study selection bias. However, we employed at least two
independent reviewers and feel confident that the studies that were excluded from this report
were done so for consistent and appropriate reasons. Our search was comprehensive, so it is
unlikely that there are many studies in press or publication that were missed.
Cost analysis of different screening and diagnostic approaches was not addressed in this
review.
Conclusions
There was limited evidence regarding the test characteristics of current screening and
diagnostic strategies for GDM. Lack of an agreed upon gold standard for diagnosis of GDM
creates challenges for assessing the accuracy of tests and comparing across studies. The 50 g
OGCT with a glucose threshold of 130 mg/dL versus 140 mg/dL improves sensitivity and
reduces specificity (10 studies). Both thresholds have high NPV, but variable PPV across a range
of GDM prevalence. There was limited evidence for the screening of GDM diagnosed less than
24 weeks’ gestation (3 studies). Single studies compared the diagnostic characteristics of
different pairs of diagnostic criteria in the same population. The use of fasting glucose (≥85
mg/dL) as a screen for GDM may be a practical alternative because of similar test characteristics
to the OGCT particularly in women who cannot tolerate any form of oral glucose load.
Evidence supports benefits of treating GDM with little evidence of short-term harm.
Specifically, treatment of GDM results in lower incidence of preeclampsia, macrosomia, and
large for gestational age infants. Current research does not demonstrate a treatment effect of
GDM on clinical neonatal hypoglycemia or future poor metabolic outcomes of the offspring.
RCTs of GDM treatment show limited harm related to treating GDM, other than an increased
demand for services. There is a risk for more precautionary management of women diagnosed
with GDM who are perceived by clinicians to be at greater risk, such as those managed with
insulin, which may result in unnecessary interventions (e.g., cesarean section); however, this
review found limited data for these outcomes and further research on the care of women
diagnosed with GDM (e.g., fetal surveillance protocols) is warranted.
What remains less clear is what the lower limit diagnostic thresholds for GDM should be.
Given the continuous association between glucose and a variety of outcomes, decisions should
be made in light of what outcomes that are altered by treatment are most important and what
level of increased risk is acceptable. A dichotomous view of GDM may no longer be appropriate,
given evidence of a continuous relationship between maternal blood glucose and pregnancy
outcomes. An alternative approach would be to define different glucose thresholds based on
maternal risk for poor pregnancy outcomes.
Further study is needed regarding the long-term metabolic impact on offspring of mothers
receiving GDM treatment; the “real world” impact of GDM treatment on care utilization outside
of structured research trials; and, the impact of the timing of screening for GDM, particularly
before 24 weeks’ gestation and in the first trimester of pregnancy. Early screening could help
identify pregestational (i.e., overt) diabetes. Research is urgently required to determine the best
110
way to diagnose and manage overt diabetes in pregnancy, particularly in an era of increasing
rates of obesity and diabetes in the U.S. population.
111
Table 24. Summary of Evidence for all Key Questions
Key Question
Number and Quality
of Studies
Limitations/
Consistency
Applicability
•
•
KQ1. What are the
sensitivities,
specificities,
reliabilities, and
yields of current
screening tests
for GDM? (A) After
24 weeks’
gestation? (B)
During the first
trimester and up
to 24 weeks’
gestation?
A) After 24 wk
gestation
51 prospective studies
Fair to good quality
Limitations: Lack of an
agreed upon gold standard
for diagnosis of GDM creates
challenges for assessing the
accuracy of tests and
comparing across studies.
GDM was confirmed using
criteria developed by CC,
ADA, NDDG, and WHO.
There were sparse data
comparing overall
approaches for diagnosis
and screening, e.g., one-step
vs. two-step, selective vs.
universal.
Consistency: Across studies,
numerous tests and
thresholds were examined.
Screening tests included the
50 g OGCT, FPG risk factorbased screening, and other
less common tests such as
HbA1c, serum fructosamine.
•
Prevalence of GDM
varied across studies and
diagnostic criteria used.
Results need to be
interpreted in the context
of prevalence.
Comparisons involving
WHO criteria are less
applicable to the North
American setting
because these criteria
are not used in North
America.
•
•
•
•
112
Summary of Findings
Prevalence varied across studies and diagnostic
criteria: ADA 2000-2010 (75 g) 2.0 to 19%
(range), CC 3.6 to 38%, NDDG 1.4 to 50%, WHO
2 to 24.5%.
9 studies examined a 50 g OGCT with a cutoff
value of ≥140 mg/dL; GDM was confirmed using
CC criteria. Results: sensitivity 85%, specificity
86%, prevalence 3.8 to 31.9%, PPV 18 to 27%
(prevalence <10), PPV 32 to 83% (prevalence
≥10), NPV median 98%.
6 studies examined a 50 g OGCT (≥130 mg/dL);
GDM was confirmed using CC criteria. Results:
sensitivity 99%, specificity 77%, prevalence 4.3
to 29.5%, PPV 11 to 31% (prevalence <10), PPV
31 to 62% (prevalence ≥10), NPV median 100%.
1 study examined a 50 g OGCT (≥200 mg/dL);
GDM was confirmed using CC criteria.
Sensitivity, specificity, PPV, and NPV were all
100%. Prevalence was 6.4%.
7 studies examined a 50 g OGCT (≥140 mg/dL);
GDM was confirmed using NDDG criteria.
Results: sensitivity 85%, specificity 83%,
prevalence 1.4 to 45.8%, PPV 12 to 39%
(prevalence <10), PPV 57% (prevalence ≥10),
NPV median 99%.
3 studies examined a 50 g OGCT (≥130 mg/dL);
GDM was confirmed using NDDG criteria.
Results: sensitivity 67 to 90% (range), specificity
47 to 84%, prevalence 16.7 to 35.3%, PPV 20 to
75%, NPV 86 to 95%.
3 studies examined a 50 g OGCT (different
thresholds); GDM was confirmed using ADA
2000-2010 (75 g) criteria. Prevalence was 1.6 to
4.1 (range). Results: sensitivity 86 to 97%
(range), specificity 79 to 87%, PPV 7 to 20%,
NPV 99 to 100%.
Table 24. Summary of Evidence for all Key Questions (continued)
Key Question
Number and Quality
of Studies
Limitations/
Consistency
Applicability
•
•
KQ1. What are the
sensitivities,
specificities,
reliabilities, and
yields of current
screening tests
for GDM? (A) After
24 weeks’
gestation? (B)
During the first
trimester and up
to 24 weeks’
gestation?
A) After 24 wk
gestation
51 prospective studies
Fair to good quality
•
(continued)
•
(continued)
•
113
Summary of Findings
3 studies examined a 50 g OGCT (≥140 mg/dL);
GDM was confirmed using WHO criteria. Results:
sensitivity 43 to 85%, specificity 73 to 94%,
prevalence 3.7 to 15.7%, PPV 18 to 20%
(prevalence <10), PPV 58% (prevalence ≥10),
NPV median 99%.
7 studies examined FPG at different thresholds;
GDM was confirmed using CC criteria. Results:
at ≥85 mg/dL sensitivity 87%, specificity 52%; at
≥90 mg/dL sensitivity 77%, specificity 76%; at
≥92 mg/dL sensitivity 76%, specificity 92%; at
≥95 mg/dL sensitivity 54%, specificity 93%. At
≥85 mg/dL prevalence 1.4 to 34.53 (range). PPV
10% (prevalence <10) and 23 to 59%
(prevalence ≥10). Median NPV 93%.
8 studies examined risk factor-based screening
but were not pooled. Studies used different
criteria to confirm GDM. Results: sensitivity 48 to
95% (range), specificity 22 to 94%, prevalence
1.7 to 16.9%, PPV 5 to 19% (prevalence <10),
PPV 20% (prevalence ≥10), NPV median 99%.
1 study compared IADPSG vs. ADIPS 2 step
(reference) to diagnose GDM. Results: sensitivity
82%, specificity 94%, prevalence 13.0%, PPV
61%, NPV 98%.
4 studies compared 75 g and 100 g load tests to
diagnose GDM. Prevalence ranged from 1.4 to
50%. Results were not pooled: sensitivity 18 to
100%, specificity 86 to 100%, PPV 12 to 100%,
NPV 62 to 100%.
Table 24. Summary of Evidence for all Key Questions (continued)
Key Question
KQ1. What are the
sensitivities,
specificities,
reliabilities, and
yields of current
screening tests
for GDM? (A) After
24 weeks’
gestation? (B)
During the first
trimester and up
to 24 weeks’
gestation?
Number and Quality
of Studies
(B) During the first
trimester and up to
24 wk gestation
3 prospective cohort
studies
Limitations/
Consistency
Limitations: Only 3 studies of
women before 24 wks
gestation; therefore, no
conclusions can be made for
test characteristics in early
pregnancy.
Applicability
•
•
Evidence too limited to
judge applicability.
•
Consistency: Not applicable
(not enough studies
addressing the same
question to judge
consistency).
(continued)
KQ2: What is the
direct evidence on
the benefits and
harms of
screening women
(before and after
24 weeks’
gestation) for
GDM to reduce
maternal, fetal,
and infant
morbidity and
mortality?
Limitations: No RCTs
available to answer this
question.
2 retrospective cohort
studies
Fair and good quality
Consistency: Not applicable
(not enough studies
addressing the same
question to judge
consistency).
The comparison for this
question was women
who had and had not
undergone screening.
Since screening is now
commonplace it may be
unlikely to identify studies
or cohorts where this
comparison is feasible.
114
•
•
Summary of Findings
1 study examined the 50 g OGCT at 10 wks and
confirmed GDM using JSOG criteria (75 g).
Results: sensitivity 88%, specificity 79%,
prevalence 1.6%, PPV 7%, NPV 100%.
1 study examined 50 g OGCT at 20 wks and
confirmed GDM using ADA (2000-2010) 100 g
criteria. Results: sensitivity 56%, specificity 94%,
prevalence 3.6%, PPV 24%, NPV 98%.
st
nd
1 study compared 1 and 2 trimester results
using 3 screening tests (OGCT at ≥130 mg/dL,
FPG, HbA1c); GDM confirmed using JSOG
st
criteria. Results (OGCT) 1 trimester: prevalence
1.9%, sensitivity 93%, specificity 77%, PPV 7.1,
nd
NPV 99%; 2 trimester: prevalence 2.9%,
sensitivity 100%, specificity 85%, PPV 17%, NPV
100%.
1 study (n=1,000) showed more cesarean
deliveries in the screened group. A second study
(n=93) found the incidence of macrosomia ( ≥4.3
kg) was the same in screened and unscreened
groups (7% each group).
Based on the small number of studies and
sample sizes, the effect of screening women for
GDM on health outcomes is inconclusive.
Table 24. Summary of Evidence for all Key Questions (continued)
Key Question
Number and Quality
of Studies
Limitations/
Consistency
Applicability
Summary of Findings
•
Maternal outcomes:
KQ3: In the
absence of
treatment, how do
health outcomes
of mothers who
meet various
criteria for GDM
and their offspring
compare to those
who do not meet
the various
criteria?
38 prospective or
retrospective cohort
studies; 2 studies
were long-term
followup from RCTs;
however, only data
from the untreated
patients were
included.
Fair to good quality
Limitations: Strength of
evidence was low to
insufficient for all graded
outcomes due to risk of bias
(all observational studies),
inconsistency, and/or
imprecision. For many
comparisons, the numbers of
studies, participants, and/or
events was low; therefore,
findings of no statistically
significant differences
between groups do not imply
equivalence or rule out
potential differences.
Consistency: A wide variety
of diagnostic criteria and
thresholds were compared
across studies. There were
often few studies with similar
comparison groups.
Differences in defining and
assessing outcomes may
have contributed to
heterogeneity in results
across studies (e.g.,
biochemical vs. clinical
assessment of neonatal
hypoglycemia).
•
All studies or groups
included for analysis
involved women who had
not received treatment for
GDM. These women may
differ from the general
population in other ways
that are related to the
reasons that they did not
seek or receive early
prenatal care (e.g.,
socioeconomic status).
•
•
115
A methodologically strong study showed a
continuous positive relationship between
increasing glucose levels and the incidence of
primary cesarean section. This study also found
significantly fewer cases of preeclampsia and
cesarean section for women with no GDM vs.
IADPSG.
For preeclampsia, significant differences were
found for CC vs. patients with no GDM (3
studies), with fewer cases among the patients
with no GDM, and for CC vs. false-positive
groups (2 studies), with fewer cases among the
false positives. The strength of evidence was low.
No differences were found for NDDG false
positive (2 studies), NDDG 1 abnormal OGTT vs.
no GDM (1 study), or IGT WHO vs. no GDM (3
studies); the strength of evidence was
insufficient.
For maternal weight gain, significant differences
were found for 3 of 12 comparisons: IADPSG IGT
vs. no GDM (favored IGT), IADPSG IFG vs. no
GDM (favored IFG), IADPSG IGT-2 vs. no GDM
(favored IGT-2). All comparisons were based on
single studies (strength of evidence insufficient).
Fetal/neonatal/child outcomes:
2 methodologically strong studies showed a
continuous positive relationship between
increasing glucose levels and the incidence of
macrosomia. 1 of these studies also showed
significantly fewer cases of shoulder dystocia
and/or birth injury, clinical neonatal
hypoglycemia, and hyperbilirubinemia for women
with no GDM vs. IADPSG.
Table 24. Summary of Evidence for all Key Questions (continued)
Key Question
Number and Quality
of Studies
Limitations/
Consistency
Applicability
KQ3: In the
absence of
treatment, how do
health outcomes
of mothers who
meet various
criteria for GDM
and their offspring
compare to those
who do not meet
the various
criteria?
•
•
(continued)
116
Summary of Findings
For macrosomia >4,000 g, 6 of 11 comparisons
showed a significant difference: patient groups
with no GDM had fewer cases compared with CC
GDM (10 studies), CC 1 abnormal OGTT (7
studies), NDDG GDM (unrecognized) (1 study),
NDDG false positives (4 studies), and WHO IGT
(1 study). Fewer cases were found for women
with false-positive results compared with CC
GDM (5 studies). Data for macrosomia >4,500 g
were available for 4 comparisons and showed
significant differences in 2 cases: patient groups
with no GDM had fewer cases compared with CC
GDM (3 studies) and unrecognized NDDG GDM
(1 study). The strength of evidence for
macrosomia was low to insufficient.
For shoulder dystocia, significant differences
were found for 7 of 17 comparisons; all
comparisons but 1 were based on single studies
(insufficient strength of evidence). Patient groups
with no GDM showed lower incidence of shoulder
dystocia when compared with CC GDM (5
studies, low strength of evidence), NDDG GDM
(unrecognized), NDDG false positive, WHO IGT,
IADPSG IFG, and IADPSG IGT IFG. The other
significant difference showed lower incidence
among the false-positive group compared with
CC 1 abnormal OGTT.
Table 24. Summary of Evidence for all Key Questions (continued)
Key Question
Number and Quality
of Studies
Limitations/
Consistency
Applicability
KQ3: In the
absence of
treatment, how do
health outcomes
of mothers who
meet various
criteria for GDM
and their offspring
compare to those
who do not meet
the various
criteria?
(continued)
KQ4: Does
treatment modify
the health
outcomes of
mothers who meet
various criteria for
GDM and
offspring?
5 RCTs and 6
retrospective cohort
studies.
Poor to good quality
Limitations: For some
outcomes, particularly the
long-term outcomes, the
strength of evidence was
insufficient or low. Moreover,
for some outcomes events
were rare and the studies
may not have had the power
to detect clinically important
differences between groups;
therefore, findings of no
significant difference should
not be interpreted as
equivalence between groups.
For the most part, study
populations included
women whose glucose
intolerance was less
marked, as those whose
glucose intolerance was
more pronounced would
not be entered into a trial
in which they may be
assigned to a group
receiving no treatment.
The majority of studies
were conducted in North
America or Australia, with
2 from Italy. Most of the
North American studies
were inclusive of mixed
racial populations and
are likely applicable to
the general U.S.
population. Even though
the Australian RCT
population had more
white women with a lower
117
•
Summary of Findings
For fetal birth trauma/injury, single studies
compared CC GDM and WHO IGT with no GDM
and showed no differences. Two studies
showed fewer cases for no GDM compared with
NDDG GDM. Strength of evidence was
insufficient for all comparisons.
•
No differences were found for neonatal
hypoglycemia for any comparison, including CC
GDM vs. no GDM (3 studies), CC GDM vs. 1
abnormal OGTT (1 study), CC 1 abnormal
OGTT vs. no GDM (4 studies), NDDG GDM vs.
no GDM (1 study), NDDG false positive vs. no
GDM (1 study), and WHO IGT vs. no GDM (3
studies). Strength of evidence was insufficient
for all comparisons.
Maternal outcomes:
•
•
Moderate evidence from 3 RCTs showed a
significant difference for preeclampsia, with
fewer cases in the treated group.
There was inconsistency across studies in terms
of maternal weight gain (4 RCTs and 2 cohort
studies); the strength of evidence was
insufficient due to inconsistency and imprecision
in effect estimates.
Offspring outcomes:
•
•
There was insufficient evidence to make a
conclusion for birth injury. There was
inconsistency across studies with the 2 RCTs
showing no difference and the 1 cohort study
showing a difference in favor of the treated
group. The low number of events and
participants across all studies resulted in
imprecise estimates.
Moderate evidence showed significantly lower
incidence of shoulder dystocia in the treated
groups, and this finding was consistent for the 3
RCTs and 4 cohort studies.
Table 24. Summary of Evidence for all Key Questions (continued)
Key Questions
Number and Quality
of Studies
KQ4: Does
treatment modify
the health
outcomes of
mothers who meet
various criteria for
GDM and
offspring?
(continued)
KQ5: What are the
harms of treating
GDM and do they
vary by diagnostic
approach?
4 RCTs and 1
retrospective cohort
study.
Fair to good quality
Limitations/
Consistency
Consistency: Some
inconsistency occurred at 2
levels. First, there were
inconsistencies for some
outcomes between RCTs
and observational studies
which may be attributable to
confounding and methods of
selecting study groups
(e.g.,historical control
groups). Second, in some
instances there were
inconsistencies across
studies within designs that
were often attributable to the
manner in which outcomes
were defined or assessed
(e.g., clinical vs. biochemical
assessment of neonatal
hypoglycemia).
Limitations: No study
evaluated costs and
resource allocation. Limited
evidence on harms. Limited
evidence for number of
prenatal visits and NICU
admissions. Findings of no
significant differences may
be attributable to low power
and should not be interpreted
as equivalence.
Consistency: Not applicable
(not enough studies
addressing the same
question to judge).
Applicability
BMI than the U.S. RCT;
this should not affect
applicability of most of
their findings for the U.S.
women because these
subject characteristics
would be factors
associated with lower risk
of poor outcomes.
Summary of Findings
•
•
•
•
•
As above for KQ4. In
addition, differences in
billing structures between
the United States and
Australia may have
accounted for the
discrepant findings with
respect to NICU
admissions between
these studies and as a
result limit the
applicability of this finding
in the United States.
118
•
•
There was low evidence of no difference
between groups for neonatal hypoglycemia
based on 4 RCTs and 2 cohort studies.
For outcomes related to birthweight (including
macrosomia >4,000 g, macrosomia >4,500 g,
actual birthweight, and large for gestational
age), differences were often observed favoring
the treated groups. Strength of evidence was
moderate for macrosomia >4,000 g.
1 RCT followed patients for 7 to 11 years and
found no differences for impaired glucose
tolerance or type 2 DM, although the strength of
evidence was considered insufficient.
No differences were observed in single studies
that assessed BMI >95 (7-11 year followup) and
BMI >85 percentile (5-7 year followup). Overall,
pooled results showed no difference in BMI, and
the strength of evidence was considered low
1 RCT assessed depression and anxiety at 6
weeks after study entry and 3 months
postpartum.
There was no significant difference between
groups in anxiety at either time point, although
there were significantly lower rates of
depression in the treatment group at 3 months
postpartum.
4 RCTs reported small for gestational age and
found no significant difference.
3 RCTs and 1 cohort study provided data on
admission to NICU and showed no significant
differences overall. One trial was an outlier
because it showed a significant difference
favoring the no treatment group. This difference
may be attributable to site-specific policies and
procedures.
Table 24. Summary of Evidence for all Key Questions (continued)
Key Questions
Number and Quality
of Studies
Limitations/
Consistency
Applicability
•
Summary of Findings
2 RCTs reported on the number of prenatal
visits and generally found more visits among the
treatment groups.
KQ5: What are the
harms of treating
•
2 RCTs reporting on induction of labor showed
GDM and do they
different results, with 1 showing a significant
vary by diagnostic
difference with more cases in the treatment
approach?
group and the other showing no difference.
•
Based on studies included in KQ4, no
(continued)
differences between groups were found for
cesarean section (5 RCTs, 6 cohorts) or
unplanned cesarean section (1 RCT, 1 cohort).
ADA = American Diabetes Association; ADIPS = Australasian Diabetes in Pregnancy Society; BMI = body mass index; CC = Carpenter-Coustan; DM = diabetes mellitus;
FPG = fasting plasma glucose; GDM = gestational diabetes mellitus; HbA1c = glycated hemoglobin; IADPSG = International Association of Diabetes in Pregnancy Study Groups;
IFG = impaired fasting glucose; IGT = impaired glucose tolerance; IGT-2 = double impaired glucose intolerance; JSOG = Japan Society of Obstetrics and Gynecology; KQ = Key
Question; NDDG = National Diabetes Data Group; NPV = negative predictive value; NICU = neonatal intensive care unit; OGCT = oral glucose challenge test; OGTT = oral
glucose tolerance test; PPV = positive predictive value; RCT = randomized controlled trial; wk(s) = week(s); WHO = World Health Organization
119
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Acronyms and Abbreviations
ACHOIS
ACOG
ADA
ADIPS
BMI
CC
CI
D
dL
DM
Dx
EASD
FPG
GCT/OGCT
GDM
g(s)
h(s)
HSROC
HAPO
HbA1c
IFG
IGT
IGT-2
IADPSG
IQR
IWC
JSOG
kg
LGA
L
m
MD
µmol
mg
mmol
mo(s)
NDDG
NICU
NOS
NR
N or n
Australian Carbohydrate Intolerance in Pregnant Women Study
American Congress of Obstetricians and Gynecologists
American Diabetes Association
Australasian Diabetes in Pregnancy Society
Body-mass index
Carpenter and Coustan
Confidence interval
Day(s)
Deciliter
Diabetes mellitus
Diagnosis/diagnostic
European Association for the Study of Diabetes
Fasting plasma glucose
Glucose tolerance test and oral glucose tolerance test are synonymous
Gestational diabetes mellitus
Gram(s)
Hour(s)
Hierarchical summary receiver operator characteristic
Hyperglycemia and Adverse Pregnancy Outcomes Study
Glycated Hemoglobin, Hemoglobin A1c
Impaired fasting glucose
Impaired glucose tolerance
Double impaired glucose tolerance
International Association of the Diabetes in Pregnancy Study Groups
Inter-quartile range
International Workshop Conference
Japan Society of Obstetrics and Gynecology
kilogram
Large for gestational age
Liter
Meter
Mean difference
Micromole
Milligrams
Millimole
Month(s)
National Diabetes Data Group
Neonatal Intensive Care Unit
Newcastle-Ottawa Quality Assessment Scale
Not reported
Number
130
NPV
OGCT
OGTT
PCS
PPV
QUADAS
RCS
RCT(s)
RDS
RR
Sn
Sp
SD
SGA
WHO
wk(s)
yr(s)
Negative predictive value
Oral glucose challenge text
Oral glucose tolerance test
Prospective cohort study
Positive predictive value
Quality assessment of diagnostic accuracy studies
Retrospective cohort study
Randomized controlled trial(s)
Respiratory distress syndrome
Risk ratio (or relative risk)
Sensitivity
Specificity
Standard deviation
Small for gestational age
World Health Organization
Week(s)
Year(s)
131
Appendix A. Literature Search Strings
Table A1.
Table A2.
Table A3.
Table A4.
Table A5.
Table A6.
Table A7.
Table A8.
Table A9.
Table A10.
Table A11.
Table A12.
Table A13.
Table A14.
MEDLINE
Embase
EBM Reviews
Global Health
PASCAL
Medline® In Process
CINAHL Plus with Full Text
Biosis Previews ®
Science Citation Index Expanded ®
Conference Proceedings Citation Index—Science
LILACs (Latin American and Caribbean Health Science Literature)
OCLC ProceedingsFirst and PapersFirst
PubMed
ClinicalTrials.gov and WHO
A-1
Table A1. Medline
Database: Medline via Ovid <1948 to September Week 4 2011>
Search Date: 9 October 2011
Results: 8,234
1.
Diabetes, Gestational/
2.
Fetal Macrosomia/
3.
Pregnancy Complications/
4.
GDM.tw.
5.
(gestation$ adj2 (diabet$ or DM or glucose intoleran$ or insulin resistan$)).mp.
6.
(pregnan$ adj3 (diabet$ or DM or glucose intoleran$ or insulin resistan$)).mp.
7.
(maternal adj2 (diabet$ or DM or glyc?emia or hyperglyc?emia)).tw.
8.
(hyperglyc?emia adj2 pregnan$).tw.
9.
macrosomia.tw.
10.
or/1-9
11.
mass screening/
12.
prenatal diagnosis/
13.
screen$.tw.
14.
((prenatal or early) adj2 diagnosis).tw.
15.
Glucose Tolerance Test/
16.
Glucose Intolerance/
17.
Blood Glucose/
18.
Risk Factors/
19.
(glucose adj (tolerance or intolerance or challenge)).tw.
20.
OGTT.tw.
21.
GCT.tw.
22.
(fasting adj2 glucose).tw.
23.
or/11-22
24.
"Sensitivity and Specificity"/
25.
"Predictive Value of Tests"/
26.
ROC Curve/
27.
specific$.tw.
28.
sensitiv$.tw.
29.
predictive value.tw.
30.
accurac$.tw.
31.
diagnostic errors/
32.
diagnostic error?.tw.
33.
false negative reactions/
34.
false positive reactions/
35.
(false adj (negative or positive)).tw.
36.
"reproducibility of results"/
37.
reference values/
38.
reference standards/
39.
or/24-38
40.
and/10,23,39
41.
intervention?.mp.
42.
(treating or treatment? or therapy or therapies).mp.
43.
manage$.mp.
44.
monitor$.mp.
45.
exp sulfonylurea compounds/
46.
Gliclazide/
47.
Glyburide/
48.
Tolbutamide/
49.
sulfonylurea?.tw.
50.
gliclazid$.tw.
51.
glimepirid$.tw.
52.
glipizid$.tw.
53.
glyburid$.tw.
54.
tolbutamid$.tw.
55.
(antidiabet$ or anti-diabet$).tw.
56.
insulin?.mp.
57.
glibenclamid$.mp.
58.
acarbos$.mp.
A-2
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
76.
77.
78.
79.
80.
81.
82.
83.
84.
85.
86.
87.
88.
89.
90.
91.
92.
93.
94.
95.
96.
97.
98.
99.
100.
101.
102.
103.
104.
105.
106.
107.
108.
109.
110.
111.
112.
113.
114.
115.
116.
117.
118.
119.
120.
exp Diet Therapy/
(diet adj2 (therap$ or restrict$ or advice)).tw.
medical nutrition$ therapy.tw.
MNT.tw.
exp Life Style/
(lifestyle$ or life-style$).mp.
Blood Glucose Self-Monitoring/
(blood glucose adj (self monitor$ or self-monitor$)).tw.
((self monitor$ or self-monitor$) adj blood glucose).tw.
SMBG.tw.
Counseling/
counsel$.tw.
Labor, Induced/
(induc$ adj2 labo?r).tw.
exp Cesarean Section/
c?esarean.tw.
exp Pregnancy Outcome/
pregnanc$ outcome?.tw.
or/41-76
and/10,77
or/40,78
clinical trial.pt.
randomized controlled trial.pt.
randomi?ed.ti,ab.
placebo.ti,ab.
dt.fs.
randomly.ti,ab.
trial.ti,ab.
groups.ti,ab.
or/80-87
animals/
humans/
89 not (89 and 90)
88 not 91
cohort studies/
follow-up studies/
longitudinal studies/
prospective studies/
retrospective studies/
((cohort? or follow-up or followup or longitud$ or prospectiv$ or retrospectiv$) adj (study or studies or trial?)).tw.
or/93-98
99 not 91
exp Guideline/
Health Planning Guidelines/
(clinical adj2 guideline?).tw.
CPG?.tw.
((practice or consensus or position) adj2 (guideline? or recommendation? or statement?)).tw.
standard?.tw.
protocol?.tw.
or/101-107
meta analysis.mp,pt.
review.pt.
search:.tw.
or/109-111 [Reviews balanced - HIRU]
and/79,92 [Clinical trials & RCTs]
and/79,100 [Observational studies]
and/79,108 [Guidelines]
and/79,112 [SRs MAs]
or/113-116
limit 117 to (english language and yr="2000 -Current")
limit 117 to (english language and yr="2000 -2005")
limit 117 to (english language and yr="2006 -Current")
A-3
121.
122.
123.
124.
125.
126.
127.
128.
129.
130.
131.
132.
133.
134.
135.
136.
137.
138.
remove duplicates from 119
remove duplicates from 120
or/121-122
113 or 114 or 115
113 or 114 or 115
limit 125 to (english language and yr="2000 -Current")
limit 125 to (english language and yr="2000 -2005")
remove duplicates from 127
limit 125 to (english language and yr="2006 -Current")
remove duplicates from 129
128 or 130
113 or 114
limit 132 to (english language and yr="2000 -Current")
limit 132 to (english language and yr="2000 -2005")
remove duplicates from 134
limit 132 to (english language and yr="2006 -Current")
remove duplicates from 136
135 or 137
Table A2. Embase
Database: Embase via Ovid <1996 to 2011 Week 40>
Search Date: 10 October 2011
Results: 5,188
1.
pregnancy diabetes mellitus/
2.
maternal diabetes mellitus/
3.
pregnancy complication/
4.
macrosomia/
5.
GDM.tw.
6.
(gestation$ adj2 (diabet$ or DM or glucose intoleran$ or insulin resistan$)).mp.
7.
(pregnan$ adj3 (diabet$ or DM or glucose intoleran$ or insulin resistan$)).mp.
8.
(maternal adj2 (diabet$ or DM or glyc?emia or hyperglyc?emia)).mp.
9.
(hyperglyc?emia adj2 pregnan$).tw.
10.
macrosomia.tw.
11.
or/1-10
12.
prenatal screening/
13.
early diagnosis/
14.
screen$.tw.
15.
((prenatal or early) adj2 diagnosis).tw.
16.
exp glucose tolerance test/
17.
glucose intolerance/
18.
glucose blood level/
19.
risk factor/
20.
(glucose adj (tolerance or intolerance or challenge)).tw.
21.
OGTT.tw.
22.
GCT.tw.
23.
(fasting adj2 glucose).tw.
24.
or/12-23
25.
"sensitivity and specificity"/
26.
predictive value/
27.
receiver operating characteristic/
28.
specific$.tw.
29.
sensitiv$.tw.
30.
predictive value.tw.
31.
accurac$.tw.
32.
diagnostic error/
33.
diagnostic accuracy/
34.
diagnostic error?.tw.
35.
false negative result/
36.
false positive result/
37.
(false adj (negative or positive)).tw.
38.
reproducibility/
A-4
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
76.
77.
78.
79.
80.
81.
82.
83.
84.
85.
86.
87.
88.
89.
90.
91.
92.
93.
94.
95.
96.
97.
98.
99.
100.
reference value/
standard/
or/25-40
and/11,24,41
intervention?.mp.
(treating or treatment? or therapy or therapies).mp.
manage$.mp.
monitor$.mp.
sulfonylurea derivative/
gliclazide/
glibenclamide/
glimepiride/
glipizide/
tolbutamide/
sulfonylurea?.tw.
gliclazid$.tw.
glimepirid$.tw.
glipizid$.tw.
glyburid$.tw.
tolbutamid$.tw.
(antidiabet$ or anti-diabet$).tw.
insulin?.mp.
glibenclamid$.mp.
acarbos$.mp.
exp diet therapy/
(diet adj2 (therap$ or restrict$ or advice)).tw.
medical nutrition$ therapy.tw.
MNT.tw.
exp lifestyle/
(lifestyle$ or life-style$).mp.
blood glucose monitoring/
(blood glucose adj (self monitor$ or self-monitor$)).tw.
((self monitior$ or self-monitor$) adj blood glucose).tw.
SMBG.tw.
counseling/
nutritional counseling/
counsel$.tw.
labor induction/
(induc$ adj2 labo?r).tw.
cesarean section/
c?esarean.tw.
pregnancy outcome/
pregnanc$ outcome?.tw.
or/43-81
and/11,82
or/42,83
clinical trial/
randomized controlled trial/
randomization/
single blind procedure/
double blind procedure/
crossover procedure/
placebo/
randomi?ed controlled trial?.tw.
RCT.tw.
random allocation.tw.
randomly allocated.tw.
allocated randomly.tw.
(allocated adj2 random).tw.
single blind$.tw.
double blind$.tw.
((treble or triple) adj blind$).tw.
A-5
101.
placebo$.tw.
102.
prospective study/
103.
or/85-102
104.
case study/
105.
case report.tw.
106.
abstract report/ or letter/
107.
or/104-106
108.
103 not 107 [SIGN Embase RCT filter]
109.
animal/
110.
human/
111.
109 not (109 and 110)
112.
108 not 111
113.
cohort analysis/
114.
follow up/
115.
longitudinal study/
116.
prospective study/
117.
retrospective study/
118.
((cohort? or follow-up or followup or longitud$ or prospectiv$ or retrospectiv$) adj (study or studies or trial?)).tw.
119.
or/113-118
120.
119 not 111
121.
exp practice guideline/
122.
(clinical adj2 guideline?).tw.
123.
CPG?.tw.
124.
((practice or consensus or position) adj2 (guideline? or recommendation? or statement?)).tw.
125.
standard?.tw.
126.
protocol?.tw.
127.
or/121-126 [Guidelines]
128.
and/84,112 [RCTs]
129.
and/84,120 [Observational studies]
130.
and/84,127 [Guidelines]
131.
or/128-130
132.
limit 131 to (english language and yr="2000 -2005")
133.
remove duplicates from 132
134.
limit 131 to (english language and yr="2006 -Current")
135.
remove duplicates from 134
133 or 135
Table A3. EMB Reviews
Databases:
Cochrane Central Register of Controlled Trials (CCTR) via Ovid <3rd Quarter 2011>
Cochrane Database of Systematic Reviews (CDSR) via Ovid <2005 to September 2011>
Database of Abstracts of Reviews of Effects (DARE) via Ovid <3rd Quarter 2011>
Search Date: 9 October 2011
Results: CCTR: 23; CDSR: 79; DARE: 23
1.
GDM.tw.
2.
(gestation$ adj2 (diabet$ or DM or glucose intoleran$ or insulin resistan$)).mp.
3.
(pregnan$ adj3 (diabet$ or DM or glucose intoleran$ or insulin resistan$)).mp.
4.
(maternal adj2 (diabet$ or DM or glyc?emia or hyperglyc?emia)).tw.
5.
(hyperglyc?emia adj2 pregnan$).tw.
6.
macrosomia.tw.
7.
or/1-6
8.
screen$.tw.
9.
((prenatal or early) adj2 diagnosis).tw.
10.
blood glucose.tw.
11.
risk factor?.tw.
12.
(glucose adj (tolerance or intolerance or challenge)).tw.
13.
OGTT.tw.
14.
GCT.tw.
15.
(fasting adj2 glucose).tw.
16.
or/8-15
17.
specific$.tw.
A-6
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
76.
77.
78.
79.
sensitiv$.tw.
predictive value.tw.
(ROC or "receiver operating characteristic?").tw.
accurac$.tw.
diagnostic error?.tw.
(false adj (negative or positive)).tw.
"reproducibility of results".tw.
(reference adj2 (standard? or value?)).tw.
or/17-25
and/7,16,26
intervention?.mp.
(treating or treatment? or therapy or therapies).mp.
manage$.mp.
monitor$.mp.
sulfonylurea?.tw.
gliclazid$.tw.
glimepirid$.tw.
glipizid$.tw.
glyburid$.tw.
tolbutamid$.tw.
(antidiabet$ or anti-diabet$).tw.
insulin?.mp.
glibenclamid$.mp.
acarbos$.mp.
(diet adj2 (therap$ or restrict$ or advice)).tw.
medical nutrition$ therapy.tw.
MNT.tw.
(lifestyle$ or life-style$).mp.
(blood glucose adj (self monitor$ or self-monitor$)).tw.
((self monitior$ or self-monitor$) adj blood glucose).tw.
SMBG.tw.
counsel$.tw.
(induc$ adj2 labo?r).tw.
c?esarean.tw.
pregnanc$ outcome?.tw.
or/28-52
and/7,53
or/27,54
clinical trial.pt.
randomized controlled trial.pt.
randomi?ed.ti,ab.
placebo.ti,ab.
dt.fs.
randomly.ti,ab.
trial.ti,ab.
groups.ti,ab.
or/56-63
(animal? not (animal? and human?)).mp.
64 not 65
((cohort? or follow-up or followup or longitud$ or prospectiv$ or retrospectiv$) adj (study or studies or trial?)).tw.
67 not 66
(clinical adj2 guideline?).tw.
CPG?.tw.
((practice or consensus or position) adj2 (guideline? or recommendation? or statement?)).tw.
standard?.tw.
protocol?.tw.
or/69-73
and/55,66 [Clinical trials & RCTs]
and/55,68 [Observational studies]
and/55,74 [Guidelines]
or/75-77
limit 78 to (english language and yr="2000-Current")
A-7
80.
remove duplicates from 79
Table A4. Global Health
Database: Global Health via Ovid <1973 to September 2011>
Search Date: 9 October 2011
Results: 361
1.
GDM.tw.
2.
(gestation$ adj2 (diabet$ or DM or glucose intoleran$ or insulin resistan$)).mp.
3.
(pregnan$ adj3 (diabet$ or DM or glucose intoleran$ or insulin resistan$)).mp.
4.
(maternal adj2 (diabet$ or DM or glyc?emia or hyperglyc?emia)).tw.
5.
(hyperglyc?emia adj2 pregnan$).tw.
6.
macrosomia.tw.
7.
or/1-6
8.
screen$.tw.
9.
((prenatal or early) adj2 diagnosis).tw.
10.
blood glucose.tw.
11.
risk factor?.tw.
12.
(glucose adj (tolerance or intolerance or challenge)).tw.
13.
OGTT.tw.
14.
GCT.tw.
15.
(fasting adj2 glucose).tw.
16.
or/8-15
17.
specific$.tw.
18.
sensitiv$.tw.
19.
predictive value.tw.
20.
(ROC or "receiver operating characteristic?").tw.
21.
accurac$.tw.
22.
diagnostic error?.tw.
23.
(false adj (negative or positive)).tw.
24.
"reproducibility of results".tw.
25.
(reference adj2 (standard? or value?)).tw.
26.
or/17-25
27.
and/7,16,26
28.
intervention?.mp.
29.
(treating or treatment? or therapy or therapies).mp.
30.
manage$.mp.
31.
monitor$.mp.
32.
sulfonylurea?.tw.
33.
gliclazid$.tw.
34.
glimepirid$.tw.
35.
glipizid$.tw.
36.
glyburid$.tw.
37.
tolbutamid$.tw.
38.
(antidiabet$ or anti-diabet$).tw.
39.
insulin?.mp.
40.
glibenclamid$.mp.
41.
acarbos$.mp.
42.
(diet adj2 (therap$ or restrict$ or advice)).tw.
43.
medical nutrition$ therapy.tw.
44.
MNT.tw.
45.
(lifestyle$ or life-style$).mp.
46.
(blood glucose adj (self monitor$ or self-monitor$)).tw.
47.
((self monitior$ or self-monitor$) adj blood glucose).tw.
48.
SMBG.tw.
49.
counsel$.tw.
50.
(induc$ adj2 labo?r).tw.
51.
c?esarean.tw.
52.
pregnanc$ outcome?.tw.
53.
or/28-52
54.
and/7,53
55.
or/27,54
A-8
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
76.
77.
78.
79.
80.
clinical trial.pt.
randomized controlled trial.pt.
randomi?ed.ti,ab.
placebo.ti,ab.
dt.fs.
randomly.ti,ab.
trial.ti,ab.
groups.ti,ab.
or/56-63
(animal? not (animal? and human?)).mp.
64 not 65
((cohort? or follow-up or followup or longitud$ or prospectiv$ or retrospectiv$) adj (study or studies or trial?)).tw.
67 not 66
(clinical adj2 guideline?).tw.
CPG?.tw.
((practice or consensus or position) adj2 (guideline? or recommendation? or statement?)).tw.
standard?.tw.
protocol?.tw.
or/69-73
and/55,66 [Clinical trials & RCTs]
and/55,68 [Observational studies]
and/55,74 [Guidelines]
or/75-77
limit 78 to (english language and yr="2000-Current")
remove duplicates from 79
Table A5. PASCAL
Database: PASCAL via Ovid <1984 to 2011 Week 39>
Search Date: 9 October 2011
Results: 498
1.
GDM.tw.
2.
(gestation$ adj2 (diabet$ or DM or glucose intoleran$ or insulin resistan$)).mp.
3.
(pregnan$ adj3 (diabet$ or DM or glucose intoleran$ or insulin resistan$)).mp.
4.
(maternal adj2 (diabet$ or DM or glyc?emia or hyperglyc?emia)).tw.
5.
(hyperglyc?emia adj2 pregnan$).tw.
6.
macrosomia.tw.
7.
or/1-6
8.
screen$.tw.
9.
((prenatal or early) adj2 diagnosis).tw.
10.
blood glucose.tw.
11.
risk factor?.tw.
12.
(glucose adj (tolerance or intolerance or challenge)).tw.
13.
OGTT.tw.
14.
GCT.tw.
15.
(fasting adj2 glucose).tw.
16.
or/8-15
17.
specific$.tw.
18.
sensitiv$.tw.
19.
predictive value.tw.
20.
(ROC or "receiver operating characteristic?").tw.
21.
accurac$.tw.
22.
diagnostic error?.tw.
23.
(false adj (negative or positive)).tw.
24.
"reproducibility of results".tw.
25.
(reference adj2 (standard? or value?)).tw.
26.
or/17-25
27.
and/7,16,26
28.
intervention?.mp.
29.
(treating or treatment? or therapy or therapies).mp.
30.
manage$.mp.
31.
monitor$.mp.
A-9
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
76.
77.
78.
79.
80.
sulfonylurea?.tw.
gliclazid$.tw.
glimepirid$.tw.
glipizid$.tw.
glyburid$.tw.
tolbutamid$.tw.
(antidiabet$ or anti-diabet$).tw.
insulin?.mp.
glibenclamid$.mp.
acarbos$.mp.
(diet adj2 (therap$ or restrict$ or advice)).tw.
medical nutrition$ therapy.tw.
MNT.tw.
(lifestyle$ or life-style$).mp.
(blood glucose adj (self monitor$ or self-monitor$)).tw.
((self monitior$ or self-monitor$) adj blood glucose).tw.
SMBG.tw.
counsel$.tw.
(induc$ adj2 labo?r).tw.
c?esarean.tw.
pregnanc$ outcome?.tw.
or/28-52
and/7,53
or/27,54
clinical trial.pt.
randomized controlled trial.pt.
randomi?ed.ti,ab.
placebo.ti,ab.
dt.fs.
randomly.ti,ab.
trial.ti,ab.
groups.ti,ab.
or/56-63
(animal? not (animal? and human?)).mp.
64 not 65
((cohort? or follow-up or followup or longitud$ or prospectiv$ or retrospectiv$) adj (study or studies or trial?)).tw.
67 not 66
(clinical adj2 guideline?).tw.
CPG?.tw.
((practice or consensus or position) adj2 (guideline? or recommendation? or statement?)).tw.
standard?.tw.
protocol?.tw.
or/69-73
and/55,66 [Clinical trials & RCTs]
and/55,68 [Observational studies]
and/55,74 [Guidelines]
or/75-77
limit 78 to (english language and yr="2000-Current")
remove duplicates from 79
Table A6. Medline In-Process & Other Non-Indexed Citations
Database: Medline In-Process & Other Non-Indexed Citations <October 7, 2011>
Search Date: 7 October 2011
Results: 98
1.
GDM.tw.
2.
(gestation$ adj2 (diabet$ or DM or glucose intoleran$ or insulin resistan$)).mp.
3.
(pregnan$ adj3 (diabet$ or DM or glucose intoleran$ or insulin resistan$)).mp.
4.
(maternal adj2 (diabet$ or DM or glyc?emia or hyperglyc?emia)).tw.
5.
(hyperglyc?emia adj2 pregnan$).tw.
6.
macrosomia.tw.
7.
or/1-6
8.
screen$.tw.
A-10
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
((prenatal or early) adj2 diagnosis).tw.
blood glucose.tw.
risk factor?.tw.
(glucose adj (tolerance or intolerance or challenge)).tw.
OGTT.tw.
GCT.tw.
(fasting adj2 glucose).tw.
or/8-15
specific$.tw.
sensitiv$.tw.
predictive value.tw.
(ROC or "receiver operating characteristic?").tw.
accurac$.tw.
diagnostic error?.tw.
(false adj (negative or positive)).tw.
"reproducibility of results".tw.
(reference adj2 (standard? or value?)).tw.
or/17-25
and/7,16,26
intervention?.mp.
(treating or treatment? or therapy or therapies).mp.
manage$.mp.
monitor$.mp.
sulfonylurea?.tw.
gliclazid$.tw.
glimepirid$.tw.
glipizid$.tw.
glyburid$.tw.
tolbutamid$.tw.
(antidiabet$ or anti-diabet$).tw.
insulin?.mp.
glibenclamid$.mp.
acarbos$.mp.
(diet adj2 (therap$ or restrict$ or advice)).tw.
medical nutrition$ therapy.tw.
MNT.tw.
(lifestyle$ or life-style$).mp.
(blood glucose adj (self monitor$ or self-monitor$)).tw.
((self monitior$ or self-monitor$) adj blood glucose).tw.
SMBG.tw.
counsel$.tw.
(induc$ adj2 labo?r).tw.
c?esarean.tw.
pregnanc$ outcome?.tw.
or/28-52
and/7,53
or/27,54
clinical trial.pt.
randomized controlled trial.pt.
randomi?ed.ti,ab.
placebo.ti,ab.
dt.fs.
randomly.ti,ab.
trial.ti,ab.
groups.ti,ab.
or/56-63
(animal? not (animal? and human?)).mp.
64 not 65
((cohort? or follow-up or followup or longitud$ or prospectiv$ or retrospectiv$) adj (study or studies or trial?)).tw.
67 not 66
(clinical adj2 guideline?).tw.
CPG?.tw.
A-11
71.
72.
73.
74.
75.
76.
77.
78.
79.
80.
((practice or consensus or position) adj2 (guideline? or recommendation? or statement?)).tw.
standard?.tw.
protocol?.tw.
or/69-73
and/55,66 [Clinical trials & RCTs]
and/55,68 [Observational studies]
and/55,74 [Guidelines]
or/75-77
limit 78 to (english language and yr="2000-Current")
remove duplicates from 79
A7. CINAHL Plus with Full Text
Database: CINAHL Plus with Full Text via EBSCO <1937–current>
Search Date: 10 October 2011
Results: 275
S39= S35 or S37 or S38
S38= S25 and S33 Limiters - English Language; Published Date from: 20000101-20121231; Exclude MEDLINE records
S37= S25 and S32 Limiters - English Language; Published Date from: 20000101-20121231; Exclude MEDLINE records
S36= S25 and S32
S35= S25 and S31 Limiters - English Language; Published Date from: 20000101-20121231; Exclude MEDLINE records
S34= S25 and S31
S33=( CPG? or "best practice?" or "professional standard?" or "standard of care" ) OR ( practice W2 guideline* or practice W2
recommendation* or practice W2 statement or position W2 guideline* or position W2 recommendation* or position W2
statement or consensus W2 guideline* or consensus W2 recommendation* or consensus W2 statement )
S32=( (MH "Prospective Studies+") OR (MH "Retrospective Design") ) OR TI ( cohort* or follow-up or followup or longitud*
or prospectiv* or retrospective* ) OR AB ( cohort* or follow-up or followup or longitud* or prospectiv* or retrospective* )
S31= S26 or S27 or S28 or S29 or S30
S30=(MH "Placebos") OR TX placebo* OR (MH "Quantitative Studies")
S29= TX randomi* control* trial* OR (MH "Random Assignment") OR TX random* allocat* OR TX allocat* random*
S28= TX clinic* n1 trial* OR ( TX ( (singl* n1 blind*) or (singl* n1 mask*) ) or TX ( (doubl* n1 blind*) or (doubl* n1 mask*) )
or TX ( (tripl* n1 blind*) or (tripl* n1 mask*) ) or TX ( (trebl* n1 blind*) or (trebl* n1 mask*) ) )
S27= PT Clinical trial
S26=(MH "Clinical Trials+")
S25= S14 or S24
S24= S5 and S23
S23= S15 or S16 or S17 or S18 or S19 or S20 or S21 or S22
S22=( (MH "Labor, Induced") OR (MH "Cesarean Section+") OR (MH "Pregnancy Outcomes") ) OR ( induc* n2 labo#r or
cesarean or caesarean or pregnan* n1 outcome* )
S21=( (MH "Counseling") OR (MH "Nutritional Counseling") ) OR counsel*
S20=(MH "Blood Glucose Self-Monitoring") OR ( "blood glucose" w1 "self monitor*" or "blood glucose" w1 "self-monitor*" )
OR SMBG
S19=(MH "Life Style Changes") OR ( lifestyle* or life-style* )
S18=(MH "Diet Therapy") OR ( diet w2 therap* or diet w2 restrict* or diet w2 advice ) OR ( "medical nutrition therapy" or MNT
)
S17=( sulfonyurea? or gliclazid* or glimepirid* or glipizid* or glyburid* or tolbutamid* ) OR ( antidiabet* or anti-diabet* ) OR (
insulin* or glibenclamid* or acarbos* )
S16=(MH "Sulfonylurea Compounds+")
S15= intervention* or treating or treatment* or therapy or therapies or manage* or monitor*
S14= S5 and S10 and S13
S13= S11 or S12
S12=( specific* or sensitiv* or predictive w1 value* or accurac* or diagnostic w1 error* ) OR ( false w1 negative or false w1
positive )
S11=(MH "Diagnostic Errors") OR (MH "Reproducibility of Results") OR (MH "False Negative Results") OR (MH "False
Positive Results") OR (MH "Predictive Value of Tests") OR (MH "Sensitivity and Specificity") OR (MH "ROC Curve") OR
(MH "Reference Values")
S10= S6 or S7 or S8 or S9
S9=( glucose n1 tolerance or glucose n1 intolerance or glucose n1 challenge ) OR ( OGTT or GCT ) OR fasting w2 glucose
S8=(MH "Glucose Tolerance Test") OR (MH "Blood Glucose Monitoring") OR (MH "Glucose Intolerance") OR (MH "Blood
Glucose") OR (MH "Risk Assessment")
S7= screen* OR ( prenatal n2 diagnosis or early n2 diagnosis )
S6=(MH "Neonatal Assessment") OR (MH "Health Screening+") OR (MH "Prenatal Diagnosis+")
A-12
S5= S1 or S2 or S3 or S4
S4= hyperglyc#emia n2 pregnan* OR macrosomia
S3=( gestation* n2 diabet* or gestation* n2 DM or gestation* n2 glucose intoleran* or gestation* n2 insulin resistan* ) OR (
pregnan* n2 diabet* or pregnan* n2 DM or pregnan* n2 glucose intoleran* or pregnan* n2 insulin resistan* ) OR ( maternal n2
diabet* or maternal n2 DM or maternal n2 glucose intoleran* or maternal n2 insulin resistan* )
S2=( (MM "Diabetes Mellitus, Gestational") OR (MH "Pregnancy Complications") OR (MH "Fetal Macrosomia") ) OR GDM
S1=(MM "Diabetes Mellitus, Gestational") OR (MH "Pregnancy Complications") OR (MH "Fetal Macrosomia")
Table A8. BIOSIS Preview®
Database: Biosis Previews ® via Web of KnowledgeSM <1926–present>
Search Date: 9 October 2011
Results: 34
# 17
(#16 OR #15 OR #14) AND Language=(English)
# 16
(#9) AND Language=(English) AND Document Types=(Meeting OR Meeting Paper) AND Literature Type=(Meeting
Abstract OR Meeting Address OR Meeting Paper OR Meeting Poster OR Meeting Report OR Meeting Slide OR Meeting
Summary)
# 15
(#13 AND #9) AND Language=(English
# 14
(#12 AND #9) AND Language=(English
# 13
(TS=( CPG* OR "best practice*" OR "professional standard*" OR "standard of care" OR (practice NEAR/2
guideline*) OR (practice NEAR/2 recommendation*) OR (practice NEAR/2 statement) OR (position NEAR/2 guideline*) OR
(position NEAR/2 recommendation*) OR (position NEAR/2 statement) OR (consensus NEAR/2 guideline*) OR (consensus
NEAR/2 recommendation*) OR (consensus NEAR/2 statement))) AND Language=(English)
# 12
(#10 NOT #11) AND Language=(English)
# 11
(TS=(animal* OR rat OR rats OR mouse OR mice OR rodent* OR rabbit OR rabbits OR horse OR horses OR equine
OR veterinar* OR bovine OR cow OR cows OR pig OR pigs OR porcine)) AND Language=(English)
# 10
((TS=(randomized controlled trial* OR controlled clinical trial* OR research design OR placebo* OR random*) OR
TS=(cohort* OR longitude* OR prospectiv* OR retrospectiv* OR long term OR long-term OR longterm OR followup OR
"follow up" OR follow-up) AND TS=(study OR studies OR trial))) AND Language=(English)
#9
(#8 OR #4) AND Language=(English)
#8
(#7 AND #1) AND Language=(English)
#7
(#6 OR #5) AND Language=(English)
#6
TS= ((diet NEAR/2 therap*) OR (diet NEAR/2 restrict*) OR (diet NEAR/2 advice) OR "medical nutrition* therapy"
OR MNT OR lifestyle* OR life-style* OR ("blood glucose" NEAR self-monitor*) OR ("blood glucose" NEAR "self monitor*")
OR SMBG OR counsel* OR (induc* NEAR labour) OR (induc* NEAR labor) OR cesarean OR caesarean OR (pregnan* NEAR
outcome*))) AND Language=(English)
#5
TS= (intervention* OR treat* OR therap* OR sulfonylurea* OR antidiabet* OR anti-diabet* OR gliclazid* OR
glimepirid* OR glipizid* OR glyburid* OR tolbutamid* OR antidiabet* OR anti-diabet* OR insulin* OR glibenclamid* OR
acarbos*)) AND Language=(English)
#4
#3 AND #2 AND #1
#3
TS=("sensitivity and specificity" OR sensitiv* OR specific* OR "predictive value" OR (diagnos* NEAR error*) OR
"false negative" OR "false positive" OR accurac*)) AND Language=(English)
#2
TS=( "prenatal screen*" OR (glucose NEAR/3 tolerance) OR (glucose NEAR/3 intoleran*) OR (glucose NEAR/3
challenge*) OR OGTT OR GCT OR "fasting glucose" OR "risk factor* ")) AND Language=(English)
#1
TS= ((gestation* NEAR/2 diabet*) OR (gestation* NEAR/2 "glucose intoleran*") OR (gestation* NEAR/2 "insulin
resist*") OR (pregnan* NEAR/2 diabet*) OR (pregnan* NEAR/2 "glucose intoleran*") OR (pregnan* NEAR/2 "insulin resist*")
OR (maternal NEAR/2 diabet*) OR (maternal NEAR/2 "glucose intoleran*") OR (maternal NEAR/2 "insulin resist*") OR
(hyperglycemia NEAR/2 pregnan*) OR (hyperglycaemia NEAR/2 pregnan*) OR macrosomia OR GDM)) AND
Language=(English)
Table A9. Science Citation Index Expanded®
Database: Science Citation Index Expanded (SCI-EXPANDED) via Web of KnowledgeSM <1899–present>
Search Date: 9 October 2011
Results: 2,308
# 17
(#16 OR #15 OR #14) AND Language=(English)
# 16
(#9) AND Language=(English) AND Document Types=(Meeting OR Meeting Paper) AND Literature Type=(Meeting
Abstract OR Meeting Address OR Meeting Paper OR Meeting Poster OR Meeting Report OR Meeting Slide OR Meeting
Summary)
# 15
(#13 AND #9) AND Language=(English
# 14
(#12 AND #9) AND Language=(English
# 13
(TS=( CPG* OR "best practice*" OR "professional standard*" OR "standard of care" OR (practice NEAR/2
guideline*) OR (practice NEAR/2 recommendation*) OR (practice NEAR/2 statement) OR (position NEAR/2 guideline*) OR
A-13
(position NEAR/2 recommendation*) OR (position NEAR/2 statement) OR (consensus NEAR/2 guideline*) OR (consensus
NEAR/2 recommendation*) OR (consensus NEAR/2 statement))) AND Language=(English)
# 12
(#10 NOT #11) AND Language=(English)
# 11
(TS=(animal* OR rat OR rats OR mouse OR mice OR rodent* OR rabbit OR rabbits OR horse OR horses OR equine
OR veterinar* OR bovine OR cow OR cows OR pig OR pigs OR porcine)) AND Language=(English)
# 10
((TS=(randomized controlled trial* OR controlled clinical trial* OR research design OR placebo* OR random*) OR
TS=(cohort* OR longitude* OR prospectiv* OR retrospectiv* OR long term OR long-term OR longterm OR followup OR
"follow up" OR follow-up) AND TS=(study OR studies OR trial))) AND Language=(English)
#9
(#8 OR #4) AND Language=(English)
#8
(#7 AND #1) AND Language=(English)
#7
(#6 OR #5) AND Language=(English)
#6
TS= ((diet NEAR/2 therap*) OR (diet NEAR/2 restrict*) OR (diet NEAR/2 advice) OR "medical nutrition* therapy"
OR MNT OR lifestyle* OR life-style* OR ("blood glucose" NEAR self-monitor*) OR ("blood glucose" NEAR "self monitor*")
OR SMBG OR counsel* OR (induc* NEAR labour) OR (induc* NEAR labor) OR cesarean OR caesarean OR (pregnan* NEAR
outcome*))) AND Language=(English)
#5
TS= (intervention* OR treat* OR therap* OR sulfonylurea* OR antidiabet* OR anti-diabet* OR gliclazid* OR
glimepirid* OR glipizid* OR glyburid* OR tolbutamid* OR antidiabet* OR anti-diabet* OR insulin* OR glibenclamid* OR
acarbos*)) AND Language=(English)
#4
#3 AND #2 AND #1
#3
TS=("sensitivity and specificity" OR sensitiv* OR specific* OR "predictive value" OR (diagnos* NEAR error*) OR
"false negative" OR "false positive" OR accurac*)) AND Language=(English)
#2
TS=( "prenatal screen*" OR (glucose NEAR/3 tolerance) OR (glucose NEAR/3 intoleran*) OR (glucose NEAR/3
challenge*) OR OGTT OR GCT OR "fasting glucose" OR "risk factor* ")) AND Language=(English)
#1
TS= ((gestation* NEAR/2 diabet*) OR (gestation* NEAR/2 "glucose intoleran*") OR (gestation* NEAR/2 "insulin
resist*") OR (pregnan* NEAR/2 diabet*) OR (pregnan* NEAR/2 "glucose intoleran*") OR (pregnan* NEAR/2 "insulin resist*")
OR (maternal NEAR/2 diabet*) OR (maternal NEAR/2 "glucose intoleran*") OR (maternal NEAR/2 "insulin resist*") OR
(hyperglycemia NEAR/2 pregnan*) OR (hyperglycaemia NEAR/2 pregnan*) OR macrosomia OR GDM)) AND
Language=(English)
Table A10. Conference Proceedings Citation Index–Science
Database: Conference Proceedings Citation Index- Science [CPCI-S] via Web of ScienceSM <1990–present>
Search Date: 9 October 2011
Results: 562
# 17
(#16 OR #15 OR #14) AND Language=(English)
# 16
(#9) AND Language=(English) AND Document Types=(Meeting OR Meeting Paper) AND Literature Type=(Meeting
Abstract OR Meeting Address OR Meeting Paper OR Meeting Poster OR Meeting Report OR Meeting Slide OR Meeting
Summary)
# 15
(#13 AND #9) AND Language=(English
# 14
(#12 AND #9) AND Language=(English
# 13
(TS=( CPG* OR "best practice*" OR "professional standard*" OR "standard of care" OR (practice NEAR/2
guideline*) OR (practice NEAR/2 recommendation*) OR (practice NEAR/2 statement) OR (position NEAR/2 guideline*) OR
(position NEAR/2 recommendation*) OR (position NEAR/2 statement) OR (consensus NEAR/2 guideline*) OR (consensus
NEAR/2 recommendation*) OR (consensus NEAR/2 statement))) AND Language=(English)
# 12
(#10 NOT #11) AND Language=(English)
# 11
(TS=(animal* OR rat OR rats OR mouse OR mice OR rodent* OR rabbit OR rabbits OR horse OR horses OR equine
OR veterinar* OR bovine OR cow OR cows OR pig OR pigs OR porcine)) AND Language=(English)
# 10
((TS=(randomized controlled trial* OR controlled clinical trial* OR research design OR placebo* OR random*) OR
TS=(cohort* OR longitude* OR prospectiv* OR retrospectiv* OR long term OR long-term OR longterm OR followup OR
"follow up" OR follow-up) AND TS=(study OR studies OR trial))) AND Language=(English)
#9
(#8 OR #4) AND Language=(English)
#8
(#7 AND #1) AND Language=(English)
#7
(#6 OR #5) AND Language=(English)
#6
TS= ((diet NEAR/2 therap*) OR (diet NEAR/2 restrict*) OR (diet NEAR/2 advice) OR "medical nutrition* therapy"
OR MNT OR lifestyle* OR life-style* OR ("blood glucose" NEAR self-monitor*) OR ("blood glucose" NEAR "self monitor*")
OR SMBG OR counsel* OR (induc* NEAR labour) OR (induc* NEAR labor) OR cesarean OR caesarean OR (pregnan* NEAR
outcome*))) AND Language=(English)
#5
TS= (intervention* OR treat* OR therap* OR sulfonylurea* OR antidiabet* OR anti-diabet* OR gliclazid* OR
glimepirid* OR glipizid* OR glyburid* OR tolbutamid* OR antidiabet* OR anti-diabet* OR insulin* OR glibenclamid* OR
acarbos*)) AND Language=(English)
#4
#3 AND #2 AND #1
#3
TS=("sensitivity and specificity" OR sensitiv* OR specific* OR "predictive value" OR (diagnos* NEAR error*) OR
"false negative" OR "false positive" OR accurac*)) AND Language=(English)
A-14
#2
TS=( "prenatal screen*" OR (glucose NEAR/3 tolerance) OR (glucose NEAR/3 intoleran*) OR (glucose NEAR/3
challenge*) OR OGTT OR GCT OR "fasting glucose" OR "risk factor* ")) AND Language=(English)
#1
TS= ((gestation* NEAR/2 diabet*) OR (gestation* NEAR/2 "glucose intoleran*") OR (gestation* NEAR/2 "insulin
resist*") OR (pregnan* NEAR/2 diabet*) OR (pregnan* NEAR/2 "glucose intoleran*") OR (pregnan* NEAR/2 "insulin resist*")
OR (maternal NEAR/2 diabet*) OR (maternal NEAR/2 "glucose intoleran*") OR (maternal NEAR/2 "insulin resist*") OR
(hyperglycemia NEAR/2 pregnan*) OR (hyperglycaemia NEAR/2 pregnan*) OR macrosomia OR GDM)) AND
Language=(English)
Table A11. LILACS (Latin American and Caribbean Health Science Literature)
Database: LILACS (Latin American and Caribbean Health Science Literature) <1982–current>
Search Date: 14 October 2011
Results: 236
1. gestational diabet$ AND (screening OR diagnos$)
2. maternal diabet$ AND (screening OR diagnos$)
3. gestational diabet$ AND (treating or treatment$ or therapy or therapies)
4. maternal diabet$ AND (treating or treatment$ or therapy or therapies)
Table A12. OCLC PapersFirst and PapersFirst
Databases:
ProceedingsFirst
PapersFirst
Search Date: 16 October 2011
Results:
ProceedingsFirst: 138; PapersFirst: 102
(kw: gestation* w2 diabet* OR kw: gestation* w2 glucose w intoleran* OR kw: gestation* w2 insulin w resist* OR kw:
pregnan* w2 diabet* OR kw: pregnan* w2 glucose w intoleran* OR kw: pregnan* w2 insulin w resist* OR kw: maternal w2
diabet* OR kw: maternal w2 glucose w intoleran* OR kw: maternal w2 insulin w resist* OR kw: hyperglycemia w2 pregnan*
OR kw: hyperglycaemia w2 pregnan* OR kw: macrosomia OR kw: GDM) and ((kw: prenatal w screen* OR kw: glucose w3
tolerance OR kw: glucose w3 intoleran* OR kw: glucose w3 challenge* OR kw: OGTT OR kw: GCT OR kw: fasting w glucose
OR kw: risk w factor*) or ((kw: intervention* OR kw: treat* OR kw: therap* OR kw: sulfonylurea* OR kw: antidiabet* OR kw:
anti-diabet* OR kw: gliclazid* OR kw: glimepirid* OR kw: glipizid* OR kw: glyburid* OR kw: tolbutamid* OR kw: antidiabet*
OR kw: anti-diabet* OR kw: insulin* OR kw: glibenclamid* OR kw: acarbos*) or (kw: diet w2 therap* OR kw: diet w2 restrict*
OR kw: diet w2 advice OR kw: medical w nutrition* w therapy OR kw: MNT OR kw: lifestyle* OR kw: life-style* OR kw:
blood w glucose w self-monitor* OR kw: blood w glucose w self w monitor* OR kw: SMBG OR kw: counsel* OR kw: induc* w
labour OR kw: induc* w labor OR kw: cesarean OR kw: caesarean OR kw: pregnan* w outcome*)))
Table A13. PubMed
Database: PubMed via NLM <last 180 days from 9 October 2011>
Search Date: 9 October 2011
Results: 377
#46 #39 NOT #45
#45 animal[TI] OR rat[TI] OR rats[TI] OR mouse [TI] OR mice[TI] OR rodent*[TI] OR rabbit*[TI] OR horse*[TI] OR
horses[TI] veterinar*[TI] OR cattle[TI] OR bovine[TI] OR cow[TI] OR cows[TI] OR swine[TI] OR pig[TI] OR pigs[TI] OR
porcine[TI]
#39 #21 OR #37 Limits: English, published in the last 180 days
#38 #21 OR #37
#37 #7 and #36
#36 #22 OR #23 OR #25 OR #28 OR #30 OR #31 OR #32 OR #33 OR #34 OR #34
#35 pregnanc* outcome*
#34 cesarean OR caesarean
#33 ((induc* AND labour) OR (induc* AND labor))
#32 counsel*
#31 SMBG
#30 ((self monitor* OR self-monitor*) AND blood glucose)
#28 (blood glucose AND (self monitor* OR self-monitor*))
#25 lifestyle OR life-style
#24 diet therap* OR diet* restrict* OR diet* advice OR medical nutrition therapy OR MNT
#23 sulfonylurea* OR gliclazid* OR glimepirid* OR glipizid* OR glyburid* OR tolbutamid* OR antidiabet* OR anti-diabet*
OR insulin* OR glibenclamid* OR acarbos*
#22 intervention* OR treating OR treatment? OR therapy OR therapies OR manage* OR monitor*
A-15
#21 #7 AND #16 AND #20
#20 #17 OR #18 OR #19
#19 reference standard* OR reference value*
#18 ROC OR "receiver operating characteristic"
#17 specific* OR sensitiv* OR predictive value OR accurac* OR diagnostic error*
#16 #8 OR #9 OR #10 OR #11 OR #12 OR #13 OR #14 OR #15
#15 fasting glucose
#14 OGTT OR GCT
#13 (glucose AND (tolerance OR intolerance OR challenge))
#12 risk factor*
#11 blood glucose
#10 ((prenatal OR early) AND diagnosis)
#9 screen*
#8 mass screening[MeSH Terms]
#7 #1 OR #2 OR #3 OR #4 OR #5 OR #6
#6 macrosomia
#5 ((hyperglycaemia OR hyperglycemia) AND pregnan*)
#4 (maternal AND (diabetic* OR diabete* OR DM OR glucose intoleran* OR insulin resistan*))
#3 (pregnan* AND (diabetic* OR diabete* OR DM OR glucose intoleran* OR insulin resistan*))
#2 (gestation* AND (diabetic* OR diabete* OR DM OR glucose intoleran* OR insulin resistan*))
#1 GDM
Table A14. Clinical Trials.gov and WHO
Databases:
ClinicalTrials.gov <1987 to February week 3 2012>
WHO International Clinical Trials Registry
Search Date: 23 February 2012
Results: 200
((asperger) OR (autistic disorder) OR autism OR schizophrenia OR (bipolar disorder) OR (depression) OR (bipolar disorder) OR
(obsessive-compulsive) OR (post-traumatic) OR (anorexia nervosa) OR anorexia) AND (antipsychotics) AND (child OR
adolescent OR pediatric OR infant) AND PDN(>1/1/1987) AND PDN(<12/31/2010)
A-16
Appendix B. Review Forms
B1. Screening Criteria for Key Questions 1-5
B2. Eligibility Criteria for Key Questions 1-5
B3. Methodological Quality Assessment by Study Design
a. Diagnostic studies – QUADAS-2 Tool
b. Randomized controlled trials – Cochrane Collaboration’s tool for assessing risk of bias
c. Cohort studies – Newcastle-Ottawa Quality Assessment Scale
B4. Data Extraction Forms
a.
b.
c.
d.
Screening and diagnosing gestational diabetes – key question 1
Screening and diagnosing gestational diabetes – key question 2
Screening and diagnosing gestational diabetes – key question 3
Screening and diagnosing gestational diabetes – key question 4 and 5
B-1
B1. Screening Criteria for Key Questions 1-5
1. Primary Research
Yes
No
Unclear
2. Published in English language
Yes
No
Unclear
3. Published from 1995 onward
Yes
No
Unclear
4. Must have a comparison group
(i.e., RCT, NRCT, R or P cohort, case control)
Yes
No
Unclear
5. Population: Pregnant women
Yes
No
Unclear
6. Intervention: Using any GDM screening or diagnostic approach,
(e.g., 1-step, 2-step, or other); and/or
Any treatment for GDM (e.g., dietary advice, blood glucose
monitoring, insulin therapy)
Yes
No
Unclear
Notes for screeners:
1. Mark each study as “no” [exclude], “unclear” or “yes” [retrieve full text] based on the
criteria above.
2. FLAG any relevant systematic reviews or meta-analyses using the code “sr”.
3. FLAG any studies that may be useful for background information with the code “bkg”.
Key words have been colour-coded and will appear in a different font. Here is an index of the
colouring:
Green population (e.g., gestational diabetes, pregnancy)
Purple treatments (e.g., diet, insulin, blood glucose monitoring, antidiabetic)
Aqua screening-related terms (e.g., screening, diagnosis, sensitivity, specificity,
positive predictive value, negative predictive value)
Orange specific tests (e.g., glucose tolerance test, glucose challenge test, glucose
screening test, diagnostic threshold)
Blue study designs (e.g., randomized, controlled trial, cohort, case control)
B-2
B2. Eligibility Criteria for Key Questions 1-5
INCLUSION / EXCLUSION FORM
Reviewer:
Ref ID:
CRITERIA
Yes
No
Unclear
1. PUBLICATION TYPE
a) Report of primary research
b) Full report available (Exclude abstracts and conference proceedings)
c) English language
d) Published in 1995 onward
2. STUDY DESIGN
a) Comparative study design (2 or more groups); one of:
i.
RCT
ii.
NRCT
iii.
Prospective or retrospective cohort studies (with concurrent or
nonconcurrent/historical control groups)
3. POPULATION
a) Pregnant women (any duration of gestation); Exclude if >20% of enrolled
women had known pre-existing diabetes and no subgroup analysis
4. INTERVENTION
a) Evaluating any GDM screening or diagnostic approach, (KQ1 & 2) or
screening / diagnostic threshold (KQ3) and/or
b) Evaluating any treatment for GDM (KQ4 & 5)
5. COMPARATORS
One or more of the following:
a) Any reference standard, other screening / diagnostic test, or criteria (KQ1)
[note: can also be a risk-factor if used for screening];
b) No screening / diagnostic test for GDM (KQ2);
c) Patients meeting different screening / diagnostic threshold for GDM (e.g.,
GDM vs. no GDM) (KQ3);
d) Placebo or no treatment (KQ4 & 5)
Exclude studies that compare 2 or more treatment, but have no placebo,
standard care or no treatment group
6. OUTCOME
Any one or more of the following:
a) Test properties (i.e., sensitivity, specificity, predictive values, accuracy; not
yield only);
b) Maternal outcomes:
i.
Short-term: preeclampsia/maternal hypertension, cesarean delivery,
depression, birth trauma, mortality, weight gain, other morbidity
ii.
Long-term: Type 2 DM risk, obesity, hypertension
c) Fetal/neonatal/child outcomes:
i.
Short-term: macrosomia, shoulder dystocia, clavicular fracture,
brachial plexus injury, birth injury, hypoglycemia, hyperbilirubinemia,
mortality, other morbidity
ii.
Long-term: obesity, type 2 DM, transgenerational GDM
d) Any adverse events or harms of screening or treatment (e.g., anxiety, healthcare
system issues, burden on practitioner’s office, increased interventions,
postpartum depression, small for gestational age, costs, resource allocations)
Comments:
REVIEWER’S DECISION : Include
Exclude
Unsure
RELEVANT TO QUESTION(S): KQ1
KQ2
KQ3
B-3
KQ4
KQ5
B3. Methodological Quality
a. QUADAS-2 Checklist (Diagnostic Studies)
Item
Assessment
1. Patient Selection
a. Was a consecutive or random sample of patients enrolled?
Support for judgment
b. Did the study avoid inappropriate exclusions?
Support for judgment
c. Was the study a low risk of bias?
d. Is the study applicable to the review?
Support for judgment
2. Index Test
a. Were the index test results interpreted without knowledge of the results of the
reference standard?
Support for judgment
b. If a threshold was used, was it pre-specified?
Support for judgment
c. Was the study a low risk of bias?
d. Is the study applicable to the review?
Support for judgment
3. Reference Standard
a. Is the reference standard likely to correctly classify the target audience?
Support for judgment
b. Were the reference standard results interpreted without knowledge of the results of
the index test?
Support for judgment
c. Was the study a low risk of bias?
d. Is the study applicable to the review?
Support for judgment
4. Flow and Timing
a. Was there an appropriate interval between the index test and reference standard?
Support for judgment
b. Did all patients receive the same reference standard?
Support for judgment
c. Were all patients included in the analysis?
Support for judgment
d. Was the study a low risk of bias?
B-4
b. The Cochrane Collaboration’s tool for assessing risk of bias (randomized controlled trials)
Domain
Description
Review authors’ judgment
Random sequence generation
Was the allocation sequence adequately generated?
Allocation concealment
Was allocation adequately concealed?
Blinding of participants and
personnel
Subjective outcomes
Was knowledge of the allocated intervention adequately
prevented during the study?
Subjective:
Objective:
Objective outcomes
Blinding of outcome assessment
Subjective outcomes
Was knowledge of the allocated intervention adequately
prevented during the study?
Subjective:
Objective:
Objective outcomes
Incomplete outcome data,
Outcome:
Subjective outcomes
Were incomplete outcome data adequately addressed?
Subjective:
Objective outcomes
Objective:
Selective outcome reporting
Are reports of the study free of suggestion of selective
outcome reporting?
Other sources of bias
Was the study apparently free of other problems that could
put it at a high risk of bias?
Overall risk of bias
Subjective outcomes
Objective outcomes
B-5
c. Newcastle-Ottawa Quality Assessment Scale (Cohort Studies)
Selection
1) Representativeness of the exposed cohort (i.e., glucose intolerant or GDM patients)
a) truly representative of the average patient with glucose intolerance in the community *
b) somewhat representative of the average glucose intolerance in the community *
c) selected group of users eg nurses, volunteers
d) no description of the derivation of the cohort
2) Selection of the non-exposed cohort (i.e., normal or minimal glucose intolerant patients)
a) drawn from the same community as the exposed cohort *
b) drawn from a different source
c) no description of the derivation of the non exposed cohort
3) Ascertainment of exposure
a) secure record (eg surgical records) *
b) structured interview *
c) written self report
d) no description
4) Demonstration that outcome of interest was not present at start of study
a) yes *
b) no
Comparability
1) Comparability of cohorts on the basis of the design or analysis
a) study controls for age, race/ethnicity, weight/BMI, previous GDM, or family history of diabetes **
b) study controls for any additional factor *
Outcome
1) Assessment of outcome
a) independent blind assessment *
b) record linkage *
c) self report
d) no description
2) Was follow-up long enough for outcomes to occur
a) yes (follows patients at least until birth) *
b) no
3) Adequacy of follow up of cohorts
a) complete follow up - all subjects accounted for *
b) subjects lost to follow up unlikely to introduce bias: small number lost (>90% follow up), or
description provided of those lost *
c) follow up rate <75% and no description of those lost
d) no statement
TOTAL STARS (0-9)
Note: A study can be awarded a maximum of one star for each numbered item within the Selection and
Outcome categories. A maximum of two stars can be given for Comparability
B4. Data Extraction
B-6
a. Screening and Diagnosing Gestational Diabetes – Key Question 1
I.
Coder Information
RefID:
First Author:
DE initials:
DV initials:
Year:
Other KQs:
2;
3;
4;
5
II.
Study Characteristics
Country:
Publication type:
Centers:
Recruitment start date (e.g., Jan 1998):
Funding:
Industry;
Government;
Study design:
Recruitment end date (e.g., Feb
2000):
Foundation;
No funding;
Other;
ND
Academic;
If industry, specify firm*:
Blinding to test result:
* Use “NR” if not reported
III.
Selection Criteria and Testing Conditions
Inclusion criteria:
If “other,” specify*:
Duration of followup:
Exclusion criteria:
Exclude pre-pregnancy (type 1, 2)?
Exclude overt diabetes diagnosed during
pregnancy?
Did patients routinely undergo early testing for overt diabetes during pregnancy?
Patients Enrolled Consecutively:
Comparisons Done:
Matched Study (all comparator tests performed in all patients)
Random (comparator tests done in different patients)
Yes
No
ND
Non-Random (comparator tests in different patients, select gp)
Reference standard reported?
If so, specify:
B-7
IV. Screening and Diagnostic Tests
GCT/GST?
OGTT?
Index test? :
Pre-test protocol (fast/diet):
Index test? :
Pre-test protocol (fast/diet):
Test Intervals:
Fasting;
1 hr;
2 hr;
3
hr
Glucose load:
Time of test (wks):
Criteria:
ADA, year:
CC, year:
NDDG, year:
WHO, year:
Other1: , year:
Other2: , year:
NR
Brand of beverage*:
Amount of liquid*:
Brand of Glucose meter:
Manufacturing company:
Plasma glucose estimation method:
Manufacturing company:
Central lab?
Test Intervals:
Fasting;
1 hr;
hr
Glucose load:
Time of test (wks):
Criteria:
ADA, year:
CC, year:
NDDG, year:
WHO, year:
Other1: , year:
Other2: , year:
NR
Brand of beverage*:
Amount of liquid*:
2 hr;
Other test 1?
Specify:
Index test? :
Pre-test protocol (fast/diet):
3
Other test 2?
Specify:
Index test? :
Pre-test protocol (fast/diet):
Test Intervals:
Test Intervals:
Fasting;
1 hr;
2 hr;
3
Fasting;
1 hr;
hr
hr
Glucose load:
Glucose load:
Time of test (wks):
Time of test (wks):
Criteria:
Criteria:
ADA, year:
ADA, year:
CC, year:
CC, year:
NDDG, year:
NDDG, year:
WHO, year:
WHO, year:
Other1: , year:
Other1: , year:
Other2: , year:
Other2: , year:
NR
NR
Brand of beverage*:
Brand of beverage*:
Amount of liquid*:
Amount of liquid*:
Measurements performed by trained staff?
Notes:
*If not reported, use NR
B-8
2 hr;
3
V.
Study Arms
Group 1
Group 2
Group label
GCT: Fasting
±
±
GCT: 1hr
±
±
GCT: 2hr
±
±
GCT:3hr
±
±
OGTT: Fasting
±
±
OGTT: 1hr
±
±
OGTT: 2hr
±
±
OGTT: 3hr
±
±
Treatment status
Glucose levels reported in the following units:
mg/dL;
mmol/L
Are groups mutually exclusive?
Baseline Characteristics
Group 1
Group 2
Pts enrolled, n
Pts analyzed, n
Withdrawals, n
Age (yr),
±
±
mean ± SD
median ± IQR
Prepregn. weight,
±
±
lb;
kg
mean ± SD
median ± IQR
BMI,
±
±
mean±SD
median ± IQR
SBP (mmHg),
±
±
mean ± SD
median ± IQR
Group 1
Group 2
White, n
Black, n
Hispanic, n
Asian, n
Other, n
Gestation at time
±
±
of test (wk)
mean ± SD
median ± IQR
Smoking, n
Alcohol use, n
Family history of
Group 3
Group 4
TOTAL
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
Glucose levels reported as:
median ± IQR
mean ± SD;
I.
Group 3
Group 4
TOTAL
±
±
±
±
±
±
±
±
±
±
±
±
Group 3
Group 4
TOTAL
±
±
±
B-9
diabetes, n
History of GDM,
n
Parity, n
Parity
mean ± SD
median ± IQR
Comorbidities, n
0
1
≥2
0
1
≥2
±
0
1
≥2
±
0
1
≥2
±
Comments
II.
Conclusions
Briefly paraphrase the author conclusions:
REFERENCES TO BE CHECKED:
ASSOCIATED PUBLICATIONS (list all separated by semi-colons):
B-10
0
1
≥2
±
±
b. Screening and Diagnosing Gestational Diabetes – Key Question 2
IV.
Coder Information
RefID:
First Author:
DE initials:
DV initials:
Year:
Other KQs:
1;
3;
4;
V.
Study Characteristics
Country:
Publication type:
Centers:
Recruitment start date (e.g., Jan 1998):
Funding:
Industry;
Government;
Study design:
Recruitment end date (e.g., Feb
2000):
Foundation;
No funding;
Other;
ND
Academic;
If industry, specify firm*:
Blinding to test result:
* Use “NR” if not reported
VI.
Study Eligibility Criteria
Inclusion criteria:
5
If “other,” specify*:
Duration of followup:
Exclusion criteria:
Exclude pre-pregnancy (type 1, 2)?
Exclude overt diabetes diagnosed during
pregnancy?
Did patients routinely undergo early testing for overt diabetes during pregnancy?
VII.
Screening and Diagnostic Tests
GCT/GST?
OGTT?
Test intervals:
Test intervals:
Fasting;
1 hr;
2 hr;
Fasting;
1 hr;
3 hr
3 hr
Glucose load:
Glucose load:
Time of test (wks):
Time of test (wks):
Criteria:
Criteria:
ADA, year:
ADA, year:
CC, year:
CC, year:
NDDG, year:
NDDG, year:
WHO, year:
WHO, year:
Other1: , year:
Other1: , year:
Other2: , year:
Other2: , year:
NR
NR
Central lab?
Notes:
B-11
2 hr;
Specify:
Other test?
Test intervals:
Fasting;
1 hr;
2 hr;
3 hr
Glucose load:
Time of test (wks):
Criteria:
ADA, year:
CC, year:
NDDG, year:
WHO, year:
Other1: , year:
Other2: , year:
NR
VIII.
Study Arms
Group 1
Group 2
Group label
GCT: Fasting
±
±
GCT: 1 hr
±
±
GCT: 2 hr
±
±
GCT: 3 hr
±
±
OGTT: Fasting
±
±
OGTT: 1 hr
±
±
OGTT: 2 hr
±
±
OGTT: 3 hr
±
±
Treatment status
Glucose levels reported in the following units:
Are groups mutually exclusive?
Baseline Characteristics
Group 1
Pts enrolled, n
Pts analyzed, n
Withdrawals, n
Age (yr),
±
mean ± SD
median ± IQR
Prepregn. weight,
±
lb;
kg
mean ± SD
median ± IQR
BMI,
±
mean±SD
median ± IQR
SBP (mmHg),
±
mean ± SD
median ± IQR
Group 1
Group 3
Group 4
Group 5
Group 6
Group 7
TOTAL
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
mean ± SD;
median ± IQR
mg/dL;
mmol/L
Glucose levels reported as:
IX.
Group 2
Group 3
Group 4
Group 5
Group 6
Group 7
TOTAL
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
Group 2
Group 3
Group 4
Group 5
Group 6
Group 7
TOTAL
B-12
White, n
Black, n
Hispanic, n
Asian, n
Other, n
Gestation at time
of test (wk)
mean ± SD
median ± IQR
Smoking, n
Alcohol use, n
Family history of
diabetes, n
History of GDM,
n
Parity, n
Parity
mean ± SD
median ± IQR
Comorbidities, n
±
0
1
≥2
±
0
1
≥2
±
±
0
1
≥2
±
±
0
1
≥2
±
±
0
1
≥2
±
Comments
B-13
±
0
1
≥2
±
±
0
1
≥2
±
±
0
1
≥2
±
±
X.
Conclusions
Briefly paraphrase the author conclusions:
REFERENCES TO BE CHECKED:
ASSOCIATED PUBLICATIONS (list all separated by semi-colons):
B-14
c. Screening and Diagnosing Gestational Diabetes – Key Question 3
I.
Coder Information
RefID:
First Author:
DE initials:
DV initials:
Year:
Other KQs:
1;
2;
4;
II.
Study Characteristics
Country:
Publication type:
Centers:
Recruitment start date (e.g., Jan 1998):
Funding:
Industry;
Government;
Study design:
Recruitment end date (e.g., Feb
2000):
Foundation;
No funding;
Other;
ND
Academic;
If industry, specify firm*:
Blinding to test result:
* Use “NR” if not reported
III.
Study Eligibility Criteria
Inclusion criteria:
5
If “other,” specify*:
Duration of followup:
Exclusion criteria:
Exclude pre-pregnancy (type 1, 2)?
Exclude overt diabetes diagnosed during
pregnancy?
Did patients routinely undergo early testing for overt diabetes during pregnancy?
IV.
Screening and Diagnostic Tests
GCT/GST?
OGTT?
Test intervals:
Test intervals:
Fasting;
1 hr;
2 hr;
Fasting;
1 hr;
3 hr
3 hr
Glucose load:
Glucose load:
Time of test (wks):
Time of test (wks):
Criteria:
Criteria:
ADA, year:
ADA, year:
CC, year:
CC, year:
NDDG, year:
NDDG, year:
WHO, year:
WHO, year:
Other1: , year:
Other1: , year:
Other2: , year:
Other2: , year:
NR
NR
Central lab?
Notes:
B-15
2 hr;
Specify:
Other test?
Test intervals:
Fasting;
1 hr;
2 hr;
3 hr
Glucose load:
Time of test (wks):
Criteria:
ADA, year:
CC, year:
NDDG, year:
WHO, year:
Other1: , year:
Other2: , year:
NR
V.
Study Arms
Group 1
Group 2
Group label
GCT: Fasting
±
±
GCT: 1 hr
±
±
GCT: 2 hr
±
±
GCT: 3 hr
±
±
OGTT: Fasting
±
±
OGTT: 1 hr
±
±
OGTT: 2 hr
±
±
OGTT: 3 hr
±
±
Treatment status
Glucose levels reported in the following units:
Are groups mutually exclusive?
Baseline Characteristics
Group 1
Pts enrolled, n
Pts analyzed, n
Withdrawals, n
Age (yr),
±
mean ± SD
median ± IQR
Prepregn. weight,
±
lb;
kg
mean ± SD
median ± IQR
BMI,
±
mean±SD
median ± IQR
SBP (mmHg),
±
mean ± SD
median ± IQR
Group 1
Group 3
Group 4
Group 5
Group 6
Group 7
TOTAL
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
mean ± SD;
median ± IQR
mg/dL;
mmol/L
Glucose levels reported as:
VI.
Group 2
Group 3
Group 4
Group 5
Group 6
Group 7
TOTAL
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
Group 2
Group 3
Group 4
Group 5
Group 6
Group 7
TOTAL
B-16
White, n
Black, n
Hispanic, n
Asian, n
Other, n
Gestation at time
of test (wk)
mean ± SD
median ± IQR
Smoking, n
Alcohol use, n
Family history of
diabetes, n
History of GDM,
n
Parity, n
Parity
mean ± SD
median ± IQR
Comorbidities, n
±
0
1
≥2
±
0
1
≥2
±
±
0
1
≥2
±
±
0
1
≥2
±
±
0
1
≥2
±
Comments
B-17
±
0
1
≥2
±
±
0
1
≥2
±
±
0
1
≥2
±
±
VII.
Conclusions
Briefly paraphrase the author conclusions:
REFERENCES TO BE CHECKED:
ASSOCIATED PUBLICATIONS (list all separated by semi-colons):
B-18
d. Screening and Diagnosing Gestational Diabetes Mellitus – Key Question 4 and 5
I.
Ref ID:
Coder Information
First Author:
DE Initials:
DE Reviewer Initials:
II.
Study Characteristics
Country:
Centers:
Funding:
Year of Publication:
Industry;
Government;
Other KQs:
1;
3
Publication Type:
Study Design:
Recruitment start date (e.g.
Jan. 2001):
Recruitment end date (e.g.
Feb. 2000):
Academic;
Foundation;
No funding;
If Industry, specify firm:*
If "Other", specify*:
Blinding to test result:
Duration of followup:
*use NR if not reported
III.
Study Eligibility Criteria
Inclusion Criteria:
2;
Other;
ND
Exclusion Criteria:
Exclude pre-pregnancy diabetes (type 1, 2)?
Exclude overt diabetes diagnosed during pregnancy?
Did patients routinely undergo early testing for overt diabetes during pregnancy?
IV.
Screening and Diagnostic Tests
GCT/GST?
OGTT?
Test intervals:
Test intervals:
Fasting;
1 hr;
2 hr;
Fasting;
1 hr;
3 hr
3 hr
Glucose load:
Glucose load:
Time of test (wks):
Time of test (wks):
Criteria:
Criteria:
ADA, year:
ADA, year:
CC, year:
CC, year:
NDDG, year:
NDDG, year:
WHO, year:
WHO, year:
Other1: , year:
Other1: , year:
Other2: , year:
Other2: , year:
NR
NR
Central lab?
Notes:
B-19
2 hr;
Specify:
Other test?
Test intervals:
Fasting;
1 hr;
2 hr;
3 hr
Glucose load:
Time of test (wks):
Criteria:
ADA, year:
CC, year:
NDDG, year:
WHO, year:
Other1: , year:
Other2: , year:
NR
V.
Study Arms
Group 1
Group 2
Group label
GCT: Fasting
±
±
GCT: 1hr
±
±
GCT: 2hr
±
±
GCT:3hr
±
±
OGTT: Fasting
±
±
OGTT: 1hr
±
±
OGTT: 2hr
±
±
OGTT: 3hr
±
±
Treatment status
Glucose levels reported in the following units:
mg/dL;
mmol/L
Are groups mutually exclusive?
VI.
Intervention
Group 1
Study arm label
Brief description of
intervention
Care provider(s)
BG target: FGB
BG target: 1 hr
Dietary counseling/
advice?
Formal diet plan?
If formal diet,
describe:
Involve dietician/
nutritionist?
BG monitoring?
Frequency of BG
monitoring
BGM device
Insulin?
Oral medications?
Drug name
BG values for
prescription:
Dosing
Daily dosage
Other tx
Rules for tx/dose
adjustment
Group 3
Group 4
TOTAL
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
Glucose levels reported as:
median ± IQR
Group 2
Group 3
mean ± SD;
Group 4
Units:
Units:
Units:
Units:
Units:
Units:
Units:
Units:
x per
x per
x per
x per
≥ Units:
Time:
≥ Units:
Time:
≥ Units:
Time:
≥ Units:
Time:
Units:
Units:
Units:
Units:
B-20
Comments
VII.
Baseline Characteristics
Group 1
Pts enrolled, n
Pts analyzed, n
Withdrawals, n
Age (yr)
±
mean ± SD
median ± IQR
Prepregn. weight,
±
lb;
kg
mean ± SD
median ± IQR
BMI,
±
mean±SD
median ± IQR
SBP (mmHg),
±
mean ± SD
median ± IQR
White, n
Black, n
Hispanic, n
Asian, n
Other, n
Gestation at time
±
of test (wk)
mean ± SD
median ± IQR
Smoking, n
Alcohol use, n
Family history of
diabetes, n
History of GDM,
n
Parity, n
0
1
≥2
Parity
±
mean ± SD
median ± IQR
Overt diabetes, n
Comorbidities, n
Group 2
Group 3
Group 4
TOTAL
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
0
1
≥2
0
1
≥2
±
0
1
≥2
±
B-21
0
1
≥2
±
±
Comments
VIII. Conclusions
Briefly paraphrase author conclusions:
REFERENCES TO BE CHECKED:
ASSOCIATED PUBLICATIONS (list all separated by semi-colons):
B-22
Appendix C. Methodological Quality of Included
Studies
Table C1. Methodological quality of diagnostic studies using QUADAS-2 for Key Question 1
Table C2. Methodological quality of randomized controlled trials (RCTs) using the Cochrane
Collaboration’s tool for assessing risk of bias for Key Questions 2 to 5
Table C3. Methodological quality of prospective cohort studies (PCS) and retrospective cohort
studies (RCS) using Newcastle-Ottawa Quality Assessment Scale, by Key Question
and design
C-1
Table C1. Methodological quality of diagnostic studies using QUADAS-2 for Key Question 1
d. applicable
a. likely to
classify
b. index results
not known
c. low risk of
bias
d. applicable
a. interval
b. same
standard
c. all included
in analysis
d. low risk of
bias
Flow and Timing*
c. low risk of
bias
4.
b. threshold
Reference Standard*
a. reference
results not
known
3.
d. applicable
Index Test*
c. low risk of
bias
Agarwal, 2000
PCS
Agarwal, 2001
PCS (34426)
Agarwal, 2005a
PCS
Agarwal, 2005b
PCS
Agarwal, 2006
PCS
Agarwal, 2008
PCS
Agarwal, 2011
PCS
Ardawi, 2000
PCS
Ayach, 2006
PCS
Balaji(1), 2011
PCS
Balaji(2), 2011
PCS
Berkus, 1995
PCS
Bobrowski, 1996
PCS
Brustman, 1995
PCS
2.
b. exclusion
Author, Year
Study design
Patient Selection*
a. sample
1.
No
Yes
No
No
U
U
U
Yes
Yes
U
U
Yes
U
Yes
Yes
U
No
Yes
No
No
U
Yes
U
Yes
Yes
U
U
Yes
U
Yes
Yes
U
Yes
U
U
No
U
Yes
U
Yes
Yes
U
U
Yes
U
Yes
Yes
U
Yes
Yes
Yes
No
U
Yes
U
Yes
Yes
U
U
Yes
U
Yes
Yes
U
Yes
Yes
Yes
No
U
U
U
Yes
Yes
U
U
Yes
U
Yes
Yes
U
Yes
No
U
No
U
Yes
U
Yes
Yes
U
U
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
U
U
U
U
Yes
U
U
Yes
Yes
Yes
Yes
Yes
Yes
U
U
No
Yes
Yes
Yes
Yes
Yes
No
No
Yes
Yes
Yes
U
U
Yes
No
No
No
Yes
Yes
Yes
Yes
Yes
U
U
Yes
Yes
Yes
U
U
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
U
Yes
U
Yes
U
Yes
U
Yes
Yes
Yes
U
U
No
Yes
No
Yes
U
Yes
U
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
No
Yes
U
Yes
U
Yes
Yes
U
U
Yes
U
Yes
Yes
U
No
Yes
No
Yes
U
Yes
U
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
C-2
d. applicable
a. likely to
classify
b. index results
not known
c. low risk of
bias
d. applicable
a. interval
b. same
standard
c. all included
in analysis
d. low risk of
bias
Flow and Timing*
c. low risk of
bias
4.
b. threshold
Reference Standard*
a. reference
results not
known
Chevalier, 2011
PCS
De los Monteros,
1999
PCS
Deerochanawong,
1996
PCS
Eslamian, 2008
PCS
Gandevani, 2011
PCS
Hill, 2005
PCS
Jakobi, 2003
PCS
Jensen, 2004
PCS
Kashi, 2007
PCS
Kauffman, 2006
PCS
Lamar, 1999
PCS
3.
d. applicable
Chastang, 2003
PCS
Index Test*
c. low risk of
bias
Buhling, 2004
PCS
Cetin, 1996
PCS
2.
b. exclusion
Author, Year
Study design
Patient Selection*
a. sample
1.
Yes
Yes
Yes
U
Yes
U
U
U
U
No
U
U
Yes
Yes
No
No
U
Yes
U
No
Yes
Yes
Yes
Yes
Yes
U
U
Yes
Yes
Yes
Yes
Yes
No
No
No
U
No
Yes
No
Yes
Yes
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
U
Yes
Yes
Yes
Yes
Yes
U
U
Yes
Yes
No
Yes
No
Yes
Yes
Yes
U
Yes
Yes
Yes
Yes
Yes
U
U
Yes
Yes
Yes
No
No
U
Yes
U
No
Yes
Yes
Yes
Yes
U
U
U
Yes
Yes
No
Yes
No
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
No
U
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
No
No
U
Yes
No
Yes
Yes
Yes
No
No
No
U
Yes
U
Yes
Yes
U
U
Yes
Yes
Yes
No
No
U
No
No
No
U
No
U
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
U
Yes
Yes
Yes
U
Yes
Yes
Yes
Yes
U
Yes
U
U
No
No
No
No
Yes
Yes
Yes
U
Yes
No
No
Yes
U
Yes
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
U
U
Yes
Yes
Yes
Yes
Yes
Yes
U
U
Yes
Yes
Yes
No
No
C-3
d. applicable
a. likely to
classify
b. index results
not known
c. low risk of
bias
d. applicable
a. interval
b. same
standard
c. all included
in analysis
d. low risk of
bias
Flow and Timing*
c. low risk of
bias
4.
b. threshold
Reference Standard*
a. reference
results not
known
3.
d. applicable
Index Test*
c. low risk of
bias
Maegawa, 2003
PCS
Mello, 2006
PCS
Moses, 2011
PCS
Ostlund, 2003
PCS
Perea-Carrasco,
2002
PCS
Perucchini, 1999
PCS
Poyhonen-Alho,
2004
PCS
Rajput, 2012
PCS
Reichelt, 1998
PCS
Rey, 2004
PCS
Rust, 1998
PCS
Sacks, 2003
PCS
Siribaddana, 2003
PCS
Soheilykhah, 2011
PCS
2.
b. exclusion
Author, Year
Study design
Patient Selection*
a. sample
1.
Yes
Yes
Yes
U
Yes
Yes
Yes
Yes
Yes
U
U
U
Yes
No
Yes
No
Yes
Yes
Yes
U
Yes
Yes
Yes
Yes
Yes
No
No
Yes
Yes
No
Yes
No
Yes
Yes
Yes
U
Yes
Yes
Yes
Yes
U
Yes
U
U
Yes
Yes
Yes
Yes
Yes
Yes
Yes
U
Yes
Yes
Yes
Yes
Yes
No
No
Yes
U
Yes
U
No
Yes
Yes
Yes
U
U
Yes
U
Yes
Yes
U
U
Yes
U
Yes
Yes
U
Yes
Yes
Yes
U
Yes
Yes
Yes
U
Yes
U
U
Yes
Yes
Yes
U
Yes
Yes
Yes
Yes
U
Yes
Yes
Yes
Yes
U
No
Yes
U
Yes
No
U
U
Yes
Yes
Yes
No
No
No
No
Yes
Yes
U
U
Yes
Yes
Yes
Yes
Yes
Yes
U
U
No
U
No
U
U
Yes
U
U
Yes
U
Yes
U
U
Yes
U
U
Yes
Yes
Yes
Yes
Yes
Yes
U
U
Yes
U
Yes
Yes
U
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
U
U
Yes
Yes
No
Yes
Yes
Yes
U
U
Yes
Yes
Yes
Yes
Yes
Yes
U
U
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
Yes
No
Yes
U
No
No
Yes
U
Yes
U
U
C-4
d. applicable
a. likely to
classify
b. index results
not known
c. low risk of
bias
d. applicable
a. interval
b. same
standard
c. all included
in analysis
d. low risk of
bias
Flow and Timing*
c. low risk of
bias
4.
b. threshold
Reference Standard*
a. reference
results not
known
3.
d. applicable
Index Test*
c. low risk of
bias
Soonthornpun,
2003
PCS
Tan, 2007
PCS
Trihospital 1998
PCS (Naylor)
Uncu, 1995
PCS
van Leeuwen 2007
PCS
Weerakiet, 2006
PCS
Wijeyaratne, 2006
PCS
Yachi, 2011
PCS
Yogev, 2004
PCS
2.
b. exclusion
Author, Year
Study design
Patient Selection*
a. sample
1.
No
U
No
No
U
Yes
U
Yes
Yes
U
U
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
U
Yes
U
Yes
Yes
U
U
Yes
Yes
No
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
U
U
U
No
Yes
Yes
U
Yes
Yes
U
U
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
U
Yes
Yes
Yes
Yes
Yes
No
No
Yes
Yes
U
Yes
U
Yes
Yes
Yes
No
U
No
No
U
Yes
U
U
Yes
Yes
Yes
Yes
Yes
Yes
U
U
No
Yes
U
U
U
Yes
Yes
Yes
Yes
Yes
U
Yes
U
U
Yes
U
U
Yes
Yes
Yes
U
Yes
U
U
U
No
No
Yes
Yes
U
Yes
U
Yes
Yes
Yes
Yes
Yes
Yes
No
U
Yes
Yes
U
Yes
U
*QUADAS domain descriptions: 1.a. Random or consecutive sample; 1.b. Did the study avoid inappropriate exclusions?; 1.c. Was the study a low risk of bias?; 1.d.Is the study
applicable?; 2.a. Reference standard results not known; 2.b. Pre specified threshold; 2.c. Was the study a low risk of bias?; 2.d. Is the study applicable?; 3.a. Likely to classify target
patients; 3.b. Index test results not known; 3.c. Was the study a low risk of bias?; 3.d. Is the study applicable?; 4.a. Interval between tests; 4.b. Same standard for all patients; 4.c. All
patients included in analysis; 4.d. Was the study a low risk of bias?
U = unclear
C-5
Table C2. Methodological quality of randomized controlled trials (RCTs) using the Cochrane Collaboration’s tool for assessing risk of
bias for Key Questions 2 to 5
Blinding
Author Year
Bevier,
1999
Bonomo,
2005
Crowther,
2005
Garner,
1997
Landon,
2009
Sequence
generation
Allocation
concealment
Unclear
Incomplete
outcome data*
Selective
outcome
reporting
Other
Participants*
Outcome
assessment*
Unclear
Unclear
Low
Unclear
Low
Low
Low
Unclear
Unclear
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Unclear
Unclear
Unclear
High
High
Low
Low
Unclear
Unclear
Low
Low
Low
Low
Low
* Domains for which assessments are made by outcome were assessed for objective outcomes
† Quality rating based on EPC Methods Guide (good, fair, poor)
C-6
Overall Risk of
Bias*
†
(quality rating)
Unclear
(fair)
Unclear
(fair)
Low
(good)
High
(poor)
Unclear
(fair)
Table C3. Methodological quality of prospective cohort studies (PCS) and retrospective cohort studies (RCS) using Newcastle-Ottawa
Quality Assessment Scale, by Key Question and design
Selection
of non-exposed
cohort
Ascertainment of
exposure
Outcome of
interest not
present at start of
study
known
factors*
additional
factor
Assessment of
outcome
Follow up long
enough for
outcomes to occur
Adequacy of
cohort follow up
Total stars
†
(quality rating)
KQ2 - PCS
Solomon, 1996
Representativeness of exposed
cohort
Author, Year
Comparability of
cohorts (Study
controls)
Selected
group of users
Same
community as
exposed cohort
Structured
interview
Yes
No
No
Record
linkage
Yes
Subjects lost
unlikely to
introduce bias
6
(fair)
Truly
representative
Same
community as
exposed cohort
Secure
record
Yes
No
No
Record
linkage
Yes
Complete
follow up
7
(good)
Secure
record
Yes
No
No
Record
linkage
Yes
Secure
record
Yes
No
No
No
description
Yes
Secure
record
Yes
Yes
Yes
No
description
Yes
Secure
record
Yes
Yes
Yes
Independent
blind
assessment
Yes
Secure
record
Yes
Yes
Yes
No
description
Yes
Secure
record
Yes
Yes
Yes
No
description
Yes
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
KQ2 - RCS
Chanprapaph,
2004
KQ3 – PCS
Ardawi, 2000
Truly
representative
Lao, 2001
Somewhat
representative
Lapolla, 2007
Truly
representative
Metzger/
HAPO, 2008
Truly
representative
Retnakaran,
2008
Somewhat
representative
Sacks, 1995
Somewhat
representative
Sermer, 1995
RCT
Somewhat
representative
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
C-7
Subjects lost
unlikely to
introduce bias
Subjects lost
unlikely to
introduce bias
Complete
follow up
Subjects lost
unlikely to
introduce bias
Subjects lost
unlikely to
introduce bias
Subjects lost
unlikely to
introduce bias
Subjects lost
unlikely to
introduce bias
7
(good)
6
(fair)
8
(good)
9
(good)
8
(good)
8
(good)
9
(good)
known
factors*
additional
factor
Assessment of
outcome
Follow up long
enough for
outcomes to occur
Adequacy of
cohort follow up
Total stars
†
(quality rating)
No
description
Yes
Subjects lost
unlikely to
introduce bias
8
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Complete
follow up
9
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Complete
follow up
9
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Subjects lost
unlikely to
introduce bias
9
(good)
Secure
record
Yes
No
No
Record
linkage
Yes
Complete
follow up
7
(good)
Secure
record
Yes
No
No
Record
linkage
Yes
Complete
follow up
7
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Complete
follow up
9
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Complete
follow up
9
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Complete
follow up
9
(good)
Secure
record
Yes
No
No
Record
linkage
Yes
Complete
follow up
7
(good)
Secure
record
Yes
No
No
Record
linkage
Yes
Complete
follow up
7
(good)
Outcome of
interest not
present at start of
study
Yes
Ascertainment of
exposure
Yes
Selection
of non-exposed
cohort
Shirazian,
2008
Representativeness of exposed
cohort
Author, Year
Comparability of
cohorts (Study
controls)
Somewhat
representative
Same
community as
exposed cohort
Secure
record
Yes
KQ3 - RCS
Aberg, 2001
Adams, 1998
Berggren,
2011
Truly
representative
Truly
representative
Truly
representative
Berkus, 1995
Somewhat
representative
Biri, 2009
Truly
representative
Black, 2010
Truly
representative
Bo, 2004
Somewhat
representative
Cheng, 2009
Truly
representative
Chico, 2005
Somewhat
representative
Chou, 2010
Somewhat
representative
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
C-8
Ascertainment of
exposure
Outcome of
interest not
present at start of
study
known
factors*
additional
factor
Assessment of
outcome
Follow up long
enough for
outcomes to occur
Adequacy of
cohort follow up
Total stars
†
(quality rating)
Selection
of non-exposed
cohort
Representativeness of exposed
cohort
Author, Year
Comparability of
cohorts (Study
controls)
Secure
record
Yes
No
No
Record
linkage
Yes
Complete
follow up
7
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Secure
record
Yes
Yes
Yes
Independent
blind
assessment
Yes
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Secure
record
Yes
No
No
Record
linkage
Yes
Subjects lost
unlikely to
introduce bias
7
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Complete
follow up
9
(good)
Secure
record
Yes
Yes
No
Record
linkage
Yes
Subjects lost
unlikely to
introduce bias
8
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Complete
follow up
9
(good)
Secure
record
Yes
No
No
Record
linkage
Yes
Complete
follow up
7
(good)
exposed cohort
Cok, 2011
Corrado, 2009
Somewhat
representative
Somewhat
representative
Hillier, 2007
Truly
representative
Jensen, 2002
Somewhat
representative
Kim, 2002
Somewhat
representative
Kwik, 2007
Truly
representative
Langer, 2005
Somewhat
representative
Lao, 2003
Somewhat
representative
Lapolla, 2011
Somewhat
representative
Morikawa,
2010
Somewhat
representative
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
C-9
Subjects lost
unlikely to
introduce bias
Subjects lost
unlikely to
introduce bias
Subjects lost
unlikely to
introduce bias
Subjects lost
unlikely to
introduce bias
9
(good)
9
(good)
9
(good)
8
(good)
Somewhat
representative
Vambergue,
2000
Truly
representative
Yang, 2002
Somewhat
representative
Selection
of non-exposed
cohort
Total stars
†
(quality rating)
Tan, 2008
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Adequacy of
cohort follow up
Somewhat
representative
Follow up long
enough for
outcomes to occur
Stamilio, 2004
Truly
representative
Assessment of
outcome
Schwartz,
1999
Somewhat
representative
additional
factor
Rust, 1996
Truly
representative
known
factors*
Ricart, 2005
Truly
representative
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Outcome of
interest not
present at start of
study
Pennison,
2001
Somewhat
representative
Ascertainment of
exposure
Nord, 1995
Representativeness of exposed
cohort
Author, Year
Comparability of
cohorts (Study
controls)
Secure
record
Yes
No
No
Record
linkage
Yes
Subjects lost
unlikely to
introduce bias
7
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Complete
follow up
9
(good)
Secure
record
Yes
No
No
Record
linkage
Yes
Complete
follow up
7
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Secure
record
Yes
No
No
Record
linkage
Yes
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Complete
follow up
9
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Complete
follow up
9
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Complete
follow up
9
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Complete
follow up
9
(good)
No
Record
linkage
Yes
Follow up rate
<75% and no
description of
those lost
6
(fair)
Subjects lost
unlikely to
introduce bias
Follow up rate
<75% and no
description of
those lost
9
(good)
6
(fair)
KQ4/5 - PCS
Malcolm, 2006
Somewhat
representative
Same
community as
exposed cohort
Secure
record
Yes
C-10
No
Ascertainment of
exposure
Outcome of
interest not
present at start of
study
known
factors*
additional
factor
Assessment of
outcome
Follow up long
enough for
outcomes to occur
Adequacy of
cohort follow up
Total stars
†
(quality rating)
Selection
of non-exposed
cohort
Representativeness of exposed
cohort
Author, Year
Comparability of
cohorts (Study
controls)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Subjects lost
unlikely to
introduce bias
9
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Complete
follow up
8
(good)
Secure
record
Yes
No
No
Record
linkage
Yes
Complete
follow up
7
(good)
Secure
record
Yes
Yes
Yes
Record
linkage
Yes
Complete
follow up
9
(good)
KQ4/5 – RCS
Adams, 1998
Truly
representative
Bonomo, 1997
Selected
group of users
Fassett, 2007
Somewhat
representative
Langer, 2005
Truly
representative
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
Same
community as
exposed cohort
* Controls for known factors: age, race, BMI, history of GDM, family history of DM
† Quality rating based on EPC Methods Guide (good, fair, poor): total scores of 7-9 were considered good, 4-6 fair, and 0-3 poor.
BMI = body mass index; GDM = gestational diabetes mellitus; DM = diabetes mellitus; PCS = prospective cohort study; RCS = retrospective cohort study
C-11
Appendix D. Evidence Tables
Table D1. Characteristics of studies examining properties of current screening and diagnostic tests for
GDM, Key Question 1
Table D2. Characteristics of studies comparing outcomes for women who were and were not screened for
GDM, Key Question 2
Table D3. Characteristics of studies examining outcomes of mothers and offspring in the absence of
treatment, Key Question 3
Table D4. Characteristics of studies examining treatment outcomes of mothers and offspring, Key
Questions 4 and 5
D-1
Table D1. Characteristics of studies examining properties of current screening and diagnostic tests for GDM, Key Question 1
Author, year
Dates of
study
Country
Agarwal, 2000
June 1998 to
Apr 2000
United Arab
Emirates
Agarwal, 2001
Dec 1997 to
May 1998
Women Analyzed,
n
Screening Practice^
Inclusion/Exclusion
Criteria
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
1644 (+hx = 1276,
+GCT 398)
29.8±5.87 (+hx)
30.2±5.62 (+GCT)
NR
430 (HbA1c)
426 (cFruc)
Exclusion: prescreened by other
methods
Inclusion: attending
antenatal clinic;
referred for OGTT
NR
Selective, 2-step
CC, 513/1644 (31.2%)
+hx, 396/1276 (31.0%)
+GCT, 117/368
(31.8%)
NR
Time of GDM
Confirmation
FPG, various
thresholds
(taken same
time as OGTT)
28.1 wks (+hx)
28.7 wks
(+GCT)
CC, 1991
100g, 3 h
1-2 wks after
OGCT
Risk factor: anytime
during pregnancy
OGCT: 24-28 wks
Selective, 2-step
Risk factor
OGCT
HbA1c ≥5.0%
cFruc ≥210
µmol/L
ADA,
1997/CC,
1991
100g, 3 h
ADA, 116/430 (27.0%)
1-2 wks after
OGCT/ 2428 wks risk
factor
screen
D-2
Study Purpose
Load, Interval
Time of Screening
Inclusion: attending
antenatal clinic;
referred for OGTT
because of clinical
history or +OGCT
Reference†*,
Date
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Exclusion: NR
United Arab
Emirates
Index†,
(Comment)
Purpose: Investigate the
value of FPG as an
alternative screen to
OGCT
Recommendations: In a
high-risk population FPG
offers a simple and
practical screening test
Purpose: Investigate
practical alternative
screening amongst highrisk population which can
be easily performed on a
single blood sample
Recommendations:
Screening high-risk
pregnancies with a
combination of cFRUC
and HbA1c could avoid
OGTT in 37.9% women.
Author, year
Dates of
study
Country
Agarwal,
2005(a)
May 2003 to
Jul 2003
Women Analyzed,
n
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
442
G1: 26.2 ± 5.3
G2: 28.5 ± 5.9
NR
United Arab
Emirates
Agarwal,
2005(b)
Jun 2003 to
Jan 2004
United Arab
Emirates
Screening Practice^
Inclusion/Exclusion
Criteria
1,685
26.6 ± 5.7 (nonGDM)
29.3 ± 6.4 (GDM)
27.7 ± 8.5 (nonGDM)
28.9 ± 5.6 (GDM)
Index†,
(Comment)
Universal, 1-step
ADA, 85 (19%)
WHO, 49 (11%)
Load, Interval
Time of GDM
Confirmation
HbA1c (cutoff
value ≥7.5%;
collected at time
of OGTT)
No screen
ADA, 2004
WHO, 1999
Purpose: Is HbA1c is an
effective screen for GDM
75 g, 2 h
Recommendations:
HbA1c is a poor test to
screen for GDM
24-28wks
Universal, 1-step
Study Purpose
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Time of Screening
Inclusion: Attended
routine antenatal
clinics, 24-28 wks
gestation, complete
OGTT record
Exclusion: Delivery in
other hospital, failure
to undergo OGTT,
hepatic, renal or
evident DM, diet
treatment, previous
GDM, any endocrine
disorder
Inclusion: Attended
routine antenatal
clinics at hospital, 2428 wks gestation,
complete OGTT
record
Reference†*,
Date
FPG, <4.7 and
>5.6 mmol/L
WHO, 1999
WHO, 333 (19.8%)
75 g, 2 h
No screen
24 to 28 wks
Purpose: evaluate the
value of FPG in
screening a high-risk
population for GDM
Recommendations: FPG
has the potential to avoid
nearly 1/3 of OGTTs at
the expense of missing
1/5 of pregnant women
with milder GDM
Exclusion: Delivery in
other hospital, failure
to undergo OGTT,
hepatic, renal or
evident DM, diet
treatment, previous
GDM, any endocrine
D-3
Author, year
Dates of
study
Women Analyzed,
n
Country
Maternal Age,
mean ± SD/median
± IQR (yr)
Agarwal, 2006
BMI, mean ± SD
2
(kg/m )
4,602
May 2004 to
Sep 2005
28.4 ± 6
Screening Practice^
Inclusion/Exclusion
Criteria
Inclusion: Routine
antenatal clinic
attendance at study
hospital
Exclusion: NR
Universal, 2-step
Reference†*,
Date
Load, Interval
Time of GDM
Confirmation
FPG (various
cutoff values)
ADA, 675 (14.7%)
WHO, 979 (21.3%)
ADIPS, 1158 (25.2%)
EASD, 556 (12.1%)
ADA, 2004
WHO, 1999
ADIPS,
1999
EASD, 1998
75 g, 2 h
24-28 wks
24-28 wks
Universal, 1-step
28.8 ± 5.9
Inclusion: Routine
antenatal clinic
attendance
NR
Exclusion: NR
No screen
Agarwal, 2011
849
Inclusion: Routine
antenatal care
Oct 2008 to
May 2009
29.4 ± 6.0
Agarwal, 2008
1,662
Nov 2006 to
Jun 2007
ADA, 186 (11.2%)
FBG (hand-held
glucometer;
cutoff value
≥4.9 mmol/L)
ADA, 2004
75 g, 2 h
24-28 wks
United Arab
Emirates
NR
United Arab
Emirates
Exclusion: Twin
pregnancy,
pregestational DM,
Hx of GDM
Universal, 1-step
ADA, 113 (13.3%)
IADPSG, 279 (32.9%)
WHO, 156 (20.3%)
ADIPS, 172 (20.3%
EASD, 90 (10.6%)
24-28 wks
Serum
fructosamine
(cutoff value
≥237 µmol/L)
ADA, 2004
IADPSG,
2010
WHO, 1999
ADIPS,
1999
EASD, 1998
75 g, 2 h
24-28 wks
D-4
Study Purpose
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Time of Screening
NR
United Arab
Emirates
Index†,
(Comment)
Purpose: Effect of
diagnostic criteria on the
usefulness of FPG as a
screen for GDM
Recommendations: Initial
testing by FPG can
decrease the number of
OGTTs needed to
diagnose GDM
Purpose: Test the practical
value of measuring FBG
vs. FPG
Recommendations: FBG
is a simple, practical,
cost-effective and patientfriendly approach to
screen for GDM
Purpose: Evaluate the
value of serum
fructosamine to screen
for GDM
Recommendations:
Serum fructosamine is a
poor test to screen for
GDM
Author, year
Dates of
study
Country
Ardawi,
2000
Women Analyzed,
n
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
818
Jun 1996 to
Jun 1998
G1:29.2 ± 4.6
G2:30.7 ± 4.8
G3:32.1 ± 5.1
Saudi Arabia
NR
Ayach,
2006
341
Jul 1997 to
Dec 1999
Brazil
Screening Practice^
Inclusion/Exclusion
Criteria
Age ≥25, n = 54
(15.8%)
BMI ≥27, n = 49
(14.4%)
Index†,
(Comment)
Universal, 2-step
Load, Interval
Time of GDM
Confirmation
50 g OGCT
(≥7.2 mmol/L)
NDDG, 102 (12.5%)
NDDG, 1979
100 g, 3 h
Exclusion: NR
Inclusion: All pregnant
women, no Hx of DM,
sought care in study
st
hospital during 1
half of pregnancy
24-28 wks
Universal, 2-step
ADA, 13 (3.8%)
24-28 wks
Exclusion: Failure to
perform or finish
screening/diagnostic
test, withdrawal of
consent or premature
termination of
pregnancy,
miscarriage,
pseudocyesis,
premature birth, fetal
death, intolerance to
oral glucose test
D-5
Study Purpose
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Time of Screening
Inclusion: Attended
antenatal care clinics
at 2 hospitals
Reference†*,
Date
FPG and risk
factors (age ≥
25, BMI before
pregnancy ≥ 27
2
kg/m , family or
personal
history of
diabetes, and
membership of
an ethnic group
with high
prevalence of
GDM)
ADA, 2002
Purpose: Evaluate
applicability of the 50 g
OGCT as a screening
test for GDM in relation to
pregnancy outcomes
Recommendations: 50 g
OGT at 24-28 weeks with
a cutoff value of 7.8
mmol/L is a reliable
screening test for GDM
Purpose: Compare FPG +
risk factors vs.50 g GTT
100 g, 3 h
24-28 wks
Recommendations: FPG
+ risk factors are more
appropriate for screening
compared with 50 g
OGCT
Author, year
Dates of
study
Country
Balaji,
2011
Women Analyzed,
n
Screening Practice^
Inclusion/Exclusion
Criteria
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
1,463
23.6 ± 3.3
NR
21.5 ± 4.1
Index†,
(Comment)
Universal, 1-step
Study Purpose
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Load, Interval
Time of GDM
Confirmation
Time of Screening
Inclusion: Visiting
antenatal clinic for
the first time in
second or third
trimester
Reference†*,
Date
FPG (IADPSG
≥5.1 mmol/L)
WHO, 196 (13.4%)
WHO, 1999
75 g, 2 h
24-28 wks
No screen
24-28 wks
Purpose: Ascertain the
ability of FPG to diagnose
glucose intolerance
during pregnancy in
Asian Indians
India
Exclusion: Hx of
GDM or DM
Balaji,
2012
819
23.8 ± 3.48
NR
21.2 ± 4.87
Inclusion: Pregnant
women at 24-28
wks, attending
community health
center
Universal, 1-step
WHO, 86 (10.5%)
No screen
India
Exclusion: NR
Berkus, 1995
80
NR
G1: 28.1 ± 5
G2: 25.7 ± 5
U.S.
Inclusion: Nonhypertensive women,
recruited from
obstetric clinic in
Texas, non diabetic
CBG (point-ofcare testing
with
glucometer; 75
g glucose load,
2 h sample,
cutoff value of
≥7.8 mmol/L)
WHO, 1999
75 g, 2 h
24-28 wks
NR, 2-step
50 g OGTT
NDDG, 1979
NDDG, 21/40 (26%)
WHO, 20/40 (50%)
75 g OGTT,
WHO
100g, 3 h
G1:28.6 ±4
G2:30.6 ±4
NR
Recommendations: FPG
is not suitable for
diagnosis of GDM in this
population
Purpose: Compare pointof-care measured CBG
with a glucometer and
lab-estimated VPG
Recommendations: CBG
value at a 2 h plasma
glucose ≥7.8 mmol/L may
be recommended for the
diagnosis of GDM
Purpose: Determine
whether glucose
abnormality, as shown by
GTT periodicity, is not
affected by different
glucose loads
Exclusion: NR
Recommendations: GTT
periodicity identifies
patients with GDM
regardless of GTT load
D-6
Author, year
Dates of
study
Country
Bobrowski,
1996
Women Analyzed,
n
Screening Practice^
Inclusion/Exclusion
Criteria
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
422
Index†,
(Comment)
NR (included women
with abnormal OGCT)
Load, Interval
Time of GDM
Confirmation
50 g OGTT,
≥135 mg/dL
NDDG, 1979
CC,1982
NR
Exclusion: no followup OGTT
Jul 1992 to
Jan 1994
Brustman,
1995
24-28 wks
100 g, 3 h
NDDG, 124(29%)
CC, 161 (38%)
U.S.
32
28 ± 5
NR
NR
U.S.
Inclusion: Women 2626 wks gestation,
abnormal glucose
screen ≥130 mg/dl
after 24 wks
gestation
NR (included women
with abnormal OGCT)
1-2 wks after
GCT
rd
IWC, 3 (75 g,
3-h OGTT)
NDDG, 1979
100 g, 3 h
NDDG, 16 (50%)
IWC, 6 (19%)
26-36 wks
Exclusion: NR
Buhling,
2004
912
28.5 ± 5
Jun 1997 to
Jan 2000
Inclusion: Received
prenatal care at
clinic, no previous
GDM testing
Universal, 2-step
ADA, 37 (4.1%)
Study Purpose
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Time of Screening
Inclusion: + OGCT
screen
Reference†*,
Date
50g OGCT
(≥140 mg/dL)
ADA, 2001
75 g, 2 h
Purpose: examine the
utility of various 50 g
screen cutoff values in
establishing the diagnosis
of gestational diabetes
Recommendations: 50-g
glucose screen result
≥220 mg/dL can obviate
the need for a 3-h OGTT
Purpose: Compare results
of a 75 g, 3h OGTT with
a 100g OGTT
Recommendations: 75 g
OGTT using the NDDG
criteria, recognizes
carbohydrate intolerance
in pregnancy
Purpose: Evaluate the
sensitivity of the glucosesticks for screening for
GDM
33.8 ±3 wks
23.6 ± 4.4
Recommendations: Urine
glucose dip stick analysis
is not useful to detect
GDM
Exclusion: NR
Germany
D-7
Author, year
Dates of
study
Country
Cetin,
1996
Oct 1994 to
Jan 1996
Turkey
Chastang,
2003
Women Analyzed,
n
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
274
G1:27 (19-37)
G2: 28 (18-37)
G3: 29 (19-41)
G1: 24.8 (17.340.1)
G2: 24.5 (17-40)
G3: 25 (19.3-39.8)
354
31.4 ± 4.6
Jun 1997 to
Jun 1998
France
Screening Practice^
Inclusion/Exclusion
Criteria
22.5 ± 4.1
Index†,
(Comment)
Exclusion: Hx of
preexisting diabetes,
preeclampsia, regular
ingestion of any drug,
delivery ≤28 wks ,
premature rupture of
membranes
Inclusion: Presented
at least 1 RF for
GDM: >35 years, BMI
> 25, family Hx of
diabetes, personal
Hx of GDM, Hx of
macrosomia/ LGA,
Hx or preeclampsia,
presence of
obstetrical event(s) in
current pregnancy,
excessive weight
gain during in current
pregnancy
Universal, 2-step
Load, Interval
Time of GDM
Confirmation
50g, 1 h OGCT
(≥140 mg/dL)
NDDG, 17 (6.2%)
NDDG, NR
100 g, 3 h
26-28 wks
CC, 69 (20%)
≥25 g
carbohydrate
breakfast
24 to 28 wks
FPG
Selective, 2-step
D-8
Purpose: Examine different
cutoff values with regard
to the time of patient’s
last meal
Recommendations:
Different cutoff values
lead to improved
efficiency of the OGCT
and decreased frequency
of OGTT
CNGOF,
1998
(based on
CC criteria)
Purpose: Validate a
diagnostic test for GDM
which predicts the risk of
macrosomia
100 g, 3 h
Recommendations:
Standard 50 g
carbohydrate breakfast
is more sensitive than the
50 g GCT to screen
women at risk of
macrosomia
24-28 wks
Exclusion: NR
Study Purpose
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Time of Screening
Inclusion: Women >
24 yrs, 24-28 wks
gestation, examined
by obstetrician before
20 wks, singleton
pregnancy
Reference†*,
Date
Author, year
Dates of
study
Country
Chevalier,
2011
Jan 2002 to
Dec 2006
France
De Los
Monteros,
1999
Jul 1996 to
Dec 1996
Women Analyzed,
n
Screening Practice^
Inclusion/Exclusion
Criteria
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
11,545
32.8 ± 5.5 (GDM)
30.7 ± 5.3 (no
GDM)
28.6 ± 5.7 (GDM)
27.8 ± 4.9 (no
GDM)
445
>25 (n=359)
<25 (n=86)
Inclusion: screened
between 24-28 at
hospital
Exclusion: NR
Inclusion: 24-28 wks
gestation, attending
medical centre for
routine care
26.9 ± 5.6
NR
22.4 ± 3.8
Exclusion: NR
709
CC (≥130 mg/dL), 344
(4.3%)
CC (≥140 mg/dL), 300
(3.9%)
Universal, 2-step
Time of GDM
Confirmation
OGCT, ≥130
mg/dL and ≥140
mg/dL
Postprandial 50
g OGCT
NDDG, 43 (9.7%)
CC, 52 (11.7%)
Sacks, 62 (13.9%)
CNGOF,
1996
(based on
CC, 1982)
Purpose: Explore GDM
screening according to
the 1996 French
guidelines
100 g, 3 h
Recommendations: Twostep screening strategy
for GDM was neither
relevant nor efficient
Purpose: Study sensitivity
and specificity of the 50
g, 1 h GCT performed 1
to 2 h after a nonstandardized home
breakfast
NDDG, 1979
CC, 1982
Sacks, 1989
100 g, 3 h
24-28 wks
1 wk after
OGCT
Universal, 2-step
50 g OGCT
NDDG, 1979
NDDG, 10 (1.4%)
WHO, 111 (15.7%)
WHO, 1980
(75 g, 2 h
OGTT)
100 g, 3 h
24-28 wks
Thailand
D-9
Study Purpose
Load, Interval
24-28 wks
Deerochanawong,
1996
Mexico
Universal, 2-step
Reference†*,
Date
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Time of Screening
Exclusion: Previous
Hx of DM, consent
withdrawal during
either glucose
tolerance test,
inability to recall last
menstrual period, Hx
of regular drug
ingestion during
pregnancy
Inclusion: Attending
antenatal clinic, no
prepregnancy DM
NR
Index†,
(Comment)
Within 7
days
Recommendations:
Sensitivity after breakfast
was similar, based on the
NDDG and CC criteria for
GDM
Purpose: Compare criteria
of the NDDG and WHO
for pregnancy outcomes
Recommendations: WHO
criteria resulted in poorer
pregnancy outcomes but
fewer perinatal
complications were
missed than with the
NDDG criteria
Author, year
Dates of
study
Country
Eslamian,
2008
Women Analyzed,
n
Screening Practice^
Inclusion/Exclusion
Criteria
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
138
27.5 ± 4.6
Universal, 2-step
Exclusion: Pregestational DM,
current GDM
24-28 wks
Inclusion: Prenatal
clinic attendance at
study center, referred
for 50 g GCT
between 24-28 wks
Universal, 2-step
CC, 12 (8.6%)
24.9 ± 3.1
Gandevani,
2011
1,804
32.5 ± NR
2007 to 2008
23.3 ± 2.4
CC, 130 (7.2%)
Time of GDM
Confirmation
Standard
breakfast
containing 50 g
simple sugar
50 g OGCT
(various cutoff
values)
CC, NR
100 g, 3 h
CC, 1982
100 g, 3 h
Hill,
2005
830
24 (16-40)
Jun 1997 to
Aug 1998
India
23.1 (20.7-25.7)
Selective, 2-step
CC, 49 (6%)
NR
Exclusion:
Prepregnancy DM
D-10
Risk Factors
(one or more of
the following:
2
BMI ≥25 kg/m ;
family Hx of DM
in a first or
second degree
relative; poor
obstetric Hx;
previous baby
weighing ≥3800
g; PIH;
polyhydramnios
Purpose: Compare a
standard breakfast with a
50 g glucola-based
OGCT
Recommendations:
Standard breakfast can
be used as an alternative
method for assessing
carbohydrate intolerance
Purpose: Investigate cutoff
value of GCT in an
Iranian population
24-28 wks
Recommendations: Best
cutoff value is 135 mg/dL
to identify GDM
CC, 1982
Purpose: Determine the
incidence of GDM in one
urban maternity unit in
South India and examine
its effect on the offspring
Iran
Exclusion: Glucose
intolerance before
pregnancy, Hx of
GDM
Inclusion: Planned to
deliver at hospital,
singleton pregnancy,
<32 wks GA
determined by LMP
or a first trimester
ultrasound scan
Study Purpose
Load, Interval
Time of Screening
Inclusion: Patients
receiving prenatal
care
Reference†*,
Date
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
NR
Iran
Index†,
(Comment)
100 g, 3 h
28-32 wks
Recommendations: Effect
of maternal glucose
concentrations on
neonatal anthropometry
is continuous and
extends into those
diagnosed as normal
Author, year
Dates of
study
Country
Jakobi,
2003
Women Analyzed,
n
Screening Practice^
Inclusion/Exclusion
Criteria
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
180
NR
1998 to 1999
NR
Index†,
(Comment)
Abnormal OGCT
Load, Interval
Time of GDM
Confirmation
BG/ portable
glucose meter
rd
IWC, 25 (13.9%)
IWC, 3
(similar to
NDDG)
NR
100 g, 3 h
Israel
Exclusion: NR
Jensen, 2003
5,235
1999 to 2000
NR
Denmark
NR
Inclusion: Risk group:
women presenting ≥1
RF. Non-risk group:
contacted by study
midwife at first
appointment
Study Purpose
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Time of Screening
Inclusion: Positive 50
g OGCT (≥7.8
mmol/L), referred to
high-risk pregnancy
clinic
Reference†*,
Date
Purpose: Evaluate
perinatal effects of
replacing current
methods for 100 g OGTT
with portable glucose
meters
28-32 wks
Universal, 2-step
WHO, 124 (2%)
NR
Exclusion: Preexisting
DM, <18 yrs, delivery
or migration before
30 wks, first booking
later than 30 wks
D-11
Risk factors
(glucosuria,
GDM in a
previous
pregnancy,
prepregnancy
2
BMI ≥27 kg/m ,
family history of
DM, and
previous
delivery of
macrosomic
infant)
WHO, 1998
75 g, 2 h
Recommendations: No
difference between the 2
methods
Purpose: Evaluate a
screening model for GDM
using clinical risk
indicators
28-32 wks
Recommendations: Using
risk factor assessment
reduces the need for
screening and diagnostic
testing in 66% pregnant
women
Author, year
Dates of
study
Country
Kashi,
2007
Women Analyzed,
n
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
200
27.8 ± 95.2
NR
29.6 ± 4.5
Iran
Kauffman,
2006
123
NR
NR
NR
U.S.
Screening Practice^
Inclusion/Exclusion
Criteria
Index†,
(Comment)
Exclusion:
Pregestational overt
DM
Inclusion: Women
attending obstetrical
clinic, 24-28 wks
gestation with
consent to undergo
100 g, 3h OGTT in
lieu of 50 g screen
Selective, 2-step
Load, Interval
Time of GDM
Confirmation
FPG (≥91.5
mg/dL)
ADA, 20 (10%)
NDDG, 16 (13.0%)
CC, 25 (20.3%)
homeostatic
insulin
sensitivity
indices (HOMA1, HOMA-2,
QUICKI)
FPG ≥92 mg/dL
FPI ≥93 µmol/L
Exclusion: Hx DM or
GDM, untreated
endocrine disorders,
medications with
impact on circulating
glucose or insulin
levels
D-12
ADA, 2006
100 g, 3 h
24-28 wks
No screen, OGTT in lieu
of OGCT
Study Purpose
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Time of Screening
Inclusion: Referred to
prenatal clinic, ≥1 risk
factors: >25 years
old, Hx of recurrent
abortion, previous
GDM, preeclampsia,
macrosomia, still
birth, DM in first
degree family or
pregestational BMI
2
>25 kg/m
Reference†*,
Date
Purpose: Determine a
cutoff point of FPG for
screening for GDM
1-2 wks after
+OGCT
Recommendations: FPG
level of 91.5 mmol/dL
showed highest
sensitivity and specificity
NDDG, 1979
CC, 1982
Purpose: investigate
homeostatic indices of
insulin sensitivity to
screen for GDM
100 g, 3 h
24-28 wks
Recommendations: FPG
and the homeostatic
insulin sensitivity indices
are sensitive alternatives
to OGCT
Author, year
Dates of
study
Country
Lamar,
1999
Women Analyzed,
n
Screening Practice^
Inclusion/Exclusion
Criteria
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
136
26 ± 5.3
NR
NR
U.S.
NDDG, 5 (3.7%)
Index†,
(Comment)
NR, 2-step
NDDG, 5 (3.7%)
24-28 wks
Load, Interval
Time of GDM
Confirmation
50 g OGCT
(traditional and
alternative
sugar source 28 jelly beans
consisting of 50
g of simple
sugar)
Exclusion: NR
Maegawa,
2003
Apr 1999 to
Sep 2001
Japan
749
28.9±4.1 (normal)
30.7±2.5 (early)
34.1±3.3 (late)
Inclusion: Women in
st
1 trimester;
attending hospital
JSOG, 22 (2.9%)
Exclusion: Hx of DM
21.0±2.9 (normal)
24.8±6.2 (early)
22.6±2.3 (late)
Mello,
2006
227 (16-20 wks)
976 (26-30 wks)
Jan 1997 to
Dec 1999
Italy
NR
Inclusion: nonobese;
nondiabetic;
singleton pregnancy
Universal, 1-step
Early: CC 41/227 (18.1%)
ADA 15/227 (6.75)
Exclusion: NR
NR
ACOG, 1994
(Values
same as
NDDG)
Late: CC 60/484 (12.4%)
ADA, 26/484 (4.4%)
D-13
GCT*, 130
mg/dL and140
mg/dL
FPG* 85 mg/dL
HbA1c *4,8%
and 5.8%
*Taken in both
st
nd
1 and 2
trimester
75 g, 2 h (ADA)
OGTT
JSOG, 2002
(Values
same as
ADA, 75 g)
75 g, 2 h
2-4 wks after
nd
2 trimester
screen
CC, 1982
100 g, 3 h
16-20 wks
26-30 wks
Purpose: Determine if a
standardized dose of jelly
beans is an alternative
sugar source to the 50 g
glucose beverage to
screen for GDM
100 g, 3 h
Within 7-10
days of
OGCT
Universal, 2-step
Study Purpose
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Time of Screening
Inclusion: Women in
general obstetric
population at
institution ≥18 yrs
and between 24-28
wks, no Hx of overt
DM
Reference†*,
Date
1 wk after 75
g
Recommendations: Jelly
beans provide a “dose” of
simple carbohydrate
similar to that of the 50 g
glucose beverage but
with suboptimal
sensitivity
Purpose Characteristics of
various screening
procedures for GDM in
Japan during the first
trimester and between 24
and 28 wks of pregnancy
Recommendations: Of 22
with GDM, 14 were
diagnosed in the first
trimester and 8 in the
second trimester.
Purpose: Investigate the
comparability of the 75 g
and the 100 g tests in the
diagnosis of GDM
Recommendations: There
was only weak diagnostic
agreement between 75-g
and 100-g glucose loads
Author, year
Dates of
study
Country
Moses,
2011
Jan 2010 to
Jun 2010
Women Analyzed,
n
Screening Practice^
Inclusion/Exclusion
Criteria
Maternal Age,
mean ± SD/median
± IQR (yr)
Index†,
(Comment)
Load, Interval
Time of GDM
Confirmation
Time of Screening
Inclusion: NR
Univresal, 1-step
NR
Exclusion: NR
ADIPS, 123 (9.6%)
IADPSG, 166 (13.0%)
IADPSG, 2010
ADIPS,
1991
75 g, 2 h
Purpose: Compare the
prevalence of GDM using
IADPSG criteria vs. ADIP
criteria
NR
NR
Australia
Ostlund, 2003
4,918
Jul 1994 to
Jun 1996
NR
Inclusion: Nondiabetic
women visiting
maternal health care
clinics in Sweden
NR
Sweden
Study Purpose
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
BMI, mean ± SD
2
(kg/m )
1 ,275
Reference†*,
Date
Universal, 2-step
WHO, 61 (1.7%)
NR
Exclusion: Prepregnancy DM
D-14
Anamnestic risk
factors
(Heredity, nonNordic origin,
prior
macrosomia,
prior GDM,
multipara, prior
macrosomia,
and prior GDM)
WHO, 1980
75 g, 2 h
28-32 wks
Recommendations:
IADPSG criteria
Increased the prevalence
of GDM from 9.6% to
13.0%
Purpose: Determine
prevalence of GDM and
the value of traditional
anamnestic risk factors
for predicting the
outcome of the OGTT
Recommendations:
Traditional risk factors as
an indicator to perform an
OGTT gives a low
sensitivity to detect GDM
Author, year
Dates of
study
Country
PereaCarrasco,
2002
NR
Women Analyzed,
n
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
578
NR
NR
Index†,
(Comment)
Universal, 2-step
IWC, 46 (7%)
24-28 wks
520
28.4 ± 0.2
1995 to 1997
Inclusion: Singleton
pregnancy, attended
hospital, delivery >28
wks
Time of GDM
Confirmation
rd
Index test (I) =
(fructosamine/
total protein) (glucose/100)
IWC, 3
(same as
NDDG
thresholds)
I = ≥27.2
100 g, 3 h
24-28 wks
Universal, 2-step
IWC, 53 (10.2%)
FPG (≥4.8
mmol/L, 86
mg/dL)
th
IWC, 4
(similar to
CC/ADA
2000/10)
23.8 ± 0.2
Switzerland
PoyhonenAlho,
2004
532
Jan 1996 to
Aug 1998
NR
NR
Exclusion: Preexisting DM, not
examined before 24
wks
Inclusion: Caucasian,
attendance at
primary health care
units
Study Purpose
Load, Interval
Time of Screening
Inclusion: Attended
routine antenatal
clinic, OGCT and
OGTT between 2428 wks
Reference†*,
Date
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Exclusion: Multiple
pregnancies
Spain
Perucchini,
1999
Screening Practice^
Inclusion/Exclusion
Criteria
100 g, 3 h
Purpose: Devise an index
test to improve screening
sensitivity and specificity,
offering better screening
capability and greater
ease of diagnosis
Recommendations:
Proposed index offers an
efficient screening test for
GDM, and with more
stringent cutoff points
may be applicable as a
single-step diagnostic
procedure
Purpose: Evaluate FPG vs.
the 1 h 50 g OGCT
Recommendations: More
women are referred for
the OTT using FPG vs.
those using the OGCT
24-28wks
Universal, 2-step
Author defined, 123
(23%)
Exclusion: Prepregnancy DM
Finland
D-15
Risk factor
based
screening (BMI
>27; age >40;
previous child
>4500 g;
previous GDM;
glucosuria; or
macrosomia in
current
pregnancy)
Author
defined
75 g, 2 h
Fasting
≥4.8, 1h
≥10.0, 2h
≥8.7 mmol/L
26-28 wks
Purpose: Compare
whether universal
screening by OGCT will
identify more women with
GDM vs. risk factor
based screening
Recommendations: 50 g
OGCT identified a higher
number women with
GDM
Author, year
Dates of
study
Country
Rajput,
2011
NR
Women Analyzed,
n
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
607
16–20 18%; 21–25
58%; 26–30 20%;
>30 4%
India
<18.5 38%; 18.5–
24.9 54%; ≥25 8%
Reichelt,
1998
4,977
27.9 ± 5.5
May 1991 to
Aug 1995
Brazil
Rey,
2004
Inclusion: all pregnant
women 24-28 wks
GA;
Inclusion: Women ≥20
yrs, 21-28 wks
gestation
188
Inclusion: all women
between 24 and 28
wks; normal firsttrimester glucose
testing; screened
according to CDA
screening program
NR
Universal, 1-step
ADA, 43 (7.1%)
IADPSG, 144 (23.7%)
Reference†*,
Date
Study Purpose
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Load, Interval
Time of GDM
Confirmation
HbA1c , >5.45%
and >5.25%
(diagnostic)
Exclusion: know Dx
DM, anemia, chronic
renal, pancreatic or
other severe illness
Exclusion: Prepregnancy DM
9 mo period
Index†,
(Comment)
Time of Screening
26.1 ± 4.1
30.2 ± 5.2
Canada
Screening Practice^
Inclusion/Exclusion
Criteria
ADA, 2010
IADPSG,
2010
Purpose: Evaluate the
utility of HbA1c in
combination with OGTT
for diagnosis of GDM
75 g, 2 h
24-28 wks
Universal, 1-step
FPG (≥87
mg/dL)
WHO, 379 (7.6%)
WHO, 1994
75 g, 2 h
24-28 wks
st
Normal 1 trimester
screen
CDA, 21 (11.2%)
25.7 ± 1.2 wks
Exclusion: NR
D-16
Recommendations:
HbA1c in combination
with OGTT can obviate
the need of OGTT in
almost two-thirds of
women with GDM
Purpose: Evaluate FPG as
a screening test for GDM
GCT, 7.8
mmol/L
FPG, 4.5
mmol/L
FCG, 4.6
mmol/L
Recommendations: FPG
is a useful screening test
for GDM
CDA, 1998
75 g, 2 h
27.2 ± 1.4
wks
Purpose: compare the
performance in screening
of the 1 h, 50 g GCT,
FPG and FCG
Recommendations: There
is not enough benefit to
be gained by using the
FPG instead of the GCT
as the screening test for
GDM
Author, year
Dates of
study
Country
Rust,
1998
Women Analyzed,
n
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
448
23.7 ± 6.1
Jul 1994 to
Jun 1995
Screening Practice^
Inclusion/Exclusion
Criteria
Index†,
(Comment)
26.8 ± 7.6
Universal, 2-step
ADA, 16 (3.6%)
≥20 wks
Study Purpose
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Load, Interval
Time of GDM
Confirmation
Time of Screening
Inclusion: Women at
medical centre
obstetric clinics, >20
wks gestation
Reference†*,
Date
Postprandial 50
g GCT
(1 and 2 hrs
post meal
glucose load)
ADA,
100 g, 3 h
20 wks
Purpose: Compare 2 h
postprandial glucose
measurements with the 1
h, 50 g glucola screen as
a predictor of GDM
Exclusion: NR
U.S.
Sacks,
2003
4,507
NR
Feb 1998 to
Jul 1999
NR
Inclusion: Prenatal
visit at medical
center, no known
diabetic Hx, able to
return for lab work
and glucose testing
Universal, 2-step
FPG (≥83
mg/dL)
ADA, 2001
ADA, 302 (6.7%)
75 g, 2 h
≥23 wk
NR
Recommendations: 1 h
glucola test is a reliable
screening test for GDM
whereas the 2 h
postprandial test is not
Purpose: Determine
whether the FPG test
administered at the first
prenatal visit is an
efficient screen for GDM
Recommendations: FPG
has poor specificity (high
false-positive rate)
making it an inefficient
screening test
U.S.
Exclusion: Transferred
care to other
institution, began
prenatal care or
screened elsewhere,
spontaneous abortion
after enrollment
D-17
Author, year
Dates of
study
Country
Siribaddana,
2003
Women Analyzed,
n
Screening Practice^
Inclusion/Exclusion
Criteria
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
721
Time of GDM
Confirmation
Universal, 2-step
50g OGCT
WHO, 1985
NR
Inclusion: Attended
antenatal clinic
hospital
WHO, 40 (5.5%)
75 g, 2 h
NR
Exclusion: Known DM
24-28 wks
Traditional risk
factors (Age,
family Hx,
parity, Hx of
poor pregnancy
outcomes)
1,502
Inclusion: Attended
prenatal clinics
27.3 ± 6.1
2007 to 2010
25.7 ± 6.9
Exclusion: Hx
hyperglycemia, on
medication known to
affect glucose
metabolism
Universal, 2-step
Time intervals
of 100 g OGTT
1 wk after
OGCT
ADA, 2009
ADA, 216 (13.1%)
100 g, 3 h
24-28 wks
1-2 wks after
+OGCT
D-18
Study Purpose
Load, Interval
Time of Screening
Sri Lanka
Iran
Reference†*,
Date
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
NR
Soheilykhah,
2010
Index†,
(Comment)
Purpose: Determine the
prevalence of GDM in a
Sri Lankan population
using WHO criteria, and
establish the predictive
value of a 50g OGCT vs.
the OGTT
Recommendations:
Traditional risk factors did
not predict GDM;
screening for GDM
should be performed in
all women with a GCT
Purpose: To find an
appropriate and simple
way to perform screening
tests for GDM
Recommendations: A
positive GCT result (≥130
mg/dL) with subsequent 2
h 100g OGTT (≥150
mg/dL) will diagnose
GDM
Author, year
Dates of
study
Country
Soonthornpun,
2003
Women Analyzed,
n
Screening Practice^
Inclusion/Exclusion
Criteria
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
42
33.6 ± 5.4
NR
Inclusion: 50 g OGCT
values ≥140 mg/dL
at screening between
14-36 wks
Study Purpose
Load, Interval
Time of GDM
Confirmation
ADA, 2000 (75
g, 2 h GTT)
CC, 1982
100 g, 3 h
CC, 9 (21.4%)
ADA, 3 (7.1%)
28.2 ± 4.2
Purpose: Test the validity
of a 75 g, 2 h OGTT
using the ADA criteria
and reference values for
the 100 g, 3 h OGTT
Exclusion: NR
521
29.6 ± 4.8
Jan 2006 to
Jul 2006
NR (included women
with abnormal OGCT)
Reference†*,
Date
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Time of Screening
NR
Thailand
Tan,
2007
Index†,
(Comment)
Inclusion: antenatal
booking; ≥1 risk
factors
Universal, 2-step
Selective, 2-step
WHO, 180 (34.5%)
26.7 ± 4.6
Exclusion: NR
28.8 ± 6.4 wks
Malaysia
D-19
Clinical risk
factors, 1 or
more: ≥35
years, Hx
macrosomia
≥4 kg; Hx
intrauterine
death; weight
≥70 kg, BMI
≥30, Hx of
GDM, family
Hx DM, or
glycosuria
WHO, 1999
75 g, 1 h
Recommendations: The
prevalence of GDM was
lower using the 75 g
OGTT using the criteria
and reference values of
the 100 g OGTT
Purpose: Evaluate the role
of risk factors in
conjunction with GCT to
determine an appropriate
threshold for 1 h GCT
Recommendations: 2-step
screening threshold for a
positive GCT should be ≥
7.6 mmol/L. After a GCT
result, clinical risk factors
are no longer useful in
selecting women.
Author, year
Dates of
study
Country
Tri-Hospital
(2 papers)
Sermer, 1998
Naylor, 1997
Women Analyzed,
n
Screening Practice^
Inclusion/Exclusion
Criteria
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
3,836
NR
NR
Sept 1989 to
Mar 1992
Index†,
(Comment)
Universal, 2-step
NDDG, 145 (3.8%)
Load, Interval
Time of GDM
Confirmation
50 g, 2 h OGCT
(time of last
meal prior to
glucose load)
26-28 wks
NDDG, 1979
100 g, 3 h
Exclusion: NR
42
NR
27.5 ± 4.3
Turkey
NR
Inclusion: Attending
outpatient clinic,
OGCT between 2428 wks
Universal, 2-step
CC, 1988
CC, 14 (33%)
Serum
fructosamine
(≥2.85 mmol/L)
24-28 wks
HbA1c (≥7.2%)
NR
100 g, 3 h
Exclusion:
Pregnancies beyond
wk 28 previously
diagnosed as DM
van Leeuwen,
2007
1,301
Inclusion: NR
Universal, 2-step
30.8 ± 4.9
Exclusion: Known
preexisting diabetes;
no prenatal care
before 24 wks of
gestation
WHO, 48 (3.7%)
75 g, 2 h
24-28 wks
NR
NR
24.2 ± 4.6
Netherlands
Purpose: Established more
efficient screening
strategies for detection of
GDM
26-28 wks
Canada
Uncu, 1995
Study Purpose
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Time of Screening
Inclusion: >24 yrs at
time of delivery, no
Hx of DM examined
by physician before
24 wks gestation,
delivery >28 wks
Reference†*,
Date
Random 50 g
glucose test
WHO, NR
Recommendations:
Increasing maternal
carbohydrate intolerance
is associated with a
graded increase in
adverse maternal and
fetal outcomes
Purpose: Evaluated the
sensitivity and specificity
of 50 g OGCT, serum
fructosamine and HbA1c
levels as screening tests
for GDM
Recommendations:
HbA1c and fructosamine
levels are reliable
methods to 50 g OGCT
Purpose: Compare the
accuracy measures of the
random glucose test and
the 50 g GCT as
screening tests for GDM
Recommendations: The
50 g glucose challenge
test is more useful than
the random glucose test
D-20
Author, year
Dates of
study
Country
Weerakiet,
2006
Women Analyzed,
n
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
359
31.8 ± 6.1
Jul 2004 to
Mar 2005
23.2 ± 4.3
Thailand
Wijeyaratne,
2006
Screening Practice^
Inclusion/Exclusion
Criteria
853
Inclusion: Singleton
pregnancy,
presenting ≥1 risk
factor for GDM: age
>30, obesity, family
Hx of DM, prior GDM,
glucosuria, signs of
hyperglycemia, Hx of
poor obstetric
outcome
Exclusion:
Hypertension, known
DM, known chronic
disease requiring Tx,
positive result for
syphilis, hepatitis B
(HBSAg), HIV
Inclusion: Registered
for antenatal care
NR
Selective, 2-step
ADA, 66 (16.7%)
Risk factor screen
recommended by
ACOG
Time of GDM
Confirmation
Adiponectin
levels (10
µmg/mL)
ADA, 2000
50g OGCT
(≥140 mg/dL)
24-28 wks
100 g, 3 h
FBG (≥4.1
mmol/L)
Risk factors
proposed by
ADA, NR
Sri Lanka
D-21
WHO, 1999
75 g, 2 h
FPG (≥4.7
mmol/L)
24-28 wks
Purpose: Evaluate
adiponectin as a
predictive factor for GDM
and appropriate as a
screening test for GDM
Recommendations:
Adiponectin was not as
strong a predictor as
GCT
21-27 weeks (OGCT)
Selective, 2-step
Study Purpose
Load, Interval
WHO, 144 (16.3%)
Exclusion: Established
glucose intolerance
Reference†*,
Date
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Time of Screening
NR
Apr 2003 to
Jul 2003
Index†,
(Comment)
Purpose: Evaluate tests
used for screening and
confirmation of GDM in
Sri Lanka
24-28 wks
Recommendations: Urine
and FBG are unsuitable
for screening
Author, year
Dates of
study
Country
Yachi,
2011
Women Analyzed,
n
Maternal Age,
mean ± SD/median
± IQR (yr)
BMI, mean ± SD
2
(kg/m )
509
33.4 ± 3.7
Sep 2008 to
Jan 2010
20 ± 2.5
Japan
Yogev,
2004
1995 to 1999
U.S.
Screening Practice^
Inclusion/Exclusion
Criteria
2,541
26.1±6.3(>130)
29.2±7.0 (>180)
26.4±3.7 (>130)
27.6±3.1 (>180)
Index†,
(Comment)
Load, Interval
Time of GDM
Confirmation
Time of Screening
Universal, 2-step
Exclusion: FPG levels
≥2.5 mmol/L; missing
or incomplete data
24-29 wks
Inclusion: Singleton
pregnancies;
screened at 24-28
wks
Universal, 2-step
Exclusion: No Hx of
GDM and pregestational DM
24-28 wks
JSOG, 8 (2.0%)
CC, 469 (6.8%)
NDDG, NR (7.3%)
Study Purpose
Conclusion(s)
Prevalence of GDM
Criteria, n (%)
Inclusion: Visited
clinic; ≥13wks
gestation
Reference†*,
Date
FPG (≥3.66
mmol/L at 10
wks)
JSOG, 1999
FPI (≥36.69
mmol/L at 10
wks)
26-29 wks
50 g OGCT
(130, 135, 140
mg/dL)
CC, 1982
NDDG, 1979
75 g, 2 h
100 g, 3 h
+OGCT
only, 1-2
wks OGCT
Purpose: Determine early
screening tests and risk
factors predictive of
glucose intolerance in
later pregnancy
Recommendations: FPG
is not an acceptable
screening test for glucose
intolerance
Purpose: Describe the
predictive value for GDM
using different OGCT
thresholds in MexicanAmerican women
Recommendations: A
threshold of ≥130 mg/dL
is recommended
Notes: ^ Screening practice described in study;†Index and reference data used in this review. *Complete diagnostic criteria can be found in Table 1. ADA = American Diabetes
Association; ADIPS = Australian Diabetes in Pregnancy Society; BMI = body mass index; CBG = capillary blood glucose; CHT = chronic hypertension; d = day; dL = deciliter; DM
= diabetes mellitus; Dx = diagnosis/diagnostic; EASD = European Association for the Study of Diabetes FPG = fasting plasma glucose; GA = gestational age; GCI = gestational
carbohydrate intolerance; GCT = glucose tolerance test; GDM = gestational diabetes mellitus; GHT = gestational hypertension; HbA1c = glycated hemoglobin; HBSAg = hepatitis B
virus surface antigen; HOMA = homeostatic model assessment; h = hour; mg = milligrams; IADPSG = International Association of Diabetes and Pregnancy Study Groups; IWC =
International Workshop Conference; JSOG = Japan Society of Obstetrics and Gynecology; CNGOF = National College of French Obstetricians and Gynaecologists; NDDG =
National Diabetes Data Group; NR = not reported; OGTT = oral glucose tolerance test; PCS = prospective cohort study; PIH = pregnancy-induced hypertension; PROM = premature
rupture of the membrane; QUICKI = Quantitative insulin sensitivity check index ; RCS = retrospective cohort study; RF = risk factors; SD = standard deviation; Tx = treatment;
WHO = World Health Organization; wk(s) = week(s); yr(s) = year(s)
Table D2. Characteristics of studies comparing outcomes for women who were and were not screened for GDM, Key Question 2
D-22
Author, year
Women Enrolled, n
Study
Design,
Duration of
Followup
Country
Chanprapaph,
2004
RCS, Until
birth
Maternal Age,
mean± SD (yr)
BMI, mean ± SD
s
(kg/m )
1,000
Screened: 31.5 ±
5.5
Not screened: 24.0
± 3.8
Inclusion/
Exclusion Criteria
Inclusion: Pregnant women
attending a single antenatal care
center; attendance from Oct 2001
to Dec 2002.
Exclusion: NR
Thailand
RCS, Until
birth
93
Screened:
30.5
Not screened:
31.1
Screening Test
First booking;
24 & 28 wks;
30 & 32 wks
Step 1: Risk factors + 50 g OGCT;
positive ≥ 140 mg/dL after 1 hour
Step 2: 100 g OGTT:
1) fasting glucose value 105 mg/dL
2) 1 hr 190 mg/dL
3) 2 hr 165 mg/dL
4) 3 hr 145 mg/dL
-test considered positive if any 2 of
non-fasting values greater than
normal
Screened:
22.5 ± 3.8
Not screened:
20.9 ± 2.9
Solomon,
1996
Gestational Age at Screening
Inclusion: Female nurses; 25 to 42
yrs residing in 1 of 14 US states
Gestational Age: NR
Step 1: 1 h 50 g OGCT
Exclusion: NR
Outcomes
Reported
Numbers screened vs. not screened, n
(%)
Obstetric complications:
PROM: 30 (7) vs. 46 (8)
PIH: 21 (5) vs. 7 (1)
GHT: 4 (1) vs. 4 (1)
CHT: 4 (1) vs. 2 (0.3)
PPH: 3 (1) vs. 1 (0.2)
Chorioamnionitis: 0 (0) vs. 1 (0.2)
Polyhydramnios: 1 (0.2) vs. 0 (0)
Total obstetric complications: 65 (16)
vs. 63 (11)
Pregnancy outcomes:
Preterm delivery: 42 (10) vs. 50 (8)
Birthweight:
th
>90 percentile: 50 (12) vs. 55 (9)
th
<10 percentile: 42(10) vs. 58 (10)
Fetal anomalies: 3 (2) vs. 1 (1)
Cesarean section: 81 (20) vs. 71 (12)
Maternal morbidity: NR
Fetal morbidity:
Macrosomia (7% each group)
US
Screened:
23.0
Not screened:
23.6
* BMI = body mass index; CHT = chronic hypertension; dl = deciliter; DM = diabetes mellitus; GA = gestational age; OGCT = oral glucose tolerance test; GDM = gestational
diabetes mellitus; GHT = gestational hypertension; mg = milligrams; NR = not reported; OGTT = oral glucose tolerance test; PCS = prospective cohort study; PIH = pregnancy –
induced hypertension; PROM = premature rupture of the membrane; RCS = retrospective cohort study; SD = standard deviation; wk = weeks; yr = years
D-23
Table D3. Characteristics of studies examining outcomes of mothers and offspring in the absence of treatment, Key Question 3
Author, year
Study Design
(number of
centers)
Country
Dates of study
Women Analyzed, n
Groups
Aberg, 2001
4,657
RCS (4)
G1: Sub-GDM Group
(no Tx)
G2: Control (no Tx)
Sweden
Maternal
Age, mean ±
SD/ median ±
IQR (yr)
BMI, mean ±
SD/
Median ± IQR
s
(kg/m )
NR
NR
Outcomes
Inclusion
Criteria
Inclusion: Singleton
pregnancy, within Lund
University hospital register,
results matched
Diagnostic Test
Criteria
2 h, 75 g OGTT
WHO, NR
RCS (1)
US
Jan 1986 - Sep
1996
389
G1: GDM Diet (Tx)
G2: GDM Insulin (Tx)
G3: Unrecognized
GDM (no Tx)
G4: Control (no Tx)
Ardawi, 2000
818
PCS (2)
G1: Negative
Screenees (no Tx)
G2: Positive
Screenees (no Tx)
G3: GDM by NDDG
(Tx)
Saudi Arabia
Jun 1996 – Jun
1998
G1: 31.4 ± 4.9
G2: 31.5 ± 4.6
G3: 30.2 ± 4.7
G4: 30.2 ± 4.5
Inclusion: Positive OGCT;
meets NDDG criteria (2
plasma glucose values on
OGTT) for GDM
1 h, 50 g OGCT
3 h, 100 g
OGTT
G1: 26.1 ± 6.1
G2: 30.3 ± 7.2
G3: 26.6 ± 7.5
G4: 26.3 ± 7.0
Exclusion: Multiple
gestation; fetal congenital
anomalies; delivery before
34 wks; delivery elsewhere;
diet or insulin therapy
initiated < 4 wks before
delivery
NDDG, 1979
G1: 29.2 ± 4.6
G2: 30.7 ± 4.8
G3: 32.1 ± 5.1
G1: 64.3 ± 4.1
G2: 68.6 ± 4.1
G3: 75.2 ± 4.5
Inclusion: NR
Exclusion: Hepatic renal
disease, DM prior to
pregnancy, previous diet
therapy, previous GDM,
known endocrine disorders
D-24
Emergency cesarean delivery,
elective cesarean delivery,
perinatal mortality rate
Other: Gestational duration, birth
weight, umbilical artery pH,
APGAR score
Exclusion: NR
Jan 1995 - Dec
1997
Adams,1998
Other Outcomes (Not defined
by KQ)
1 h, 50 g OGCT
3 h, 100 g
OGTT
Cesarean delivery, maternal weight
gain, maternal birth trauma
(rectal injury), macrosomia (BW
>4000 gm, >4500 gm), shoulder
dystocia, clavicular fracture,
brachial plexus injury (cranial
nerve palsy, brachial plexus,
permanent & healed),
hypoglycemia, hyperbilirubinemia
(within neonatal complications
composite), mortality (stillbirth)
Other: Birthweight, LGA, vacuum
& forceps delivery
Cesarean delivery, macrosomia,
hypoglycemia,
hyperbilirubinemia,
mortality(stillbirth)
NDDG 1979
Other: Fetal length, <25g, head
circumference, wk at delivery
Author, year
Study Design
(number of
centers)
Country
Dates of study
Women Analyzed, n
Groups
Berggren, 2001
3,759
RCS (1)
G1: CC GDM (no Tx)
G2: NDDG GDM (Tx)
G3: Control (no Tx)
US
Maternal
Age, mean ±
SD/ median ±
IQR (yr)
BMI, mean ±
SD/
Median ± IQR
s
(kg/m )
NR
833
RCS (NR)
G1: GDM by CC (no
Tx)
G2: GDM by Sacks
(no Tx)
G3: GDM by Langer
(no Tx)
G4: Normal (no Tx)
US
1987 – 1988
Biri, 2009
2,029
RCS (1)
G1: Normal 50 g GLT
(no Tx)
G2: Abnormal 50 g/
Normal 100 g (no Tx)
G3: 1 Abnormal 100 g
(no Tx)
G4: GDM - 100 g GLT
(Tx)
G5: GDM – 50 g GLT
(no Tx)
Turkey
Jan 2004 - Dec
2006
Inclusion
Criteria
Inclusion: Delivery at UNC
women’s hospital
NR
Exclusion: No results
available on 1 hr 50 g
OGCT, delivery <24 wks,
pregestational DM, GDM
diagnosed by 50 g OGCT
only
Apr 1996 – May
2010
Berkus, 1995
Outcomes
G1: 29.0 ± 5.0
G2: 30.0 ± 7.0
G3: 29.0 ± 6.0
G4: 26.0 ± 6.0
Inclusion: Nonhypertensive
gravidas; singleton
pregnancy; underwent 3hour GTT; attended clinics
in San Antonio area
1 h, 50 g OGCT
3 h, 100 g
OGTT
NDDG 1979
CC 1982
No OGCT
3 h, 100 g
OGTT
Other Outcomes (Not defined
by KQ)
Preeclampsia, Maternal
Hypertension, Cesarean delivery,
maternal birth trauma (3rd or 4th
degree laceration), macrosomia,
shoulder dystocia
Other: GA at delivery, mode of
delivery other than c-section,
HELLP (hemolysis, elevated liver
enzymes, low platelet count),
birthweight, NICU admission,
NICU stay >48 hrs
Macrosomia
Other: Birthweight
Exclusion: Women with 2+
abnormal OGTT values by
NDDG criteria
Coustan &
Lewis, 1978
NDDG, 1979
Langer,1987
Sacks,1989
Inclusion: Singleton
pregnancies, screened at
study centre
1 h, 50 g OGCT
3 h, 100 g
OGTT
Preeclampsia, cesarean delivery,
macrosomia, hypoglycemia,
hyperbilirubinemia
Exclusion: Prepregnancy
DM, multiple gestations
ACOG, 2001
NDDG, 1979
Other: Birthweight, LGA/SGA,
APGAR, respiratory
complications, polyhydramnios,
prematurity
NR
G1: 29.6 ± 4.6
G2: 30.9 ± 4.9
G3: 32.1 ± 4.6
G4: 33.3 ± 4.8
G5: 32.6 ± 5.0
Diagnostic Test
Criteria
NR
D-25
Author, year
Study Design
(number of
centers)
Country
Dates of study
Women Analyzed, n
Groups
Black, 2010
8,711
RCS (1)
All no Tx
G1: No GDM
G2: IGT
G3: IFG
G4: IGT-2
G5: IFG-IGT
US
Oct 2005 – Mar
2010
Bo, 2004
RCS (1)
Italy
Apr 1999 - Feb
2001
700
G1: OGCT negative
(normal) (no Tx)
G2: OGCT positive
OGTT negative (no
Tx)
G3: OGTT1 abnormal
value (Tx)
G4: GDM positive (Tx)
Maternal
Age, mean ±
SD/ median ±
IQR (yr)
BMI, mean ±
SD/
Median ± IQR
s
(kg/m )
G1: 28.6 ± 5.9
G2: 32.1 ± 5.4
G3: 30.4 ± 5.6
G4: 32.3 ± 5.2
G5: 32.0 ± 5.1
G1: 26.9 ± 5.8
G2: 28.1 ± 5.6
G3: 30.8 ± 7.1
G4: 27.5 ± 4.7
G5: 31.8 ± 7.0
G1: 30.8 ± 4.2
G2: 31.8 ± 4.3
G3: 32.9 ± 4.7
G4: 32.6 ± 4.9
NR
Cheng, 2009
1,469
NR
RCS (1)
G1: No GDM (no Tx)
G2: GDM by CC only
(no Tx)
G3: GDM NDDG only
(Tx)
NR
US
Jan 1988 - Dec
2001
Outcomes
Inclusion
Criteria
Inclusion: Singleton birth
>20 wks gestation, received
2 hr 75 g OGTT with no
prior 50 g OGCT, available
pre-pregnancy and delivery
anthropometric data
Diagnostic Test
Criteria
2 h, 75 g OGTT
IADPSG, 2010
Cesarean delivery, maternal
weight gain, gestational
hypertension, shoulder
dystocia/birth injury,
hyperbilirubinemia
Other: Birthweight, LGA,
ponderal index, preterm delivery
Exclusion: Any form of
treatment
Inclusion: Caucasian;
attending clinic
Other Outcomes (Not defined
by KQ)
1 h, 50 g OGCT
3 h, 100 g
OGTT
Cesarean delivery, macrosomia,
hyperbilirubinemia (icterus),
mortality (death)
Exclusion: Known DM, any
disease affecting glucose
metabolism
CC, 1982
Inclusion: All pregnancies
screened and delivered at
University of California
1 h, 50 g OGCT
3 h, 100 g
OGTT
Exclusion: Multifetal
pregnancies, vaginal
breech deliveries, delivery
<24 wks, congenital
anomalies, pregestational
DM
NDDG,1979
CC, 1982
Other: "Metabolic Syndrome in
Pregnancy", premature births,
birthweight, LGA/SGA, APGAR
score, respiratory distress,
malformations, neonatal
diseases
Preeclampsia, cesarean delivery
(mode of delivery), maternal birth
trauma (3rd or 4th degree
laceration), macrosomia,
shoulder dystocia, birth trauma
composite variable incl. brachial
plexus injury, facial nerve palsy,
clavicular and skull fracture,
head laceration
Other: Preterm delivery <37wks,
APGAR <7, neonatal acidemia,
LGA
D-26
Author, year
Study Design
(number of
centers)
Country
Dates of study
Women Analyzed, n
Groups
Chico, 2005
6,248
RCS (1)
G1: Standard criteria
(Tx)
G2: New criteria (Tx)
G3: Subgroup- New
IGT criteria (no Tx)
G4: Normal tolerance
(no Tx)
Spain
Jan 1999 - Dec
2001
Chou, 2010
10,990
RCS (1)
Jan 2001 - Sep
2008
G1: Normal (no Tx)
G2: GDM by CC but
not NDDG criteria (no
Tx)
G3: GDM by NDDG
criteria (Tx)
Cok, 2011
185
RCS(1)
G1: 0h OGTT (no Tx)
G2: 1 h OGTT (no Tx)
G3: 2 h OGTT (no Tx)
G4: 3 h OGTT (no Tx)
Taiwan
Turkey
Jan 2003 - Jun
2009
Corrado, 2009
776
RCS (NR)
G1: OAV (no Tx)
G2: Control (no Tx)
Italy
Maternal
Age, mean ±
SD/ median ±
IQR (yr)
BMI, mean ±
SD/
Median ± IQR
s
(kg/m )
G1: 33.4 ± 4.0
G2: 33.3 ± 4.0
G3: 33.3 ± 4.0
G4: 32.8 ± 4.0
Outcomes
Inclusion
Criteria
Inclusion: All pregnancies
handled in 2 yr period
Diagnostic Test
Criteria
1 h, 50 g OGCT
3 h, 100 g
OGTT
Exclusion: None
NR
NDDG, 1979
th
4 IWC/ADA,
2003
th
4 IWC/CC,
1998
1 h, 50 g OGCT
3 h, 100 g
OGTT
G1: 32.8 ± NR
G2: 33.4 ± NR
G3: 34.4 ± NR
Inclusion: Singleton
pregnancies delivered at
Cathay General Hospital
NR
Exclusion: Multiple
pregnancies, fetal
anomalies diagnosed
prenatally
CC, 1982
NDDG, 1979
G1: 32.5 ± 4.8
G2: 30.1 ± 4.5
G3: 30.0 ± 5.1
G4: 30.2 ± 4.3
Inclusion: Women
presenting to Baskent
Unviersity, one abnormal
OGTT value
1 h, 50 g OGCT
3 h, 100 g
OGTT
G1: 33.7 ± 4.5
G2: 30.8 ± 3.8
G3: 29.8 ± 4.3
G4: 30.1 ± 3.2
Exclusion: Multiple
gestations or prepregnancy
DM, 2 abnormal OGTT
values
G1: 31.2 ± 5.1
G2: 30.1 ± 4.9
Inclusion: Caucasian, one
positive screening test and
OGTT
1 h, 50 g OGCT
3 h, 100 g
OGTT
Exclusion: Multiple
gestations, Tx for GDM
CC, 1982
Other Outcomes (Not defined
by KQ)
Cesarean delivery, maternal
weight gain, macrosomia (>4000
g), hypoglycemia,
hyperbilirubinemia (jaundice),
mortality (fetal deaths)
Other: Week of delivery,
instrumentation, birthweight,
LGA/SGA, APGAR,
malformations
Maternal hypertension, cesarean
delivery, maternal birth trauma
(postpartum hemorrhage),
macrosomia, shoulder dystocia,
mortality (intrauterine fetal
demise)
Other: Preterm labour, APGAR
scores
Macrosomia
Other: LGA, birthweight, birth
week
CC, 1982
G1: 25.0 ± 5.1
G2: 24.2 ± 4.4
D-27
Preeclampsia/maternal
hypertension (hypertensive
disorders of pregnancy),
cesarean delivery, macrosomia,
hypoglycemia
Author, year
Study Design
(number of
centers)
Country
Dates of study
Jan 1996 - Dec
2005
Hillier, 2007
RCS (2)
US
1995-2000
Jensen, 2002
RCS(4)
Denmark
Jan 1992 - Dec
1996
Kim, 2002
PCS(1)
South Korea
NR
Women Analyzed, n
Groups
Maternal
Age, mean ±
SD/ median ±
IQR (yr)
BMI, mean ±
SD/
Median ± IQR
s
(kg/m )
Outcomes
Inclusion
Criteria
Diagnostic Test
Criteria
Other: GA, birthweight, APGAR
(insulin/diet)
9,439
NR
G1: Normal (no Tx)
G2: Positive OGCT
normal OGTT (no Tx)
G3: Positive OGCT
and 1 Abnormal CC or
NDDG (no Tx)
G4: GDM-CC (no Tx),
G5: GDM NDDG (Tx)
3,260
NR
G1: Normal WHO (no
Tx)
G2: Normal DPSG but
IGT WHO (no Tx)
G3: Abnormal DPSG
and IGT WHO (Tx)
G4: GDM by both (Tx)
699
NR
G1: Normal (no
elevated)
G2: 1 Elevated (1 h
elevated)
G3: 2 Elevated (2 h
elevated)
G4: 3 Elevated (3 h
elevated)
Inclusion: Data on motherchild pairs 5-7 yrs PP
Other Outcomes (Not defined
by KQ)
1 h, 50 g OGCT
3 h, 100 g
OGTT
Macrosomia (maternal glycemic
level associated with
macrosomia, childhood obesity)
NDDG, NR
(1979)
CC criteria as
presented in
th
4 IWC, 1998
Other: Prevalence, risk of
childhood obesity; association
with maternal GDM screening
results during pregnancy
(hyperglycemia)
2 h, 75 g OGTT
Preeclampsia, maternal
hypertension, cesarean delivery,
maternal weight gain,
macrosomia (>4000g),
hypoglycemia, hyperbilirubinemia
(jaundice)
Exclusion: Preexisting DM
NR
Inclusion: First pregnancy in
study period, tested with 75
g OGTT
WHO, 1985
DPSG, 1991
Exclusion: Pregestational
GDM, multiple pregnancies,
chronic disease
G1: 30.7 ± 3.9
G2: 29.5 ± 4.4
G3: 30.2 ± 3.3
G4: 32.3 ± 3.8
G1: 21.4 ± 2.9
G2: 21.0 ± 3.0
G3: 20.7 ± 2.6
G4: 21.8 ± 2.8
Inclusion: singleton
pregnancy; antenatal care
at Ajou University Hospital
Department of Obstetrics
and Gynecology
Exclusion: missing data;
confirmed GDM dx
D-28
1 h, 50 g OGCT
3 h, 100 g
OGTT
Other: LGA, respiratory distress,
preterm delivery, glucosuria, GA
Preeclampsia, cesarean delivery,
th
birthweight, LGA 90 percentile
(macrosomia), hypoglycemia,
perinatal death
NDDG, NR
Other: Gestational age at birth
(wks), APGAR, respiratory
distress syndrome, poor perinatal
outcome
Author, year
Study Design
(number of
centers)
Country
Dates of study
Kwik,
2007
RCS(1)
Women Analyzed, n
Groups
675
G1: Treated
G2: Untreated
G3: Comparison
Australia
Feb 2000/Oct
2003 - May 2005
Landon,
2009 (primary)
Landon, 2011
RCT(Multicenter,
n = NR)
US
Oct 2002 - Nov
2007
1,841
G1: CC Mild GDM (no
Tx)
G2: CC False-positive,
further divided by
normal/ abnormal
OGTT value (no Tx,
no distinct data)
G3: Normal control
(no Tx)
Maternal
Age, mean ±
SD/ median ±
IQR (yr)
BMI, mean ±
SD/
Median ± IQR
s
(kg/m )
G1: 34.5 ± 4.8
G2: 33.3 ± 4.7
G3: 32.8 ± 4.5
G1: 23.8 ± 4.4
G2: 22.9 ± 4.6
G3: 22.6 ± 3.7
G1: 28.9 ± 5.6
G2: 27.4 ± 5.5
G3: 25.1 ± 5.3
G1: 30.2 ± 5.1
G2: 30.1 ± 5.3
G3: 29.9 ± 5.8
Outcomes
Inclusion
Criteria
Inclusion: Singleton
pregnancy, 75 g GTT with a
fasting value ≤ 5.5 mmol/L
and 2-h blood sugar ≥7.8
mmol/L
Diagnostic Test
Criteria
1 h, 50 g OGCT
2 h, 75 g OGTT
ADA, 2000
Exclusion: Confined ≤34 wks
gestation
Inclusion: Between 24 wks 0
ds and 30 wks 6 ds
gestation, 135 and 200
mg/dL 1 hour after a 50 g
glucose loading test
Exclusion: Preexisting
diabetes, abnormal results
before 24 wks, prior GDM,
Hx of stillbirth, multifetal
gestation, asthma, CHT,
corticosteriod use, known
fetal anomaly, likely
preterm delivery
D-29
1 h, 50 g OGCT
3 h, 100 g
OGTT
CC, 1982
th
4 IWC, 1998
Other Outcomes (Not defined
by KQ)
Preeclampsia, cesarean delivery,
macrosomia (BW > 4000 g),
shoulder dystocia, clavicular
fracture, brachial plexus injury
(Erb's Palsy)
Other: Mean birthweight, SCN
admission, APGAR, premature
delivery, GA at delivery
Preeclampsia, maternal
hypertension, cesarean delivery,
maternal weight gain,
macrosomia (BW >4000 g),
shoulder dystocia, birth injury
(trauma), hypoglycemia,
hyperbilirubinemia, mortality
(stillbirth/neonatal death)
Other: GA at birth, elevated c-cord
peptide, birthweight, LGA/SGA,
Fat mass, Preterm delivery,
NICU admission, IV glucose Tx,
respiratory distress
Author, year
Study Design
(number of
centers)
Country
Dates of study
Women Analyzed, n
Groups
Langer, 2005
2,775
US(1)
G1: GDM (no Tx, Dx
after 37 wks)
G2: GDM (Tx)
G3: Nondiabetic
control (no Tx)
RCS
Maternal
Age, mean ±
SD/ median ±
IQR (yr)
BMI, mean ±
SD/
Median ± IQR
s
(kg/m )
G1: 27.6 ± 6.0
G2: 29.1 ± 6.0
G3: 25.0 ± 6.0
NR
Jan 1999 - Sept
1999
Lao, 2001
487
PCS(1)
NR
G1: GDM by WHO
(Tx)
G2: Normal OGTT
only (no Tx)
G3: Control (no Tx)
Lao, 2003
2,149
RCS(1)
2 h OGTT (mmol/L):
G1: <6.0 (no Tx)
G2: 6.0 -6.9 (no Tx)
G3: 7.0 -7.9 (no Tx)
China
China
1996 – 1997
G1: 32.1 ± 4.6
G2: 30.4 ± 5.3
G3: 27.7 ± 4.0
G1: 22.6 ± 3.2
G2: 22.0 ± 2.7
G3: 21.1 ± 2.7
G1: 28.6 ± 4.6
G2: 29.6 ± 4.6
G3: 30.8 ± 4.4
G1: 21.5 ± 2.6
G2: 21.7 ± 2.7
G3: 21.8 ± 2.8
Outcomes
Inclusion
Criteria
Inclusion: Singleton
pregnancies, FPG<140
mg/dL on OGTT; Casecontrol groups: GDM
diagnosed >37 wks, treated
GDM and non diabetic
matched 2:1 for obesity,
parity, ethnicity, GA at
delivery (within 5 ds), yr of
delivery
Exclusion: Pregestational
DM, substance abusers,
multifetal gestation, fetal
anomalies
Inclusion: Singleton
pregnancies with visits to
antenatal care between 2830 wks
Exclusion: Preexisting DM,
CHT or other medical
complication, thalassemia
trait
Inclusion: Singleton
pregnancy, antenatal
OGTT, delivery at Queen
Mary hospital, no insulin
requirements
Exclusion: Significant
medical complications,
taking no medication (ie.
corticosteriods)
D-30
Diagnostic Test
Criteria
1 h, 50 g OGCT
3 h, 100 g
OGTT
Other Outcomes (Not defined
by KQ)
Cesarean delivery, macrosomia,
shoulder dystocia, hypoglycemia,
hyperbilirubinemia, mortality
(stillbirth)
CC, 1982
Other: Birthweight, LGA, ponderal
Index >2.85, arterial cord pH
<7.2, erythrocytosis, respiratory
complication, induction of labour
2 h, 75 g OGTT
WHO, 1980
Preeclampsia, cesarean delivery,
maternal birth trauma
(antepartum hemorrhage)
Other: Preterm labor, prelabor
rupture of the membranes,
delivery mode, weeks gestation,
birthweight, LGA/SGA, APGAR
score 1 min., NICU admission
Cesarean delivery, macrosomia
2 h, 75 g OGTT
WHO, 1980
Other: Birthweight, LGA/SGA,
preterm birth
Author, year
Study Design
(number of
centers)
Country
Dates of study
Women Analyzed, n
Groups
Lapolla, 2007
611
PCS(5)
G1: Normal Control
(no Tx)
G2: False Positive (no
Tx)
G3: 1 Abnormal
Glucose Value (OAV)
(no Tx)
G4: GDM (Tx)
1,927
Italy
NR
Lapolla, 2011
RCS(1)
Italy
G1: GDM formerly
normal (no Tx)
G2: Normal (no Tx)
Maternal
Age, mean ±
SD/ median ±
IQR (yr)
BMI, mean ±
SD/
Median ± IQR
s
(kg/m )
G1: 30.9 ± 4.7
G2: 31.7 ± 4.9
G3: 32.5 ± 4.4
G4: 33.4 ± 4.4
Outcomes
Inclusion
Criteria
Diagnostic Test
Criteria
Inclusion: No smoking; no
CHT/specific conditions
known to affect glucose
metabolism
1 h, 50 g OGCT
3 h, 100 g
OGTT
HbA1c*
G1: 22.4 ± 4.2
G2: 22.8 ± 3.9
G3: 23.7 ± 4.7
G4: 24.7 ± 4.8
Exclusion: Those with
conditions known to affect
glucose metabolism
G1: 32.4 ± 4.5
G2: 32.2 ± 4.5
Inclusion: Positive 50 g
OGCT (1-h plasma glucose
≥ 7.8mmol/L), 3-h OGTT at
24–28 wks; negative result
on OGCT or OGTT formed
control group
Criteria not
defined, values
same as
CarpenterCoustan
1 h, 50 g OGCT
3 h, 100 g
OGTT
G1: 23.7 ± 4.3
G2: 23.3 ± 4.2
IADPSG, 2010
th
4 IWC, 1998
1998 - 2008
Other Outcomes (Not defined
by KQ)
Cesarean delivery, macrosomia
Other: LGA, ponderal index
Maternal morbidity (eclampsia),
maternal hypertension, cesarean
delivery, macrosomia, shoulder
dystocia (within fetal morbidity,
incl. malformations,
hypoglycemia,asphyxia,hyperbilir
ubinemia, etc.)
Exclusion: NR
Metzger/
HAPO, 2008
PCS(15)
Various
Jul 2000 - Apr
2006
23,316
(All no Tx)
G1: 100 mg/dL +
G2: 95-99 mg/dL
G3: 90-94mg/dL
G4: 85-89mg/dL
G5: <85mg/dL;
subdivided into
G6: <75mg/dL
G7: 75-79 mg/dL
Tot: 29.2 ±
5.8
Tot: 27.7 ±
5.1
Inclusion: Pregnant women
2 h, 75 g OGTT
Exclusion: <18 years,
unknown LMP, no
ultrasonographic estimation
of GA between 6-24 wks,
no OGTT within 32 wks,
multiple pregnancies,
assisted conception/IVF,
glucose testing before
recruitment, participation in
another study or previous
HAPO study, HIV, hepatitis
B or C virus; no English
language proficiency
HAPO Criteria;
defined by
groups
D-31
Other: LGA/SGA, birthweight,
ponderal index
Preeclampsia, maternal
hypertension, cesarean delivery,
shoulder dystocia, hypoglycemia,
hyperbilirubinemia
Other: Cord blood serum Cpeptide, Cord blood PG, CHT,
intensive neonatal care,
premature delivery, BW >90th
percentile
Author, year
Study Design
(number of
centers)
Country
Dates of study
Women Analyzed, n
Groups
Morikawa, 2010
228
RCS(1)
G1: JSOG GDM (Tx)
G2: JSOG - No GDM
(no Tx)
G3: IADPSGHyperglycemia (Tx)
G4: IADPSG-New
Patients (no Tx)
G5: IADPSG No GDM
(no Tx)
614
Japan
Jan 2002- Dec
2006
Nord, 1995
RCS(2)
Sweden
1989 -1990
G1: 2-h OGTT 8.08.9mmol/L (no Tx)
G2: Controls (no Tx)
Maternal
Age, mean ±
SD/ median ±
IQR (yr)
BMI, mean ±
SD/
Median ± IQR
s
(kg/m )
NR
NR
Outcomes
Inclusion
Criteria
Inclusion: Women with both
OGCT and OGTT;
singleton birth
Exclusion: NR
G1: 30 ± 1846
G2: 29 ± 1645
G1: 22.3 ±
17.0 -43.3
G2: 21.3 ±
16.0-41.8
Inclusion: Intervention
group: Indications to
perform OGTT (Hx of DM in
first degree relative; obesity
(≥120 % or >9 kg);
previous LFD-baby (>4.5
kg); IGT in previous
pregnancy; accelerated
fetal growth or
polyhydraminosis;
glucosuria; random Bglucose ≥7. mmol/L).
Control group: No
indication to perform OGTT
Exclusion: NR
D-32
Diagnostic Test
Criteria
1 h, 50 g OGCT
2 h, 75 g OGTT
Other Outcomes (Not defined
by KQ)
Macrosomia
Other: BW percentile
IADPSG, 2010
JSOG, 2008
2 h, 75 g OGTT
WHO, 1980
Preeclampsia, cesarean delivery,
macrosomia (LFD - large for
date), clavicular facture, brachial
plexus injury, birth injury
(traumatic delivery),
hypoglycemia,
hyperbilirubinemia, mortality
Other: Premature delivery,
respiratory distress syndrome,
polycythemia requiring Tx,
traumatic delivery
Author, year
Study Design
(number of
centers)
Country
Dates of study
Women Analyzed, n
Groups
Maternal
Age, mean ±
SD/ median ±
IQR (yr)
Pennison, 2001
242
BMI, mean ±
SD/
Median ± IQR
s
(kg/m )
NR
RCS (1)
G1: Control (no Tx)
G2: GDM NDDG (Tx)
G3: GDM ADA (no Tx)
G1: 30.2 ± 1.1
G2: 31.7 ± 1.0
G3: 29.6 ± 1.1
US
Outcomes
Inclusion
Criteria
396
PCS (Multicenter,
n = NR)
2003 - Sep 2007
G1: Normal OGCT,
NGT (no Tx)
G2: Abnormal OGCT,
NGT (no Tx)
G3: GIGT (no Tx)
G4: GDM (Tx)
Ricart, 2005
9270
PCS (16)
G1: NDDG GDM (Tx),
G2: NDDG Negative
(No Tx),
G3: False-positive
ADA (No Tx),
G4: ADA GDM (No
Tx)
Canada
Spain
1 h, 50 g OGCT
3 h, 100 g
OGTT
Preeclampsia, cesarean delivery,
macrosomia, shoulder dystocia,
hypoglycemia
Exclusion: NR
ADA, 1998
CC, 1982
NDDG/ACOG,
1994
1 h, 50 g OGCT
3 h, 100 g
OGTT
3 mo. PP:
2 h, 75 g OGTT
Maternal weight gain
2002 - NR
G1: 34.0 ± 4.4
G2: 33.8 ± 4.2
G3: 34.2 ± 4.2
G4: 34.5 ± 4.3
Inclusion: Attending
outpatient obstetrics clinics;
late second trimester; 50 g
OGCT screen
G1: 23.0 ±
21.5-26.1
G2: 23.5 ±
21.1-27.5
G3: 23.5 ±
21.8-27.7
G4: 25.0 ±
22.0-30.1
G1: 31.9 ± 4.7
G2: 28.8 ± 5.3
G3: 30.5 ± 4.9
G4: 31.7 ± 4.6
Exclusion: NR
G1: 25.9 ± 5.2
G2: 23.5 ± 3.9
G3: 24.5 ± 4.5
G4: 25.2 ± 4.7
Other Outcomes (Not defined
by KQ)
Inclusion: Delivery at
regional medical centre in
Memphis; euglycemic or Dx
GDM
1995 - 1999
Retnakaran, 2008
Diagnostic Test
Criteria
Other: 3 mo postpartum: maternal
insulin sensitivity, beta-cell
function, glycemia
NDDG 1979,
CDA 2003
Inclusion: Singleton
pregnancy, no former Dx of
GDM
1 h, 50g OGCT
3 h, 100g
OGTT
Cesarean delivery, pregnancy
induced hypertension, perinatal
mortality, macrosomia
Exclusion: Women who did
not undergo screening,
unavailable results
ADA, 2000
NDDG, 1979
Other: Preterm birth, LGA/SGA,
APGAR score 1 & 5 mins, major
malformations
D-33
Author, year
Study Design
(number of
centers)
Country
Dates of study
Women Analyzed, n
Groups
Rust, 1996
664
RCS(1)
G1: ≥ 2 of 4 values,
abnormal by Sacks
criteria
G2: ≥ 2 of 4 values,
abnormal by CC
criteria
G3: 1 abnormal by
Sacks
G4: 1 abnormal by CC
G5: No abnormal by
Sacks
G6: No abnormal by
CC
US
NR - NR
Sacks,1995
3,505
PCS(NR)
Groups: Women were
not grouped; actual
glucose levels were
used in regression
analyses to assess
the association with
birthweight
US
Mar 1992 - Mar
1993
Maternal
Age, mean ±
SD/ median ±
IQR (yr)
BMI, mean ±
SD/
Median ± IQR
s
(kg/m )
G1: 25.7 ± NR
G2: 23.7 ± NR
G3: 22.7 ± NR
G4: 26.7 ± NR
G5: 24.0 ± NR
G6: 22.7 ± NR
Outcomes
Inclusion
Criteria
Inclusion: Positive GDM
screen result; underwent 3
h100 g OGT
Exclusion: Delivery outside
study hospital
G1: 26.6 ± NR
G2: 25.5 ± NR
G3: 24.8 ± NR
G4: 28.1 ± NR
G5: 25.7 ± NR
G6: 24.6 ± NR
Tot: 27.2 ±
5.8
Inclusion: Enrolled in
prenatal care
Tot: 24.9 ±
NR
Exclusion: GDM in previous
pregnancy, glucocorticoids,
diet or insulin Tx, high
fasting plasma glucose
values, multiple gestations
D-34
Diagnostic Test
Criteria
1 h, 50 g
OGCT
3 h, 100 g
OGTT
CC,1982
NDDG,1979
O'Sullivan and
Mahan,1964
Sacks, 1975
2 h, 75 g OGTT
No criteria
defined,
purpose of
study to ID
threshold
values
Other Outcomes (Not defined
by KQ)
Maternal hypertension,cesarean
delivery, birth trauma (obstetric
lacerations, hemorrhage)
maternal weight gain,
macrosomia, shoulder dystocia,
birth trauma (dystocia disorders,
birth trauma), hypoglycemia,
hyperbilirubinemia, mortality
(cumulative neonatal morbidity)
Other: Intrauterine growth
restriction, oligohydramnios,
preterm labor, premature or
prolonged rupture of the
membranes, chorioamnionitis,
malpresentation, labour
induction, labour augmentation,
fetal intolerance of labour,
abdominal delivery, operative
vaginal delivery
Maternal weight gain, macrosomia
Author, year
Study Design
(number of
centers)
Country
Dates of study
Schwartz,
1999
RCS(4)
US
1995 - 1996
Sermer,
1995 (Primary)
Naylor, 1996
RCT(3)
Canada
Sep 1989 - Mar
1992
Shirazian, 2008
PCS(5)
Iran
NR - NR
Women Analyzed, n
Groups
8,711
G1: Normal results,
prenatal screen (no
Tx)
G2: Abnormal (or no)
prenatal screen and
normal OGTT (no Tx)
G3: NDDG GDM (Tx)
G4: CC GDM (no Tx)
3,780
G1: Negative
screenees (no Tx),
G2: False-positive
Screenees (no Tx)
G3: GDM- Borderline
(no Tx)
G4: GDM (Tx)
Maternal
Age, mean ±
SD/ median ±
IQR (yr)
BMI, mean ±
SD/
Median ± IQR
s
(kg/m )
NR
Outcomes
Inclusion
Criteria
Inclusion: No previous DM
or GDM
NR
Diagnostic Test
Criteria
1 h, 50 g OGCT
3 h, 100 g
OGTT
Other Outcomes (Not defined
by KQ)
Cesarean delivery, macrosomia
(BW >4000 g , >4500 g),
mortality (stillbirth)
Exclusion: NR
CC, 1982
NDDG, 1979
G1: 30.9 ± 4.1
G2: 31.9 ± 4.3
G3: 32.1 ± 4.4
G4: 32.7 ± 4.3
G1: 22.7 ± 3.8
G2: 23.1 ± 4.5
G3: 24.7 ± 5.8
G4: 24.2 ± 4.8
Inclusion: >24 yrs at
delivery; no Hx of
preexisting DM; examined
by physician before 24 wks
gestation
1 h, 50 g OGCT
3 h,100 g
OGTT
NDDG, 1979
CC, 1982
Exclusion: Delivery <28 wks
612
NR
Inclusion: No Hx of DM
2 h, 75 g OGTT
G1: No GDM (no Tx)
G2: GDM by ADA only
(Tx)
G3: GDM by WHO
only (NR)
G4: GDM by ADIPS
only (NR)
Tot: 24.4 ± 4.6
Exclusion: Pregestational
DM, inablity to complete
OGTT at 24-48 wks, twin
pregnancies, no CHT,
chronic renal failure, heart
diseases, advanced
pulmonary disease, current
th
smokers, labor before 37
th
or after 40 gestational wk,
planning to deliver at
another hospital
ADA, 2008
WHO, 2008
ADIPS, 2008
D-35
Preeclampsia, cesarean delivery,
macrosomia, hypoglycemia,
hyperbilirubinemia
(phototherapy)
Other: Fetal trauma, congenital
anomalies, respiratory distress
syndrome, maternal/fetal length
of stay
Macrosomia
Author, year
Study Design
(number of
centers)
Country
Dates of study
Stamilio,
2004
RCS(1)
US
Women Analyzed, n
Groups
1,825
G1: False-positive
OGCT (no Tx)
G2: Negative OGCT
(no Tx)
G3: GDM (Tx)
Maternal
Age, mean ±
SD/ median ±
IQR (yr)
BMI, mean ±
SD/
Median ± IQR
s
(kg/m )
G1: 28.5 ± NR
G2: 25.5 ± NR
G1: 28.5 ± NR
G2: 25.5 ± NR
Tan, 2008
1,200
RCS(1)
G1: Negative OGCT
(no Tx)
G2: False-Positive
OGCT (no Tx)
G1: 28.9 ± 4.6
G2: 30.3 ± 4.7
G1: 26.5 ±4.4
G2: 27.0 ± 4.4
Vambergue, 2000
239
PCS(15)
G1: Mild Gestational
Hyperglycemia (MGH)
(no Tx)
G2: Control (no Tx)
Feb 1992 - Sep
1992
Inclusion: Delivery at
University of Pennsylvania
Medical Center, entry into
triple marker screen
perinatal database,
complete followup
Diagnostic Test
Criteria
1 h, 50 g OGCT
3 h, 100 g
OGTT
NDDG modified
by O’Sullivan
cutoff, NR
Inclusion: GCT screen at
prenatal booking, GTT test
only of GCT was positive,
available delivery records
1 h, 50 g OGCT
2 h, 75 g OGTT
G1: 28.8 ± 5.8
G2: 27.0 ± 5.2
Inclusion: Attendance at
public maternity unit
G1: 24.8 ± 4.8
G2: 23.0 ± 3.9
Exclusion: Twin
pregnancies, prepregnancy high blood
pressure, asthma,
haemochromatosis, prepregnancy diabetes or
GDM
D-36
Other Outcomes (Not defined
by KQ)
Preeclampsia, maternal
hypertension (chronic
hypertension), long term
hypertension (chronic
hypertension), macrosomia,
shoulder dystocia, mortality
(antenatal death)
Other: NICU admission,
chorioamionitis, endometritis,
birthweight (mean), high 28-week
mean arterial pressure
(maternal)
Cesarean delivery, maternal birth
trauma (hemorrhage),
macrosomia, SGA, fetal loss
WHO, 1999
Other: Preterm birth, induction of
labor, APGAR, cord blood ph
Exclusion: Women missing
GTT despite positive GCT,
multiple gestations
Jan 2006 - July
2006
France
Inclusion
Criteria
Exclusion: Multiple
gestations, anomalous
fetuses
1995 -1997
Malaysia
Outcomes
1 h, 50 g OGCT
3 h, 100 g
OGTT
CC, 1982
Pregancy induced hypertension,
cesarean delivery, shoulder
dystocia, macrosomia,
hypoglycemia,
hyperbilirubinemia, mortality
Other: LGA/SGA, respiratory
distress, pathological deliveries,
transfer to neonatal care unit,
malformations, prematurity,
APGAR score, adverse maternal
and fetal outcome
Author, year
Study Design
(number of
centers)
Country
Dates of study
Women Analyzed, n
Groups
Yang, 2002
404
PCS(16)
G1: Impaired Glucose
Tolerance (no Tx)
G2: Normal (Normal
Glucose Tolerance (no
Tx)
China
Dec 1998 - Dec
1999
Maternal
Age, mean ±
SD/ median ±
IQR (yr)
BMI, mean ±
SD/
Median ± IQR
s
(kg/m )
G1: 28.0 ±
3.68
G2: 26.5 ±
2.95
G1: 22.6 ±
3.49
G2: 21.5 ±
2.57
Outcomes
Inclusion
Criteria
Diagnostic Test
Criteria
Inclusion: NR
Exclusion: <18 yrs, multiple
pregnancies, maternal-fetal
ABO incompatibility,
maternal disease incl.
prepregnancy diabeetes &
those under long term
medical treatment that may
affect glucose metabolism,
delivery outside Tianjin
(rural or home delivery)
1 h, 50 g OGCT
2 h, 75 g OGTT
WHO, 1998
Other Outcomes (Not defined
by KQ)
Weight gain in pregnancy,
cesarean delivery, birth
trauma/dystocia, mild/moderate
th
preeclampsia, birthweight > 90
percentile (macrosomia),
th
birthweight > 95 percentile,
hypoglycemia, perinatal death
Other: PROM, breech
presentation, preterm delivery,
fetal male gender, low birth
weight (< 2500 g), APGAR score
< 7 @ 1 min, pneumonia
* ACOG = American Congress of Obstetricians and Gynecologists; ADA = American Diabetes Association; ADIPS = Australian Diabetes in Pregnancy Society; BMI = body mass
index; CC = Carpenter-Coustan; CHT = chronic hypertension; d(s) = day(s); dL = deciliter; DM = diabetes mellitus; Dx = diagnosis/diagnostic; FPG = fasting plasma glucose; OGCT
= oral glucose tolerance test; GDM = gestational diabetes mellitus; GLT = glucose load test; g = grams; HAPO = Hyperglycemia and Adverse Pregnancy Outcomes Study; h = hour;
IADPSG = International Association of Diabetes and Pregnancy Study Groups; IFG = impaired fasting glucose; IGT = impaired glucose tolerance; IGT-2 = double impaired glucose
tolerance; IQR = inter-quartile range; JSOG = Japan Society of Obstetrics and Gynecology; kg = kilogram; LGA = large for gestational age; m = meter; mg = milligrams; NDDG =
National Diabetes Data Group; NR = not reported; OGTT = oral glucose tolerance test; PP= postpartum; PCS = prospective cohort study; PROM = premature rupture of the
membranes; RCS = retrospective cohort study; SD = standard deviation; SGA = small for gestational age; Tx = treatment; wk(s) = week(s); WHO = World Health Organization;
yr(s) = year(s)
Table D4. Characteristics of studies examining treatment outcomes of mothers and offspring, Key Questions 4 and 5
Author,
year
Study
Design
Dates of
study
Women Enrolled, n
Maternal Age, mean± SD (yr)
BMI, mean ± SD; median IQR
s
(kg/m )
Screening and Diagnostic
Tests
Interventions
Outcomes
Reported
Quality
Glucose Levels, mean ± SD
Country
Adams,
Inclusion/
Exclusion Criteria
Race
389
Inclusion: Positive
Screen: 50 g GCT (24–30
D-37
G1: Diet with weekly
Weight gain,
NOS = 9
Author,
year
Study
Design
Dates of
study
Women Enrolled, n
Maternal Age, mean± SD (yr)
BMI, mean ± SD; median IQR
s
(kg/m )
US
Interventions
Outcomes
Reported
Quality
Race
1998
Jan 1986 to
Sep 1996
Screening and Diagnostic
Tests
Glucose Levels, mean ± SD
Country
RCS
Inclusion/
Exclusion Criteria
G1: 31.5 ± 4.6
G2: 31.4 ± 4.9
G3: 30.2 ± 4.7
G1: 30.3 ± 7.2
G2: 26.1 ± 6.1
G3: 26.6 ± 7.5
NR
G1: White: 73
G2: White: 277
G3: White: 15
OGCT; meets NDDG
criteria (2 plasma
glucose values on
OGTT) for GDM
Exclusion: Multiple
gestation; fetal
congenital anomalies;
delivery before 34 wks;
delivery elsewhere;
diet or insulin therapy
initiated < 4 wks before
delivery
wks with 1-h cutoff by
NDDG criteria, ≥ 140
mg/dL)
Diagnostic:100 g OGTT at
24–30 wks (Fasting: 105
mg/dL;1 h 190 mg/dL; 2 h
165 mg/dL; 3 h 145 mg/dL)
blood glucose
monitoring, daily BG
self-monitoring and
insulin required
(n=76)
G2: Diet with weekly
blood glucose
monitoring (n=297)
G3: No treatment
(n=16)
D-38
shoulder
dystocia,
hypoglycemia,
stillbirth or
neonatal death,
birth trauma,
birth weight,
bone
fracture/clavicul
ar fracture,
nerve
palsy/brachial
plexus injury,
LGA, rectal
injury, neonatal
complications,
Horner's
syndrome,
hemidiaphragm
paralysis,
unilateral eyelid
ptosis from
partial cranial
nerve palsy
(good)
Author,
year
Study
Design
Dates of
study
Women Enrolled, n
Maternal Age, mean± SD (yr)
BMI, mean ± SD; median IQR
s
(kg/m )
Screening and Diagnostic
Tests
Interventions
Outcomes
Reported
G1: No diet, random
glucose checks, and
usual care (n=48)
Preeclampsia,
shoulder
dystocia, birth
weight, APGAR,
abnormal fetal
heart rate, SGA
Quality
Glucose Levels, mean ± SD
Country
Bevier,
1999
Inclusion/
Exclusion Criteria
Race
83
RCT
G1: 26.3 ± 6.0
G2: 27.4 ± 5.4
NR
NR
US
NR
G1: White: 2
Black: 1
Hispanic: 45
G2: White: 2
Black: 0
Hispanic: 33
Inclusion: Positive
OGCT screen and
negative OGTT
Exclusion:
Hypertension; collagen
disease; chronic renal
disease; cardiac or
pulmonary disease; Rh
sensitization; Hx of
preterm labor or SGA
Screen: 50 g GCT (24–30
wks with 1-h cutoff by
NDDG criteria, ≥ 140
mg/dL)
Diagnostic: 100 g OGTT
(24–30 wks with fasting:
105 mg/dL; 1 h 190 mg/dL;
2 h 165 mg/dL; 3 h 145
mg/dL)
HbA1c (28–32 wks)
D-39
G2: Standard
euglycemic diet,
HBGM, random
glucose checks
HBGM recorded in a
diary and reviewed
weekly; 3 meals and
3 snacks: 40%
carbohydrates, 20%
protein, and 40% fat
(n=35)
RoB =
Unclear
(fair)
Author,
year
Study
Design
Dates of
study
Women Enrolled, n
Maternal Age, mean± SD (yr)
BMI, mean ± SD; median IQR
s
(kg/m )
Screening and Diagnostic
Tests
Inclusion: Screened at
diabetic centre; Dx of
mild degree of glucose
intolerance; OGCT
>140 mg/dL and OAV
on OGTT
Screen: 50 g GCT (14–16
wks for at risk and 24–28
wks for women without risk
with 1 h cutoff) by CC and
NDDG criteria
Outcomes
Reported
Quality
G1: Elevated OGCT
and Normal OGTT
with no treatment
from 1989 to 1993;
from 1994 on
patients given dietary
advice; 25-30 kcal/kg
per day diet; biweekly visits, BG
monitoring (n=49)
Caesarean
delivery, birth
weight, APGAR,
LGA
NOS = 8
(good)
Race
112
RCS
G1: 30.6 ± 3.4
G2: 30.7 ± 4.8
1989 to
1995
G1: 23.12 ± 4.4
G2: 25.0 ± 5.7
Exclusion: NR
Italy
Interventions
Glucose Levels, mean ± SD
Country
Bonomo,
1997
Inclusion/
Exclusion Criteria
NR
G1: NR
G2: NR
Diagnostic: 100 g OGTT
(14–16 wks for at risk and
24–28 wks for women
without risk with Fasting, 1
h, 2 h, and 3 h intervals)
by CC and NDDG criteria
D-40
G2: 1 elevated OGTT
with no treatment
from 1989 to 1993;
from 1994 on
patients given dietary
advice; 25-30 kcal/kg
per day diet; biweekly visits, BG
monitoring (n=63)
Author,
year
Study
Design
Dates of
study
Women Enrolled, n
Maternal Age, mean± SD (yr)
BMI, mean ± SD; median IQR
s
(kg/m )
Screening and Diagnostic
Tests
Interventions
Outcomes
Reported
G1: Diet and regular
glucose monitoring;
dietary counseling;
24–30 kcal/kg per
day formal diet;
caloric intake divided
into 3 meals and 2–3
snacks; distributed as
50–55%
carbohydrates, 25–
30% protein, and
25% fat (n=150)
Caesarean
delivery, weight
gain,
hypoglycemia,
hyperbilirubine
mia, admission
to NICU, birth
weight, weight,
length, APGAR,
LGA, ponderal
index, SGA
Quality
Glucose Levels, mean ± SD
Country
Bonomo,
2005
Inclusion/
Exclusion Criteria
Race
300
RCT
G1: 31.1 ± 4.7
G2: 30.7 ± 5.1
1997 to
2002
G1: 23.1 ± 4.4
G2: 23.0 ± 4.5
Italy
G1: fasting 4.68 ± 0.45 mmol/L
G2: fasting 4.77 ± 0.52 mmol/L
Inclusion: Caucasian;
OGCT >140 mg/dL and
normal OGTT;
singleton pregnancies
Exclusion: Normal GCT;
one abnormal OGTT
value; GDM under CC
criteria
Screen: 50 g GCT (24–28
wks with 1 h cutoff by
Italian Society of
Diabetology criteria,
plasma glucose 1 h after
challenge ≥ 7.8 mmol/L)
Diagnostic:100 g OGTT
(within 7 d of GCT)
assessed by CC criteria
GCT/OGTT repeated at 30–
34 wks for complete
diagnosis of Borderline
Gestational Glucose
Intolerance (BGGI)
D-41
G2: No special care,
diet or treatment
(n=150)
RoB =
Unclear
(fair)
Author,
year
Study
Design
Dates of
study
Women Enrolled, n
Maternal Age, mean± SD (yr)
BMI, mean ± SD; median IQR
s
(kg/m )
Screening and Diagnostic
Tests
Interventions
Outcomes
Reported
Quality
G1: Consultation
with a dietitian; 2 weeks
of diet restriction;
fasting
glucose level
>105mg/dL, patient
referred to
endocrinologist,
received glucose
monitoring
device, and began
insulin treatment
(n=489)
Maternal
hypertension,
cesarean
delivery,
maternal birth
trauma
(postpartum
hemorrhage),
macrosomia,
shoulder
dystocia,
mortality
(intrauterine
fetal demise),
preterm labour,
APGAR scores
NOS = 7
(good)
Glucose Levels, mean ± SD
Country
Race
Chou, 2010
10,990
RCS (1)
G1: 34.4 ± NR
G2: 33.4 ± NR
Jan 2001 to
Sep 2008
Inclusion/
Exclusion Criteria
G1: 23.11 ± NR
G2: 23.45 ± NR
Taiwan
NR
Inclusion: Singleton
pregnancies delivered
at Cathay General
Hospital
Exclusion: Multiple
pregnancies, fetal
anomalies diagnosed
prenatally
Screen:
1 h, 50 g OGCT
Diagnostic:
3 h, 100 g OGTT (CC,
1982; NDDG, 1979)
NR
G2: Did not receive
further medical control
(n=385)
D-42
Author,
year
Study
Design
Dates of
study
Women Enrolled, n
Maternal Age, mean± SD (yr)
BMI, mean ± SD; median IQR
s
(kg/m )
RCT, multicenter
Sept 1993
to June
2003
Australia
Screening and Diagnostic
Tests
Inclusion: Singleton or
twin pregnancy; 16–30
wks gestation; prenatal
clinic attendance; ≥1
risk factors for GDM on
selective screen
(WHO) or positive 50 g
GCT and 75 g OGTT at
24–34 wks
Screen: 50 g GCT (24–34
wks with 1h cutoff by WHO
criteria, 1985) From 1998
onward any glucose level
above normal classified as
GDM (glucose level 1 h
after GCT of at least 7.8
mmol/L)
Interventions
Outcomes
Reported
G1: Ongoing care;
dietary advice; blood
glucose monitoring;
pre-prandial blood
glucose target 5.5
mmol/L; 2 h 7.0
mmol/L; BG target of
under 8.0 mmol/l was
set at more than 35
weeks of pregnancy
(n=490)
Induction of labor,
caesarean
delivery
(elective &
emergency),
shoulder
dystocia,
hypoglycemia,
hyperbilirubine
mia, stillbirth or
neonatal death,
admission to
NICU, birth
weight, bone
fracture/clavicul
ar fracture,
nerve
palsy/brachial
plexus injury,
“Any serious
prenatal
complication”,
APGAR, LGA +
SGA, 6 wk + 3
mo. Postpartum
physical
functioning,
general health,
vitality,
emotional role,
health state
utility, anxiety,
visits with
healthcare
professionals
Quality
Glucose Levels, mean ± SD
Country
Crowther,
2005
Gillman,
2010 (4-5
year
outcomes
for children)
Moss, 2007
(economic
analysis)
Inclusion/
Exclusion Criteria
Race
1,000
G1: 30.9 ± 5.4
G2: 30.1 ± 5.5
G1: 26.8 (23.3–31.2)
G2: 26.0 (22.9–30.9)
G1: 4.8 ± 0.7 mmol/L
G2: 4.8 ± 0.6 mmol/L
G1: White: 356 Asian: 92
Other: 42
G2: White: 396
Asian: 72
Other: 42
Exclusion: More severe
glucose impairment; Hx
of GDM; active chronic
systemic disease
Diagnostic: 75 g OGTT
(24–34 wks at fasting and
2-h) assessed by WHO
criteria, 1985 From 1998
onward any glucose level
above normal classified as
GDM (venous plasma
glucose level less than 6.1
– 7.0 mmol/L after
overnight fast and 7.0–
11.0 mmol/L at 2 h)
D-43
G2: Replicated routine
clinical care where
GDM screening not
available (n=510)
RoB =
Low
(good)
Author,
year
Study
Design
Dates of
study
Women Enrolled, n
Maternal Age, mean± SD (yr)
BMI, mean ± SD; median IQR
s
(kg/m )
Cohort (with
historical
controls)
Jan 2001 to
June 2006
US
Screening and Diagnostic
Tests
Interventions
Outcomes
Reported
Quality
Caesarean
delivery,
unplanned
caesarean
delivery, weight
gain, shoulder
dystocia,
admission to
NICU, birth
weight, neonatal
metabolic
complications,
APGAR
NOS = 7
(good)
Glucose Levels, mean ± SD
Country
Fassett,
2007
Inclusion/
Exclusion Criteria
Race
126
G1: 28.5 ± 5.8
G2: 29.2 ± 5.0
NR
NR
G1: White: 23
Black: 2
Hispanic: 39
Asian: 5
Other: 0
G2: White: 14
Black: 1
Hispanic: 35
Asian: 6
Other: 1
Inclusion: Women with
≥1 risk factors: prior
GDM; prior
macrosomia; firstdegree relative with
DM; prior stillbirth; prior
malformation; 24–28
wks gestation; GDM Dx
with CC criteria but not
NDDG
Screen: 50 g GCT (24–28
wks with 1 h cutoff)
Diagnostic: 100 g OGTT
(24–28 wks at Fasting, 1 h,
2 h, and 3 h intervals)
assessed by CC criteria
G1: Routine medical
nutrition therapy by
dietitian; formal diet
(20–35 kcal/kg of
prepregnancy body
weight); BG daily
self-monitoring,
insulin as needed
(n=69)
G2: Historical controls
before institution of
routine medical
nutrition therapy
(n=57)
Exclusion: NR
D-44
Author,
year
Study
Design
Dates of
study
Women Enrolled, n
Maternal Age, mean± SD (yr)
BMI, mean ± SD; median IQR
s
(kg/m )
Interventions
Outcomes
Reported
G1: Strict glycemic
control and tertiary
level obstetric
monitoring; dietary
counseling, calorierestricted diet, BG
daily self-monitoring,
insulin as needed
(n=149)
Caesarean
delivery, weight
gain,
hypoglycemia,
hyperbilirubine
mia, birth
trauma, birth
weight, child
outcomes 7-11
yrs Normal 2 h
GTT, at risk for
overweight
Quality
Race
300
G1: 30.7 ± 4.8
G2: 30.7 ± 4.6
Inclusion: Women with
GDM diagnosed
between 24–32 wks
gestation; low-risk
pregnancy
NR
RCT
Sept 1991
to May 1994
Screening and Diagnostic
Tests
Glucose Levels, mean ± SD
Country
Garner,
1997
Malcolm,
2006 (7-11
yr f-up)
Inclusion/
Exclusion Criteria
G1: 180.0 ± 25.2
(10.0 ± 1.4 mmol/L)
G2: 183.6 ± 32.4 mg/dL (10.2 ±
1.8 mmol/L)
Canada
G1: NR
G2: NR
Exclusion: Multiple
gestation; maternalfetal group
incompatibility; known
congenital anomaly;
prior evidence of
placenta previa or
abruptio placentae;
CHT; connective tissue
disease; endocrine
disorders; chronic
hepatic disease; longterm medical therapy
affecting glucose
metabolism; imminent
delivery
Screen: 75 g GCT (24–28
wks with 1 h cutoff by
O’Sullivan criteria,1 h level
of 144 mg/dL
Diagnostic: 75 g OGTT
(24–28 wks with Fasting
≥140 mg/dL, ≥11.1; 1 h, 2
h, and 3 h intervals)
assessed by Hatem et al.
criteria
D-45
G2: Routine obstetric
care (unrestricted
healthy diet) (n=150)
RoB =
High
(poor)
Author,
year
Study
Design
Dates of
study
Women Enrolled, n
Maternal Age, mean± SD (yr)
BMI, mean ± SD; median IQR
s
(kg/m )
RCT, multicenter
Oct 2002 to
Nov 2007
US
Screening and Diagnostic
Tests
Interventions
Outcomes
Reported
G1: Nutritional
counseling and
dietary therapy; daily
BG self-monitoring;
insulin as needed
(n=485)
Induction of labor,
caesarean
delivery,
preeclampsia,
GHT, BMI at
delivery, weight
gain, shoulder
dystocia,
hypoglycemia,
hyperbilirubine
mia, elevated
cord-blood cpeptide level,
stillbirth or
neonatal death,
birth trauma,
preterm
delivery,
admission to
NICU, primary
perinatal
outcome,
intravenous
glucose Tx,
respiratory
distress
syndrome, LGA,
SGA, BMI at
delivery
Quality
Glucose Levels, mean ± SD
Country
Landon,
2009
Inclusion/
Exclusion Criteria
Race
958
G1: 29.2 ± 5.7
G2: 28.9 ± 5.6
G1: 30.1 ± 5.0
G2: 30.2 ± 5.1
G1: fasting 86.6 ± 5.7 mg/dL
(4.8 ± 0.3 mmol/L); 1 h 191.8 ±
21.9 mg/dL (10.7 ± 1.2
mmol/L); 2 h 173.7 ± 21.8
mg/dL (9.6 ±1.2 mmol/L); 3 h
137.3 ± 29.0 mg/dL (7.6 ±1.6
mmol/L)
G2: fasting 86.3 ± 5.7 mg/dL
(4.8 ± 0.3 mmol/L); 1 h 193.4 ±
19.3 mg/dL (10.7 ± 1.1 mmol/L
); 2 h173.3 ± 19.6 mg/dL (9.6 ±
1.1 mmol/L ); 3 h 134.1 ± 31.5
G1:White: 123
Black: 56
Hispanic: 281
Asian: 22
Other: 3
G2: White: 119
Black: 54
Hispanic: 265
Asian: 28
Other: 7
Inclusion: Women
between 24 wks 0 days
and 30 wks 6 days;
OGCT values between
135 and 200 mg/dL or
7.5 and 11.1 mmol/L;
OGTT fasting glucose
<95 mg/dL and 2-3
timed measurements
exceeded above
thresholds at 1, 2, and
3 h.
Screen: 50 g GCT (1-h
cutoff)
Diagnostic: 100 g OGTT
(Fasting, 1 h, 2 h, and 3 h
intervals) assessed by the
th
4 IWC criteria (1 h 180
mg/dL; 2 h 155 mg/dL; 3 h
140 mg/dL)
Exclusion: Abnormal
result before 24 wks of
gestation; preexisting
diabetes; prior GDM;
Hx of stillbirth;
multifetal gestation;
asthma; CHT;
corticosteroid use;
known fetal anomaly;
likely preterm delivery
D-46
G2: Usual perinatal
care (n=473)
RoB =
Unclear
(fair)
Author,
year
Study
Design
Dates of
study
Women Enrolled, n
Maternal Age, mean± SD (yr)
BMI, mean ± SD; median IQR
s
(kg/m )
Screening and Diagnostic
Tests
Inclusion: Singleton
pregnancies; FPG <
140 mg/dL on OGTT;
CASE CONTROL:
GDM diagnosed > 37
wks; treated GDM and
diabetic matched 2:1
obesity, parity,
ethnicity, GA at
delivery (within 5 days),
and yr of delivery
Screen: 50 g GCT (1 h >37
wks for G2; G1 underwent
universal screening);
Plasma glucose < 130
mg/dL
Interventions
Outcomes
Reported
Quality
G1: Diet alone or
insulin and diet;
formal diet with
caloric restriction: 25
(overweight/obese) to
35 (normal weight)
kcal/kg for actual
pregnancy weight; 3
meals and 4 snacks;
daily BG selfmonitoring, insulin
therapy if diet not
successful in
achieving glycemic
control after 2 weeks
(n=1,110)
Induction of labor,
caesarean
delivery,
shoulder
dystocia,
hypoglycemia,
stillbirth or
neonatal death,
birth weight,
ponderal index,
arterial cord
<7.0, composite
outcome,
overall
metabolic
complications,
erythrocytosis,
respiratory
complication,
LGA, SGA
NOS = 9
(good)
Glucose Levels, mean ± SD
Country
Langer
2005
Inclusion/
Exclusion Criteria
Race
2,775
Cohort
G1: 29.1 ± 6
G2: 27.6 ± 6
Jan 1990 to
Sept 1999
G1: NR
G2: NR
US
G1: fasting 97 ± 16 mg/dL (5.4
mmol/L); 1 h 199 ± 28 mg/dL
(11.1 mmol/L); 2 h 178 ± 30
(9.9 mmol/L);
3 h 136 ± 36 (7.5 mmol/L)
G2: fasting 97 ± 15 mg/dL (5.4
mmol/L); 1 hr 199 ± 27 mg/dL
(11.1 mmol/L); 2 hr 181 ± 36
mg/dL (10.1 mmol/L); 3 hr 141
± 32 mg/dL 7.8 mmol/L)
Diagnostic: 100 g OGTT
(>37 wks for G2; G1
underwent universal
screening; Fasting, 1 h, 2
h, and 3 h intervals)
assessed by CC criteria
Exclusion:
Pregestational DM;
substance abusers;
multifetal gestation;
fetal anomalies
G2: Standard care until
delivery (n=555)
G1: White: 144
Black: 56
Hispanic: 910
G2: White: 61
Black: 17 Hispanic: 477
D-47
Author,
year
Study
Design
Dates of
study
Women Enrolled, n
Maternal Age, mean± SD (yr)
BMI, mean ± SD; median IQR
s
(kg/m )
Screening and Diagnostic
Tests
Interventions
Outcomes
Reported
Quality
Preeclampsia,
cesarean
delivery,
macrosomia,
hypoglycemia,
hyperbilirubine
mia
(phototherapy),
fetal trauma,
congenital
anomalies,
respiratory
distress
syndrome,
maternal/fetal
length of stay
NOS = 9
(good)
Glucose Levels, mean ± SD
Country
Naylor,
1997
Inclusion/
Exclusion Criteria
Race
3,778
RCT
G1: 32.7(4.3)
G2: 32.1 (4.4)
Sept 1989
to Mar 1992
G1: 24.2 (4.8)
G2: 24.7(5.8)
Inclusion: >24 yrs at
time of delivery, no Hx
of DM examined by
physician before 24
wks gestation, delivery
>28 wks ;
Screen: 50 g GCT (1 h
- Plasma glucose < 130
mg/dL
G1: Known to have
received treatment
for GDM (n= 143)
Diagnostic: 100 g OGTT
assessed by NDDG
criteria
G2: Usual perinatal
care (n= 115)
Exclusion: NR
Canada
NR
G1: White: 63
Black: 8
Asian: 27
Other: 45
G2: White: 67
Black: 2
Asian: 17
Other: 29
* ADA = American Diabetes Association; ADIPS = Australian Diabetes in Pregnancy Society; BMI = body mass index; CHT = chronic hypertension; d(s) = day(s); dL = deciliter;
DM = diabetes mellitus; Dx = diagnosis/diagnostic; FPG = fasting plasma glucose; GCT = glucose tolerance test; GDM = gestational diabetes mellitus; GLT = glucose load test; g =
grams; h = hour; IADPSG = International Association of Diabetes and Pregnancy Study Groups; JSOG = Japan Society of Obstetrics and Gynecology; mg = milligrams; NDDG =
National Diabetes Data Group; NR = not reported; NOS = Newcastle-Ottawa Quality Assessment Scale; n = number; OGTT = oral glucose tolerance test; PP= postpartum; PCS =
prospective cohort study; RCS = retrospective cohort study; RoB = Collaboration’s tool for assessing risk of bias; SD = standard deviation; tx = treatment; wk(s) = week(s); WHO =
World Health Organization; yr(s) = year(s)
D-48
Appendix E. List of Excluded Studies and Unobtained
Studies
Excluded – Comparator (N=227)
11. Reece EA, Hagay Z, Gay LJ, et al. A randomized
clinical trial of a fiber-enriched diabetic diet vs. the
standard American Diabetes Associationrecommended diet in the management of diabetes
mellitus in pregnancy. J Matern Fetal Invest
1995;5(1):8-12.
1. Catalano PM, Avallone DA, Drago NM, et al.
Reproducibility of the oral glucose tolerance test in
pregnant women. Am J Obstet Gynecol
1993;169(4):874-81.
2. Schrader HM, Jovanovic-Peterson L, Bevier WC, et
al. Fasting plasma glucose and glycosylated plasma
protein at 24 to 28 weeks of gestation predict
macrosomia in the general obstetric population. Am
J Perinatol 1995;12(4):247-51.
12. Hughes PF, Agarwal M, Newman P, et al. An
evaluation of fructosamine estimation in screening
for gestational diabetes mellitus. Diabet Med
1995;12(8):708-12.
3. Moses RG, Griffiths RD. Can a diagnosis of
gestational diabetes be an advantage to the outcome
of pregnancy? J Soc Gynecol Investig
1995;2(3):523-5.
13. Agardh CD, Aberg A, Norden NE. Glucose levels
and insulin secretion during a 75 g glucose
challenge test in normal pregnancy. J Intern Med
1996;240(5):303-9.
4. Bassaw B, Ataullah I, Roopnarinesingh S, et al.
Diabetes in pregnancy. Int J Gynaecol Obstet
1995;50(1):5-9.
14. Hod M, Rabinerson D, Kaplan B, et al. Perinatal
complications following gestational diabetes
mellitus how 'sweet' is ill? Acta Obstet Gynecol
Scand 1996;75(9):809-15.
5. de VM, Major CA, Morgan MA, et al. Postprandial
versus preprandial blood glucose monitoring in
women with gestational diabetes mellitus requiring
insulin therapy. N Engl J Med 1995;333(19):123741.
15. Nasrat HA, Ardawi MS, Abalkhail BA. The
diagnosis of "pathological hyperglycaemia' in
gestational diabetes in a high risk obstetric
population. Diabetic Med 1996;13(10):861-7.
6. Damm P, Kuhl C, Hornnes P, et al. A longitudinal
study of plasma insulin and glucagon in women
with previous gestational diabetes. Diabetes Care
1995;18(5):654-65.
16. Di SN, Ronsisvalle E, Fulghesu AM, et al. Insulin
plasma levels in pregnant patients with impaired
glucose tolerance: relationship with pregnancy
outcome. Gynecol Obstet Invest 1996;42(1):16-20.
7. Koukkou E, Taub N, Jackson P, et al. Difference in
prevalence of gestational diabetes and perinatal
outcome in an innercity multiethnic London
population. Eur J Obstet Gynecol Reprod Biol
1995;59(2):153-7.
17. Tranquilli AL, Pizzichini L, Cingolani F, et al.
Prediction of the need for insulin therapy in
pregnant women with impaired gestational glucose
tolerance (IGGT). Clin Exp Obstet Gynecol
1996;23(2):79-82.
8. Gribble RK, Meier PR, Berg RL. Blood glucose
limits in the diagnosis of impaired glucose tolerance
during pregnancy. Relation to morbidity. Obstet
Gynecol 1995;86(3):405-10.
18. Moses RG. The recurrence rate of gestational
diabetes in subsequent pregnancies. Diabetes Care
1996;19(12):1348-50.
19. Di CG, Benzi L, Casadidio I, et al. Screening of
gestational diabetes in Tuscany: results in 2000
cases. Ann Ist Super Sanita 1997;33(3):389-91.
9. al-Najashi SS. Control of gestational diabetes. Int J
Gynaecol Obstet 1995;49(2):131-5.
10. Kjos SL, Peters RK, Xiang A, et al. Predicting
future diabetes in Latino women with gestational
diabetes. Utility of early postpartum glucose
tolerance testing. Diabetes 1995;44(5):586-91.
20. Fedele D, Lapolla A. A protocol of screening of
gestational diabetes mellitus. Ann Ist Super Sanita
1997;33(3):383-7.
E-1
21. Bienstock JL, Blakemore KJ, Wang E, et al.
Managed care does not lower costs but may result
in poorer outcomes for patients with gestational
diabetes. Am J Obstet Gynecol 1997;177(5):1035-7.
controlled gestational diabetes. Obstet Gynecol
1998;91(4):600-4.
34. Lao TT, Lee CP. Gestational 'impaired glucose
tolerance': should the cut-off be raised to 9 mmol l(1)? Diabetic Med 1998;15(1):25-9.
22. Helton MR, Arndt J, Kebede M, et al. Do low-risk
prenatal patients really need a screening glucose
challenge test? J Fam Pract 1997;44(6):556-61.
35. Moses RG, Moses J, Davis WS. Gestational
diabetes: Do lean young Caucasian women need to
be tested? Diabetes Care 1998;21(11):1803-6.
23. Avery MD, Leon AS, Kopher RA. Effects of a
partially home-based exercise program for women
with gestational diabetes. Obstet Gynecol
1997;89(1):10-5.
36. Moses RG, Moses M, Russell KG, et al. The 75-g
glucose tolerance test in pregnancy - A reference
range determined on a low-risk population and
related to selected pregnancy outcomes. Diabetes
Care 1998;21(11):1807-11.
24. al-Najashi SS. Diagnosis of gestational diabetes
mellitus. A study of 315 pregnant women at King
Fahd Hospital of the University, Al-Khobar, Saudi
Arabia. Bahrain Med Bull 1997;19(4):104-7.
37. Lemen PM, Wigton TR, Miller-McCarthey AJ, et
al. Screening for gestational diabetes mellitus in
adolescent pregnancies. Am J Obstet Gynecol
1998;178(6):1251-4.
25. Persson B, Edwall L, Hanson U, et al. Insulin
sensitivity and insulin response in women with
gestational diabetes mellitus. Horm Metab Res
1997;29(8):393-7.
26. Berria R, Murgia C, Serri F, Pilia I. GDM:
screening, diagnosis and management. 1997.
38. Lauszus FF, Paludan J, Klebe JG. Birthweight in
women with potential gestational diabetes mellitus An effect of obesity rather than glucose intolerance?
Acta Obstet Gynecol Scand 1999;78(6):520-5.
27. Casey BM, Lucas MJ, McIntire DD, et al.
Pregnancy outcomes in women with gestational
diabetes compared with the general obstetric
population. Obstet Gynecol 1997;90(6):869-73.
39. Roncaglia N, Bellini P, Arreghini A, et al.
Gestational diabetes mellitus: intensive versus mild
treatment. Clin Exp Obstet Gynecol 1999;26(2):957.
28. Lurie S, Levy R, Weiss R, et al. Low values on 50
gram glucose challenge test or oral 100 gram
glucose tolerance test are associated with good
perinatal outcome. J Obstet Gynaecol
1998;18(5):451-4.
40. McFarland MB, Langer O, Conway DL, et al.
Dietary therapy for gestational diabetes: how long is
long enough? Obstet Gynecol 1999;93(6):978-82.
41. Kvetny J, Poulsen HF, Damgaard DW. Results from
screening for gestational diabetes mellitus in a
Danish county. Dan Med Bull 1999;46(1):57-9.
29. Ramachandran A, Snehalatha C, Clementina M, et
al. Foetal outcome in gestational diabetes in south
Indians. Diabetes Res Clin Pract 1998;41(3):185-9.
42. Shivvers SA, Lucas MJ. Gestational diabetes - Is a
50-g screening result >= 200 mg/dL diagnostic? J
Reprod Med 1999;44(8):685-8.
30. Whitaker RC, Pepe MS, Seidel KD, et al.
Gestational diabetes and the risk of offspring
obesity. Pediatrics 1998;101(2):e9.
43. Jovanovic L, Gutierrez M, Peterson CM. Chromium
supplementation for women with gestational
diabetes mellitus. J Trace Elem Exp Med
1999;12(2):91-7.
31. Kitzmiller JL, Elixhauser A, Carr S, et al.
Assessment of costs and benefits of management of
gestational diabetes mellitus. Diabetes Care
1998;21(Suppl 2):B123-B130.
44. Vohr BR, McGarvey ST, Tucker R. Effects of
maternal gestational diabetes on offspring adiposity
at 4-7 years of age. Diabetes Care 1999;22(8):128491.
32. Schafer-Graf UM, Dupak J, Vogel M, et al.
Hyperinsulinism, neonatal obesity and placental
immaturity in infants born to women with one
abnormal glucose tolerance test value. J Perinat
Med 1998;26(1):27-36.
45. Mirghani OA, Saeed OK. A simplified management
of diabetic pregnant woman. Saudi Med J
2000;21(4):335-9.
33. Major CA, Henry MJ, de VM, et al. The effects of
carbohydrate restriction in patients with diet-
46. Rae A, Bond D, Evans S, et al. A randomised
controlled trial of dietary energy restriction in the
E-2
management of obese women with gestational
diabetes. Aust N Z J Obstet Gynaecol
2000;40(4):416-22.
58. MacNeill S, Dodds L, Hamilton DC, et al. Rates
and risk factors for recurrence of gestational
diabetes. Diabetes Care 2001;24(4):659-62.
47. Langer O, Conway DL, Berkus MD, et al. A
comparison of glyburide and insulin in women with
gestational diabetes mellitus. N Engl J Med
2000;343(16):1134-8.
59. Ray JG, Vermeulen MJ, Shapiro JL, et al. Maternal
and neonatal outcomes in pregestational and
gestational diabetes mellitus, and the influence of
maternal obesity and weight gain: the DEPOSIT
study. Diabetes Endocrine Pregnancy Outcome
Study in Toronto. QJM 2001;94(7):347-56.
48. Rudge MV, Calderon IM, Ramos MD, et al.
Perinatal outcome of pregnancies complicated by
diabetes and by maternal daily hyperglycemia not
related to diabetes. A retrospective 10-year analysis.
Gynecol Obstet Invest 2000;50(2):108-12.
60. Xiong X, Saunders LD, Wang FL, et al. Gestational
diabetes mellitus: prevalence, risk factors, maternal
and infant outcomes. Int J Gynaecol Obstet
2001;75(3):221-8.
49. Rigano S, Ferrazzi E, Radaelli T, et al. Sonographic
measurements of subcutaneous fetal fat in
pregnancies complicated by gestational diabetes and
in normal pregnancies. Croat Med J
2000;41(3):240-4.
61. Baliutaviciene D, Petrenko V, Zalinkevicius R.
Selective or universal diagnostic testing for
gestational diabetes mellitus. Int J Gynaecol Obstet
2002;78(3):207-11.
50. Bancroft K, Tuffnell DJ, Mason GC, et al. A
randomised controlled pilot study of the
management of gestational impaired glucose
tolerance. BJOG 2000;107(8):959-63.
62. Gezer A, Esen F, Mutlu H, et al. Prognosis of
patients with positive screening but negative
diagnostic test for gestational diabetes. Arch
Gynecol Obstet 2002;266(4):201-4.
51. Lao TT, Ho LF. Impaired glucose tolerance and
pregnancy outcome in Chinese women with high
body mass index. Hum Reprod 2000;15(8):1826-9.
63. Di CG, Volpe L, Casadidio I, et al. Universal
screening and intensive metabolic management of
gestational diabetes: cost-effectiveness in Italy.
Acta Diabetol 2002;39(2):69-73.
52. Simpson RW, Kast SJ. Management of gestational
diabetes with a conservative insulin protocol. The
Medical Journal Of Australia 2000;172(11):537-40.
64. Homko CJ, Sivan E, Reece EA. The impact of selfmonitoring of blood glucose on self-efficacy and
pregnancy outcomes in women with diet-controlled
gestational diabetes. Diabetes Educ 2002;28(3):43543.
53. Hearty RT, Traub AI, Hadden DR. Screening for
hyperglycaemia in pregnancy: analysis of two
screening protocols and review of current methods.
Ulster Med J 2000;69(1):35-43.
65. Rumbold AR, Crowther CA. Women's experiences
of being screened for gestational diabetes mellitus.
Aust N Z J Obstet Gynaecol 2002;42(2):131-7.
54. Crowe SM, Mastrobattista JM, Monga M. Oral
glucose tolerance test and the preparatory diet. Am
J Obstet Gynecol 2000;182(5):1052-4.
66. Pullen F, Grenfell A. The diagnosis of gestational
diabetes in a multiethnic population: Which
diagnostic criteria should be used with respect to
maternal outcome? Pract Diabetes Int
2002;29(9):279-82.
55. Wong L, Tan AS. The glucose challenge test for
screening gestational diabetes in pregnant women
with no risk factors. Singapore Med J
2001;42(11):517-21.
67. Pettitt DJ, Ospina P, Jovanovic L. Comparison of an
insulin analog, insulin aspart, and regular human
insulin with no insulin in gestational diabetes
mellitus. Diabetologia 2002;45(Suppl 2):A254A255.
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2010;89(5):700-4.
9. Sapienza AD, Francisco RP, Trindade TC, et al.
Factors predicting the need for insulin therapy in
patients with gestational diabetes mellitus. Diabetes
Res Clin Pract 2010;88(1):81-6.
6. Gonzalez-Quintero VH, Istwan NB, Rhea DJ, et al.
Antenatal factors predicting subsequent need for
insulin treatment in women with gestational
diabetes. J Womens Health 2008;17(7):1183-7.
10. Patel S, Fraser A, Davey SG, et al. Associations of
gestational diabetes, existing diabetes, and
glycosuria with offspring obesity and
cardiometabolic outcomes. Diabetes Care
2012;35(1):63-71.
7. Davenport MH, Mottola MF, McManus R, et al. A
walking intervention improves capillary glucose
control in women with gestational diabetes mellitus:
a pilot study. Appl Physiol Nutr Metab
2008;33(3):511-7.
11. Renar IP, Tomic M, Horvat B, Metelko Z.
Screening and intervention in getational diabetes
mellitus. Diabetologia 1997;40(suppl 1):848.
8. Son GH, Kwon JY, Kim YH, et al. Maternal serum
triglycerides as predictive factors for large-forgestational age newborns in women with gestational
Excluded – Unobtainable (N=7)
1. Bell AW. Insulin Resistance in Pregnancy:
Implications for Gestational Diabetes Source: In:
Nutrition Society of Australia; p. 11-19; The
Society; 1995 Series: Proceedings – Nutrition
Society of Australia. Number: Vol 19 ISSN: 03141004 Language: English. Melbourne, Australia.
7. Cheng YW, Block-Kurbisch I, Lydell J, Caughey
AB. 2008. (missing reference data)
8.
2. Mori M, Dolci M, Baccetti F. Evaluation after 1, 2,
3 years to delivery of glucose tolerance in women
with gestational diabetes and of sons' development
anthropometric. 1997.
3. Meyer WJ, Carbone J, Gauthier DW, et al. Early
gestational glucose screening and gestational
diabetes. J Reprod Med 1996;41(9):675-9.
4. Gorgojo Martinez JJ, Almodovar Ruiz F, Lopez
Hernandez E, et al. Incidence of gestational diabetes
mellitus according to different diagnostic criteria in
the southeast Madrid area. Influence of diagnosis on
materno-fetal parameters. Rev Clin Esp
2002;202(3):136-41.
5. Fan ZT, Yang HX, Gao XL, et al. Pregnancy
outcome in gestational diabetes. Int J Gynaecol
Obstet 2006;94(1):12-6.
6. Eslamian L, Ramezani Z. Breakfast as a screening
test for gestational diabetes. Int J Gynaecol Obstet
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E-22
Sultan M, Khlaif H. Impact of gestational impaired
glucose tolerance test (GIGTT) on pregnancy
outcome. Jamahiriya Med J 2010;10(4):268-71.
Appendix F. Key Question 1 – HSROC Curves
Hierarchical summary receiver-operator curves (HSROC) with the 95 percent confidence
ellipse are shown below for two different comparisons. The summary graphic compares the
sensitivity and specificity for all studies comparing a particular screening test with GDM
diagnostic criteria. All points are clustered in the upper left hand quadrant and there is no overalp
between the 95 percent confidence ellipse and the diagonal null line. This indicates that the
ability of the screening test to correctly classify patients with GDM is significantly better than
random classification.
Figure F-1. HSROC curve: 50 g OGCT (≥140 mg/dL and ≥130 mg/dL ) by Carpenter-Coustan criteria
F-1
Figure F-2. HSROC curve: 50 g OGCT (≥ 140 mg/dL) by NDDG criteria
F-2
Appendix G. Adjusted Analyses for KQ3
Tables G-1 and G-2, on the following pages, provide unadjusted and adjusted results for
maternal and offspring outcomes, respectively. The data that contributed to the meta-analysis
for each comparison and outcome are provided. The data used in the meta-analyses and reported
in the main report were unadjusted data from the relevant studies. We have also included the
following for each study: whether the study provided adjusted results; what the adjusted effect
estimate was (with its 95% confidence interval); whether the adjusted results were different
from the unadjusted results in terms of statistical significance; and the variables that were
controlled for in the adjusted analyses. For the overall pooled estimate within each comparison,
we have noted whether the estimate would have changed if the adjusted values were used rather
than the unadjusted values. For comparisons and outcomes with single studies, we have
indicated whether the unadjusted and adjusted estimates differed in terms of statistical
significance.
G-1
Table G-1. Maternal outcomes: Unadjusted data included in meta-analyses for Key Question 3 and adjusted effect estimates where
available from included studies
Author, Year
n/N*
PREECLAMPSIA
CC GDM vs. no GDM
Cheng, 2009
17/273
n/N*
627/
13,940
Weight
Effect estimate
†
(95% CI)
Were
there
adjusted
results?
Adjusted
effect
estimate
(95% CI)
Adjusted
results
different
52.5%
1.38 (0.87, 2.21)
yes
1.3 (0.71, 2.38)
no
yes
n/a
n/a
1.56 (0.58, 4.22) no
Naylor, 1996
Pennison, 2001
10/115
9/43
144/2,940 30.4%
10/69
17.2%
1.78 (0.96, 3.28)
1.44 (0.64, 3.27)
Total (95% CI)
431
16,949
1.50 (1.07, 2.11)
100.0%
no
264/3,117 86.8%
1.49 (1.14, 1.94)
yes
1.47 (1.02, 2.13) no
Naylor, 1996
Total (95% CI)
31/580
3,697
1.63 (0.82, 3.22)
1.51 (1.17, 1.93)
no
n/a
13.2%
100.0%
Impact of
adjusted results
on pooled
estimates
Parity, maternal age, race
or ethnicity, gestational
weight gain, gestational
age at delivery, year of
delivery, epidural
anesthesia, induction of
labor, (with mode of
delivery and episiotomy
additionally controlled for
perineal laceration,
postpartum hemorrhage,
shoulder dystocia, and
birth trauma)
African American race,
elevated BMI
Adding adjusted
values would not
change
significance
CC GDM vs. false-positive
Berggren, 2011 58/460
10/115
575
Variables in model
Parity, maternal delivery
age over 35 years,
ethnicity, delivery year;
cesarean and operative
deliveries were also
controlled for prior
cesarean.
Summary measure
is adjusted
prevalence ratio
n/a
Adding adjusted
values would not
change
significance
NDDG 1 abnormal OGTT vs. no GDM
G-2
Kim, 2002
5/122
18/577
Total (95% CI)
122
577
NDDG false-positive vs. no GDM
Biri, 2009
7/326
21/1,432
Stamilio, 2004
10/164
107/1,661
100.0%
100.0%
1.33 (0.48, 3.65)
1.33 (0.48, 3.65)
no
35.5%
64.5%
1.46 (0.63, 3.42)
0.95 (0.51, 1.77)
no
yes
Total (95% CI)
100.0%
1.10 (0.67, 1.83)
490
3,093
WHO IGT vs. no GDM
Jensen, 2003
16/289
158/2,596 50.3%
0.91 (0.55, 1.50)
Nord, 1995
Yang, 2002
Total (95% CI)
14/391
0/302
3,289
42.1%
7.6%
100.0%
13/223
3/102
614
MATERNAL HYPERTENSION
CC vs. no GDM
Chou, 2010
10/489
238/
10,116
Landon, 2011
62/455
31/423
n/a
n/a
No change
n/a
0.33 (0.1, 1.11)
n/a
no
Body mass index, parity,
gestational age at
delivery, chronic
hypertension, tobacco
use, race, midtrimester
serum -fetoprotein and
human chorionic
gonadotropin levels,
maternal age, and history
of preeclampsia in a prior
pregnancy.
Adding adjusted
values would not
change
significance
yes
0.9 (0.5,1.8)
no
1.63 (0.78, 3.40)
no
20.59 (1.07, 395.30) yes
1.47 (0.62, 3.52)
n/a
2.1 (0.89, 4.94)
n/a
yes
22.6%
0.87 (0.46, 1.63)
no
n/a
34.1%
1.86 (1.23, 2.80)
yes
1.94 (1.09, 3.52) no
Pre-pregnancy BMI,
maternal age,parity,
smoking, weight gain
during pregnancy,
gestational age,
anamnestic risk indicators
for GDM, ethnic
background and clinical
centre.
Adding adjusted
values would not
change
significance
G-3
n/a
Maternal age, gestational
age at enrollment and at
delivery, parity, BMI, and
race and ethnicity
Lapolla, 2011
Ricart, 2005
9/112
10/263
76/1,815 21.1%
108/6,350 22.2%
1.92 (0.99, 3.73)
2.24 (1.18, 4.22)
Total (95% CI)
1,319
18,704
1.64 (1.11, 2.42)
100.0%
no
yes
n/a
n/a
2.34 (1.15, 4.77) no
Maternal BMI, fetal sex
(male), gestational age,
maternal age,
macrosomia (yes), PIH
(yes)
Adding adjusted
values would not
change
significance
CC vs. false-positive
Berggren, 2011 33/460
150/3,117 77.6%
1.49 (1.04, 2.15)
yes
1.48 (1.02,2.13) no
Ricart, 2005
10/263
42/1,838
22.4%
1.66 (0.85, 3.28)
no
n/a
Total (95% CI)
723
4,955
100.0%
1.53 (1.11, 2.11)
108/6,350 100.0%
1.35 (0.94, 1.94)
yes
1.25 (0.83, 1.90) no
Maternal BMI, fetal sex
(male), gestational age,
maternal age,
macrosomia (yes), PIH
(yes)
76.9%
3.19 (1.86, 5.49)
yes
2.3 (1.23,4.6)
no
Age and BMI (adjusted
estimate for “hypertensive
disorders)
no
n/a
n/a
Parity, maternal delivery
age over 35 years,
ethnicity, delivery year;
cesarean and operative
deliveries were also
controlled for prior
cesarean.
Summary measure
is adjusted
prevalence ratio
n/a
Adding adjusted
values would not
change
significance
CC False-positive vs. no GDM
Ricart, 2005
42/
1,838
CC 1 abnormal vs. no GDM
Corrado, 2009
21/152
27/624
Vambergue,
2000
Total (95% CI)
14/131
5/108
23.1%
2.31 (0.86, 6.21)
283
732
100.0%
2.96 (1.84, 4.77)
Adding adjusted
values would not
change
significance
Adding adjusted
values would not
change
significance
IADPSG GDM vs. no GDM
G-4
Lapolla, 2011
9/112
76/1815 100.0%
IADPSG IGT (1 abnormal OGTT) vs no GDM
Black, 2010
36/391
490/7,020 100.0%
n/a
No change
1.92 (0.99, 3.73)
no
n/a
1.32 (0.96, 1.82)
yes
1.49 (1.03, 2.16) yes
Changed to
Adjusted for maternal
age, race/ethnicity, parity, statistically
significant
prepregnancy BMI,
gestational weight gain,
infant sex, and gestational
age at OGTT
IADPSG IFG vs. no GDM
Black, 2010
90/886
490/7,020 100.0%
1.46 (1.18, 1.80)
yes
1.29 (1.01, 1.66) no
No change
Adjusted for maternal
age, race/ethnicity, parity,
prepregnancy BMI,
gestational weight gain,
infant sex, and gestational
age at OGTT
IADPST IGT-2 vs. no GDM
Black, 2010
11/83
490/7,020 100.0%
1.90 (1.09, 3.31)
yes
2.33 (1.20, 4.51) no
No change
Adjusted for maternal
age, race/ethnicity, parity,
prepregnancy BMI,
gestational weight gain,
infant sex, and gestational
age at OGTT
IADPSG IGT IFG vs no GDM
Black, 2010
47/331
490/7,020 100.0%
2.03 (1.54, 2.69)
yes
2.01 (1.42, 2.84) no
No change
Adjusted for maternal
age, race/ethnicity, parity,
prepregnancy BMI,
gestational weight gain,
infant sex, and gestational
age at OGTT
IADPSG IGT vs IFG
Black, 2010
36/391
IADPSG IGT vs. IGT-2
Black, 2010
36/391
IADPSG IGT vs IGT IFG
90/886
100.0%
0.91 (0.63, 1.31)
no
n/a
n/a
No change
11/83
100.0%
0.69 (0.37, 1.31)
no
n/a
n/a
No change
Black, 2010
36/391
IADPSG IFG vs. IGT-2
47/331
100.0%
0.65 (0.43, 0.98)
no
n/a
n/a
No change
Black, 2010
90/886
IADPSG IFG vs IGT IFG
Black, 2010
90/886
IADPSG IGT-2 vs. IGT IFG
11/83
100.0%
0.77 (0.43, 1.37)
no
n/a
n/a
No change
47/331
100.0%
0.72 (0.51, 0.99)
no
n/a
n/a
No change
G-5
Black, 2010
11/83
WHO IGT vs. no GDM
Jensen, 2003
16/289
CESAREAN DELIVERY
CC GDM vs. no GDM
Cheng, 2009
62/
273
Chico, 2005
0.93 (0.51, 1.72)
no
n/a
n/a
No change
158/2,596 158
0.91 (0.55, 1.50)
yes
0.9 (0.5,1.8)
no
No change
pre-pregnancy BMI,
maternal age, parity,
smoking, weight gain
during pregnancy,
gestational age,
anamnestic risk indicators
for GDM, ethnic
background and clinical
centre.
2,356/
13,940
13.2%
1.34 (1.08, 1.68)
yes
1.44 (1.01,2.07) no
47/331
100.0%
1,442/
16.2%
5,767
3,761/
18.2%
10,116
158/1,110 13.9%
1.16 (0.99, 1.35)
no
n/a
n/a
1.08 (0.96, 1.20)
no
n/a
n/a
1.67 (1.36, 2.06)
no
n/a
n/a
Lapolla, 2011
Naylor, 1996
122/
422
196/
489
132/
555
49/112
34/115
564/1,815 13.3%
585/2,940 10.5%
1.41 (1.13, 1.76)
1.49 (1.11, 1.99)
no
yes
n/a
1.2 (0.7,2.0)
n/a
yes
Pennison, 2001
13/43
17/69
3.9%
1.23 (0.66, 2.27)
yes
1.52 (0.54, 4.31) no
Ricart, 2005
59/263
1,219/
6,350
11.3%
1.17 (0.93, 1.47)
yes
0.95 (0.67, 1.35) no
Ching-Yu, 2010
Langer, 2005
G-6
Parity, maternal age, race
or ethnicity, gestational
weight gain, gestational
age at delivery, year of
delivery, epidural
anesthesia, induction of
labor, (with mode of
delivery and episiotomy
additionally controlled for
perineal laceration,
postpartum hemorrhage,
shoulder dystocia, and
birth trauma)
Maternal age. race. parity.
BMI, history of
preeclampsia, history of
cesarean delivery.
gestational age. and
current preeclampsia
African American race,
elevated BMI
Maternal BMI, fetal sex
(male), gestational age,
maternal age,
macrosomia (yes), PIH
(yes)
Schwartz, 1999
38/154
Total (95% CI)
2,426
1,110/
7,207
49,314
10.8%
1.60 (1.21, 2.12)
100.0%
1.32 (1.17, 1.48)
no
n/a
n/a
Adding adjusted
results would
likely reduce
lower confidence
interval closer to
null; not sure
whether
significance
would change
CC GDM vs. false-positive
Berggren, 2011 160/
460
942/3,117 72.3%
1.15 (1.00, 1.32)
yes
1.16 (1.04, 1.30) yes
Naylor, 1996
Ricart, 2005
34/115
59/263
136/580 13.2%
393/1,838 0.187%
1.26 (0.92, 1.73)
1.05 (0.82, 1.34)
no
no
n/a
n/a
n/a
n/a
Schwartz, 1999
Total (95% CI)
38/154
992
197/1,066 14.5%
6,601
100.0%
1.34 (0.99, 1.81)
1.16 (1.05, 1.29)
no
n/a
n/a
Parity, maternal delivery
age over 35 years,
ethnicity, delivery year;
cesarean and operative
deliveries were also
controlled for prior
cesarean.
Adding adjusted
values would not
change
significance
CC GDM vs. 1 abnormal OGTT
Chico, 2005
122/
19/59
422
CC 1 abnormal OGTT vs. no GDM
100.0%
0.90 (0.60, 1.34)
no
n/a
n/a
Chico, 2005
19/59
15.5%
1.29 (0.89, 1.87)
no
n/a
n/a
Corrado, 2009
Rust, 1996
Vambergue,
2000
Total (95% CI)
85/152
14/78
23/131
1,442/
5,767
243/624
32/205
11/108
73.1%
6.6%
4.8%
1.44 (1.21, 1.71)
1.15 (0.65, 2.04)
1.72 (0.88, 3.37)
yes
no
no
2.2 (1.55, 3.39)
n/a
n/a
no
n/a
n/a
420
6,704
100.0%
1.40 (1.21, 1.63)
No change
Age and BMI
Adding adjusted
values would not
G-7
change
significance
CC false-positive vs. no GDM
Bo, 2004
103/
28/91
4.0%
315
Lapolla, 2007
45/128
100/334
5.8%
Naylor, 1996
136/
585/2,940 17.8%
580
1.06 (0.75, 1.50)
no
n/a
n/a
1.17 (0.88, 1.56)
1.18 (1.00, 1.39)
no
yes
n/a
1.2 (0.9, 1.5)
n/a
no
Ricart, 2005
393/
1,838
1,219/
6,350
46.9%
1.11 (1.01, 1.23)
yes
1.06 (0.91, 1.23) no
Schwartz, 1999
197/
1,066
3,927
1,110/
7,207
16,922
25.5%
1.20 (1.05, 1.38)
no
n/a
100.0%
1.15 (1.07, 1.23)
NDDG 1 Abnormal OGTT vs. no GDM
Kim, 2002
27/122
83/577
100.0%
CC 1 abnormal OGTT vs. false-positive
1.69 (1.04, 2.75)
Total (95% CI)
Kwik, 2007
46/156
61/197
Lapolla, 2007
27/48
45/128
Total (95% CI) 204
325
NDDG GDM vs no GDM
Adams, 1998
4/16
10/64
NDDG false-positive vs. no GDM
Ardawi, 2000
24/187
67/529
Hillier, 2007
208/326
785/1,432
Retnakaran,
44/128
23/74
2008
Maternal age. race. parity.
BMI, history of
preeclampsia, history of
cesarean delivery.
gestational age. and
current preeclampsia
Maternal BMI, fetal sex
(male), gestational age,
maternal age,
macrosomia (yes), PIH
(yes)
n/a
Adding adjusted
value may lower
the lower
confidence bound
closer to null; not
clear whether
significance
would change
no
n/a
n/a
n/a
n/a
n/a
n/a
50.7%
49.3%
100.0%
0.95 (0.69, 1.31)
1.60 (1.14, 2.25)
1.23 (0.73, 2.06)
no
no
100.0%
1.60 (0.58, 4.45)
no
n/a
n/a
3.9%
83.2%
4.3%
1.01 (0.66, 1.57)
1.16 (1.06, 1.28)
1.11 (0.73, 1.68)
no
no
no
n/a
n/a
n/a
n/a
n/a
n/a
No change
No change
G-8
No change
Stamilio, 2004
39/164
286/1,661 8.6%
1.38 (1.03, 1.85)
Total (95% CI)
805
3,696
1.17 (1.08, 1.28)
100.0%
yes
1.76 (0.99, 3.14) yes
Body mass index, parity,
gestational age at
delivery, chronic
hypertension, tobacco
use, race, midtrimester
serum -fetoprotein and
human chorionic
gonadotropin levels,
maternal age, and history
of preeclampsia in a prior
pregnancy.
Adding adjusted
values would not
change
significance
WHO IGT vs no GDM
Aberg, 2001
12/131
249/4,526 7.0%
1.67 (0.96, 2.89)
no
n/a
n/a
Jensen, 2003
54/289
450/2,596 26.4%
1.08 (0.84, 1.39)
yes
1 (0.7, 1.4)
no
Nord, 1995
Yang, 2002
38/223
75/102
45/391
199/302
12.7%
53.9%
1.48 (0.99, 2.21)
1.12 (0.97, 1.29)
no
no
n/a
n/a
n/a
n/a
Total (95% CI)
745
7,815
100.0%
1.18 (1.01, 1.37)
Lapolla, 2011
9/112
IADPSG IGT vs no GDM
76/1,815
100.0%
1.92 (0.99, 3.73)
no
n/a
n/a
No change
Black, 2010
1,112/
7,020
100.0%
1.11 (0.89, 1.39)
yes
1.03 (0.77,1.38) no
No change
Adjusted for maternal
age, race/ethnicity, parity,
prepregnancy BMI,
gestational weight gain,
infant sex, and gestational
age at OGTT
Pre-pregnancy body mass
index (BMI), maternal
age,parity, smoking,
weight gain during
pregnancy, gestational
age, anamnestic risk
indicators for GDM, ethnic
background and clinical
centre.
Adding adjusted
values would not
change
significance
IADPSG GDM vs no GDM
69/391
G-9
IADPSG IFG vs no GDM
1,112/
7,020
100.0%
1.28 (1.11, 1.47)
yes
1.16 (0.95,1.41) yes
Changed to not
Adjusted for maternal
age, race/ethnicity, parity, statistically
significant
prepregnancy BMI,
gestational weight gain,
infant sex, and gestational
age at OGTT
1,112/
7,020
100.0%
1.58 (0.94, 2.64)
yes
1.39 (0.78, 2.46) no
No change
Adjusted for maternal
age, race/ethnicity, parity,
prepregnancy BMI,
gestational weight gain,
infant sex, and gestational
age at OGTT
1,112/
7,020
100.0%
1.32 (1.06, 1.63)
yes
1.36 (1.00,1.85) yes
Changed to not
Adjusted for maternal
age, race/ethnicity, parity, statistically
significant
prepregnancy BMI,
gestational weight gain,
infant sex, and gestational
age at OGTT
Black, 2010
69/391
IADPSG IGT vs. IGT-2
179/886
100.0%
0.87 [0.68, 1.12]
no
n/a
n/a
No change.
Black, 2010
69/391
IADPSG IGT vs. IGT IFG
Black, 2010
69/391
IADPSG IFG vs. IGT-2
19/83
100.0%
0.77 (0.49, 1.21)
no
n/a
n/a
No change.
69/331
100.0%
0.85 (0.63, 1.14)
no
n/a
n/a
No change.
Black, 2010
19/83
100.0%
0.88 (0.58, 1.34)
no
n/a
n/a
No change.
69/331
100.0%
0.97 (0.76, 1.24)
no
n/a
n/a
No change.
Black, 2010
19/83
69/331
MATERNAL BIRTH TRAUMA
CC GDM vs no GDM
Cheng, 2009
31/273
1,255/
13,940
100.0%
1.10 (0.70, 1.72)
no
n/a
n/a
No change.
yes
1.16 (0.73,1.86) no
Parity, maternal age, race No change
or ethnicity, gestational
weight gain, gestational
age at delivery, year of
Black, 2010
179/
886
IADPSG IGT-2 vs no GDM
Black, 2010
19/83
IADPSG IGT IFG vs. no GDM
Black, 2010
69/331
IADPSG IGT vs. IFG
179/886
IADPSG IFG vs. IGT IFG
Black, 2010
179/886
IADPSG IGT-2 vs. IGT IFG
100.0%
1.26 (0.90, 1.76)
G-10
delivery, epidural
anesthesia, induction of
labor, (with mode of
delivery and episiotomy
additionally controlled for
perineal laceration,
postpartum hemorrhage,
shoulder dystocia, and
birth trauma)
CC GDM vs false-positive
Berggren, 2011 14/460
118/3,117 100.0%
0.80 (0.47, 1.39)
yes
0.83 (0.48, 1.44) no
Parity, maternal delivery
age over 35 years,
ethnicity, delivery year;
cesarean and operative
deliveries were also
controlled for prior
cesarean.
NDDG GDM vs no GDM
Adams, 1998
2/16
4/64
100.0% 2.00 (0.40, 9.97)
no
n/a
n/a
MATERNAL WEIGHT GAIN
CC 1 abnormal OGTT vs no GDM
Rust, 1996
36/78
38/205
100.0% 2.49 (1.71, 3.62)
no
n/a
n/a
WHO IGT vs. No GDM (data presented are mean (SD), n for each group; weight; and mean difference with 95% CI)
Yang, 2002
15.4 (6.5), 15.4 (5.6), 100.0% 0.00 (-1.41, 1.41)
no
n/a
n/a
102
302
IADPSG IGT vs. NO GDM (data presented are mean (SD), n for each group; weight; and mean difference with 95% CI)
Black, 2010
27.1 (14.5), 29.0
100.0% -1.90 (-3.37, -0.43) no
n/a
n/a
391
(13.7),
7,020
IADPSG IFG vs NO GDM (data presented are mean (SD), n for each group; weight; and mean difference with 95% CI)
Black, 2010
27.8 (15.2), 29.0
100.0% -1.20 (-2.25, -0.15) no
n/a
n/a
886
(13.7),
7,020
IADPSG IGT-2 vs. NO GDM (data presented are mean (SD), n for each group; weight; and mean difference with 95% CI)
Black, 2010
26.4 (11.6), 29.0
100.0% -2.60 (-5.12, -0.08) no
n/a
n/a
83
(13.7),
7,020
IADPSG IGT IFG vs. NO GDM (data presented are mean (SD), n for each group; weight; and mean difference with 95% CI)
Black, 2010
27.8 (14.8), 29.0
100.0% -1.20 (-2.83, 0.43)
no
n/a
n/a
331
(13.7),
7,020
G-11
No change
No change
No change
No change
No change
No change
No change
IADPSG IGT vs. IFG (data presented are mean (SD), n for each group; weight; and mean difference with 95% CI)
Black, 2010
27.1 (14.5), 27.8
100.0% -0.70 (-2.45, 1.05)
no
n/a
n/a
391
(15.2),
886
IADPSG IGT vs IGT-2 (data presented are mean (SD), n for each group; weight; and mean difference with 95% CI)
No change
Black, 2010
27.1 (14.5), 26.4
100.0% 0.70 (-2.18, 3.58)
no
n/a
n/a
391
(11.6),
83
IADPSG IGT vs. IGT IFG (data presented are mean (SD), n for each group; weight; and mean difference with 95% CI)
Black, 2010
27.1 (14.5), 27.8
100.0% -0.70 (-2.85, 1.45)
no
n/a
n/a
391
(14.8),
331
IADPSG IFT vs. IGT-2 (data presented are mean (SD), n for each group; weight; and mean difference with 95% CI)
No change
Black, 2010
27.8 (15.2), 26.4
100.0% 1.40 (-1.29, 4.09)
no
n/a
n/a
886
(11.6),
83
IADPSG IFG vs. IGT IFG (data presented are mean (SD), n for each group; weight; and mean difference with 95% CI)
No change
Black, 2010
27.8 (15.2), 27.8
100.0% 0.00 (-1.88, 1.88)
no
n/a
n/a
886
(14.8),
331
IADPSG IGT-2 vs. IGT IFG (data presented are mean (SD), n for each group; weight; and mean difference with 95% CI)
Black, 2010
26.4 (11.6), 27.8
100.0% -1.40 (-4.36, 1.56)
no
n/a
n/a
83
(14.8),
331
MATERNAL MORBIDITY/MORTALITY
CC GDM vs no GDM
No change
Lapolla, 2011
26/112
299/1,815 100.0%
CC 1 ABNORMAL OGTT vs NO GDM
1.53 (0.97, 2.42)
no
n/a
n/a
No change
Rust, 1996
5/78
IADPSG GDM vs no GDM
Lapolla, 2011
26/112
100.0%
1.01 (0.37, 2.74)
no
n/a
n/a
No change
294/1,815 100.0%
1.43 (1.01, 2.04)
no
n/a
n/a
No change
13/205
No change
No change
* The information presented in these columns is number of patients with the outcome / numbers of patients per group, except where otherwise indicated.
† The effect estimates are risk ratios with 95% confidence intervals, unless otherwise indicated.
BMI = body mass index; CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; IADPSG = International Association of Diabetes and Pregnancy
Study Groups; IFG = impaired fasting glucose; IFT = impaired fasting tolerance; IGT = impaired glucose tolerance; IGT-2 = double impaired glucose tolerance; NDDG = National
Diabetes Data Group; n = number of patients with the outcome; N = numbers of patients per group; n/a = not applicable; OGTT = oral glucose tolerance test; PIH = Pregnancy
induced hypertension;SD = standard deviation; WHO = World Health Organization
G-12
Table G-2. Offspring outcomes: Unadjusted data included in meta-analyses for Key Question 3 and adjusted effect estimates where
available from included studies
Author, Year
n/N*
n/N*
Weight
Effect estimate
†
(95% CI)
Were
there
adjusted
results?
Adjusted
effect
estimate
(95% CI)
Adjusted
results
different
Variables in model
Impact of adjusted
results on pooled
estimates
Macrosomia >4,500 g
CC GDM vs. no GDM
Cheng, 2009
11/273
223/13,940 50.7%
2.52 (1.39, 4.56)
Yes
4.47 (2.26, 8.86)
no
56/2,940
108/4,190
21,070
30.6%
18.7%
100.0%
3.20 (1.49, 6.86)
1.71 (0.64, 4.53)
2.52 (1.65, 3.84)
no
no
n/a
n/a
n/a
n/a
Naylor, 1996
7/115
12/580
Schwartz, 1999 4/91
28/605
Total (95% CI) 206
1185
CC false positive vs. no GDM
Naylor, 1996
12/580
56/2940
Schwartz, 1999 28/605
108/4,190
Total (95% CI) 1,185
7,130
52.2%
47.8%
100.0%
2.94 (1.18, 7.31)
0.95 (0.34, 2.64)
1.71 (0.56, 5.24)
no
no
39.0%
61.0%
100.0%
1.09 (0.59, 2.01)
1.80 (1.20, 2.70)
1.48 (0.91, 2.39)
no
no
Naylor, 1996
7/115
Schwartz, 1999 4/91
Total (95% CI) 479
Parity, maternal age,
race or ethnicity,
gestational weight
gain, gestational age
at delivery, year of
delivery, epidural
anesthesia, induction
of labor, (with mode of
delivery and
episiotomy
additionally controlled
for perineal laceration,
postpartum
hemorrhage, shoulder
dystocia, and birth
trauma)
No difference in
significance if
adjusted estimate
was added; may
increase estimate of
RR
CC vs. false-positive
n/a
n/a
n/a
n/a
No change
n/a
n/a
n/a
n/a
No change
G-13
NDDG GDM vs no GDM
Adams, 1998
3/16
Macrosomia >4,000 g
CC GDM vs. no GDM
0/64
100.0%
26.76 (1.45, 493.62)
no
n/a
n/a
Berkus, 1995
Chico, 2005
Chou, 2010
Hillier, 2007
Langer, 2005
Lapolla, 2011
Naylor, 1996
13/72
22/422
22/489
25/173
93/555
12/112
33/115
76/573
288/5,767
236/1,0116
905/7,609
87/1,110
145/1,815
395/2,940
7.4%
10.1%
10.0%
11.8%
15.5%
7.0%
14.3%
1.36 (0.80, 2.32)
1.04 (0.68, 1.59)
1.93 (1.26, 2.96)
1.21 (0.84, 1.75)
2.14 (1.63, 2.81)
1.34 (0.77, 2.34)
2.14 (1.58, 2.89)
no
no
no
no
no
no
no
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
Pennison, 2001
6/43
5/69
2.2%
1.93 (0.63, 5.93)
no
Ricart, 2005
21/263
292/6,350
10.0%
1.74 (1.13, 2.66)
yes
1.45 (0.83, 2.52)
yes
Schwartz, 1999
Total (95% CI)
22/91
2335
692/4,190
40,539
11.7%
100.0%
1.46 (1.01, 2.12)
1.61 (1.35, 1.92)
no
n/a
n/a
No change
Maternal BMI, fetal
sex (male),
gestational age,
maternal age,
macrosomia (yes),
PIH (yes)
Adding adjusted
value would not
change significance
CC GDM vs. false-positive
Berggren, 2011
78/460
411/3,117
30.1%
1.29 (1.03, 1.60)
yes
1.25 (1.01,1.56)
no
Hillier, 2007
Naylor, 1996
25/173
33/115
122/999
80/580
17.3%
20.0%
1.18 (0.79, 1.76)
2.08 (1.46, 2.96)
no
no
n/a
n/a
Ricart, 2005
21/263
131/1,838
15.2%
1.12 (0.72, 1.74)
no
n/a
n/a
Schwartz, 1999
Total (95% CI)
22/91
1,102
119/605
7,139
17.4%
100.0%
1.23 (0.83, 1.83)
1.36 (1.10, 1.68)
no
n/a
n/a
Parity, maternal
delivery age over 35
years, ethnicity,
delivery year;
cesarean and
operative deliveries
were also controlled
for prior cesarean
Adding adjusted
value would not
change significance
G-14
CC GDM vs 1 abnormal OGTT
Berkus, 1995
13/72
18/87
Chico, 2005
22/422
3/59
Hillier, 2007
25/173
40/288
Total (95% CI) 667
434
CC 1 abnormal OGTT vs. no GDM
Berkus, 1995
18/87
76/573/
Chico, 2005
3/59
288/5,767
Corrado, 2009
19/152
39/624
Hillier, 2007
40/288
905/7,609
Lapolla, 2007
3/48
8/334
Rust, 1996
6/78
18/205
Vambergue,
21/131
8/108
2000
Total (95% CI)
843
15,220
31.1%
9.3%
59.7%
100.0%
0.87 (0.46, 1.66)
1.03 (0.32, 3.32)
1.04 (0.66, 1.65)
0.98 (0.69, 1.41)
no
no
no
20.8%
4.4%
17.2%
39.0%
3.3%
6.7%
8.6%
1.56 (0.98, 2.48)
1.02 (0.34, 3.08)
2.00 (1.19, 3.36)
1.17 (0.87, 1.57)
2.61 (0.72, 9.50)
0.88 (0.36, 2.13)
2.16 (1.00, 4.69)
no
no
yes
no
no
no
yes
100.0%
1.44 (1.13, 1.82)
n/a
n/a
n/a
n/a
n/a
n/a
No change
n/a
n/a
2 (1.13, 3.61)
n/a
n/a
n/a
n/a
no
n/a
n/a
2.5 (1.16, 5.4)
yes
Age and BMI
Pre-pregnancy, BMI >
27, maternal age >35,
multiparity,
educational level.
Adding adjusted
estimates would not
change significance
of overall result
CC false-positive vs. no GDM
Hillier, 2007
Lapolla, 2007
Naylor, 1996
Ricart, 2005
122/999
8/128
80/580
131/1838
905/7,609
8/334
395/2,940
21/263
43.8%
3.8%
35.9%
14.9%
1.03 (0.86, 1.23)
2.61 (1.00, 6.81)
1.03 (0.82, 1.28)
0.89 (0.57, 1.39)
no
no
no
yes
n/a
n/a
n/a
n/a
1.33 (1.04, 1.72)
yes
Schwartz, 1999
Total (95% CI)
2/49
3,594
12/112
11,258
1.7%
100.0%
0.38 (0.09, 1.64)
1.02 (0.85, 1.24)
no
n/a
n/a
51.7%
37.8%
10.6%
1.14 (0.82, 1.59)
2.04 (1.23, 3.39)
1.00 (0.28, 3.61)
no
no
no
Adding adjusted
estimates would not
change significance
of overall result
CC 1 abnormal OGTT vs. false-positive
Hillier, 2007
Kwik, 2007
Lapolla, 2007
40/288
42/213
3/48
122/999
19/197
8/128
Maternal BMI, fetal
sex (male),
gestational age,
maternal age,
macrosomia (yes),
PIH (yes)
G-15
n/a
n/a
n/a
n/a
n/a
n/a
Total (95% CI) 549
NDDG vs no GDM
Adams, 1998
7/16
1,324
100.0%
1.40 (0.89, 2.20)
No change
5/64
100.0%
5.60 (2.04, 15.35)
no
No change
NDDG false positive vs no GDM
Chico, 2005
Hillier, 2007
Retnakaran,
2008
Stamilio, 2004
15/187
27/326
18/128
33/529
83/1,432
6/74
21.6%
42.9%
9.7%
1.29 (0.71, 2.31)
1.43 (0.94, 2.17)
1.73 (0.72, 4.18)
no
no
no
n/a
n/a
n/a
n/a
n/a
n/a
14/164
95/1,661
25.8%
1.49 (0.87, 2.56)
yes
1.79 (0.91, 3.51)
no
Total (95% CI)
805
3,696
100.0%
1.44 (1.10, 1.89)
16/532
100.0%
3.33 (0.49, 22.70)
no
1.34 (0.15, 12)
no
No change
696/2,596
100.0%
1.26 (1.06, 1.50)
yes
1.5 (1.1, 2.2)
no
Pre-pregnancy BMI, No change
maternal age,parity,
smoking, weight gain
during pregnancy,
gestational age,
anamnestic risk
indicators for GDM,
ethnic background
and clinical centre.
145/1,815
78.8%
1.34 (0.77, 2.34)
no
n/a
n/a
WHO GDM vs no GDM
Shirazian, 2008 1/10
BMI, parity,
gestational age at
delivery, chronic
hypertension, tobacco
use, race,
midtrimester serum Bfetoprotein and
human chorionic
gonadotropin levels,
maternal age, history
of preeclampsia in
previous pregnancy
Adding adjusted
estimate would not
change significance
of overall result
WHO IGT vs no GDM
Jensen, 2003
98/289
IADPSG GDM vs no GDM
Lapolla, 2011
12/112
G-16
Morikawa, 2010 1/43
Total (95% CI) 155
Shoulder dystocia
CC GDM vs. no GDM
0/160
1,975
21.2%
100.0%
10.98 (0.46, 264.81)
2.09 (0.39, 11.33)
no
Cheng, 2009
9/273
237/
13,940
48.40%
1.94 (1.01, 3.73)
yes
2.24 (1.03,4.88)
no
Chou, 2010
Landon, 2011
2/489
18/455
11/10,116
3/423
9.2%
14.1%
3.76 (0.84, 16.92)
5.58 (1.65, 18.80)
no
yes
n/a
5.44 (1.81, 20.1)
n/a
no
Langer, 2005
Pennison, 2001
Total (95% CI)
14/555
1/43
1,815
7/1,110
1/69
25,658
25.6%
2.8%
100.0%
4.00 (1.62, 9.85)
1.60 (0.10, 24.99)
2.86 (1.81, 4.51)
no
no
n/a
n/a
n/a
n/a
100.0%
1.49 (0.97, 2.30)
yes
CC GDM vs. false-positive
Berggren, 2011 24/460
109/3,117
n/a
n/a
No change
Parity, maternal age,
race or ethnicity,
gestational weight
gain, gestational age
at delivery, year of
delivery, epidural
anesthesia, induction
of labor, (with mode of
delivery and
episiotomy
additionally controlled
for perineal laceration,
postpartum
hemorrhage, shoulder
dystocia, and birth
trauma)
Maternal age,
gestational age at
enrollment and at
delivery, parity, BMI,
and race and ethnicity
Adding adjusted
estimate would not
change significance
of overall result
CC 1 abnormal OGTT vs. no GDM
G-17
1.41 (0.91,2.18)
no
Parity, maternal
delivery age over 35
years, ethnicity,
delivery year;
cesarean and
operative deliveries
were also controlled
for prior cesarean
No change
Vambergue,
1/131
4/108
100.0%
2000
CC 1 abnormal OGTT vs. false-positive
Kwik, 2007
11/213
2/197
100.0%
NDDG GDM (unrecognized) vs. no GDM
Adams, 1998
3/16
2/64
100.0%
0.20 (0.02, 1.82)
no
n/a
n/a
No change
5.09 (1.14, 22.66)
no
n/a
n/a
No change
6.00 (1.09, 32.95)
yes
5.2 (1.1, 30.6)
no
Maternal BMI, age,
parity, weight gain,
gestational age
No change
NDDG false-positive vs. no GDM
Stamilio, 2004
8/164
29/1,661
100.0%
2.79 (1.30, 6.01)
yes
2.85 (1.25, 6.51)
no
No change
BMI, parity,
gestational age at
delivery, chronic
hypertension, tobacco
use, race,
midtrimester serum Bfetoprotein and
human chorionic
gonadotropin levels,
maternal age, history
of preeclampsia in
previous pregnancy
WHO IGT vs. no GDM
Jensen, 2003
8/289
33/2,596
100.0%
2.18 (1.02, 4.67)
yes
1.3 (0.4, 3.9)
yes
Pre-pregnancy BMI, Adjusted estimate
maternal age,parity, not statistically
smoking, weight gain significant
during pregnancy,
gestational age,
anamnestic risk
indicators for GDM,
ethnic background
and clinical centre.
IADPSG IGT vs. no GDM
Black, 2010
18/391
268/7,020
100.0%
1.21 (0.76, 1.92)
yes
1.31 (0.80, 2.16)
no
Adjusted for maternal No change
age, race/ethnicity,
parity, prepregnancy
BMI, gestational
weight gain, infant
sex, and gestational
age at OGTT
IADPSG IFG vs. no GDM
G-18
268/7,020
100.0%
1.48 (1.10, 1.98)
yes
1.45 (1.05, 2.00)
no
Adjusted for maternal No change
age, race/ethnicity,
parity, prepregnancy
BMI, gestational
weight gain, infant
sex, and gestational
age at OGTT
IADPSG IGT-2 vs. no GDM
Black, 2010
5/83
268/7,020
100.0%
1.58 (0.67, 3.72)
yes
1.72 (0.68, 4.35)
no
Adjusted for maternal No change
age, race/ethnicity,
parity, prepregnancy
BMI, gestational
weight gain, infant
sex, and gestational
age at OGTT
IADPSG IGT IFG vs. no GDM
Black, 2010
23/331
268/7,020
100.0%
1.82 (1.21, 2.75)
yes
1.87 (1.18, 2.96)
no
Adjusted for maternal No change
age, race/ethnicity,
parity, prepregnancy
BMI, gestational
weight gain, infant
sex, and gestational
age at OGTT
IADPSG IGT vs. IFG
Black, 2010
18/391
50/886
100.0%
0.82 (0.48, 1.38)
no
n/a
n/a
No change
IADPSG IGT vs. IGT-2
Black, 2010
18/391
5/83
100.0%
0.76 (0.29, 2.00)
no
n/a
n/a
No change
23/331
100.0%
0.66 (0.36, 1.21)
no
n/a
n/a
No change
5/83
100.0%
0.94 (0.38, 2.28)
no
n/a
n/a
No change
23/331
100.0%
0.81 (0.50, 1.31)
no
n/a
n/a
No change
23/331
100.0%
0.87 (0.34, 2.21)
no
n/a
n/a
No change
Black, 2010
50/886
IADPSG IGT vs. IGT IFG
Black, 2010
18/391
IADPSG IFG vs. IGT-2
Black, 2010
50/886
IADPSG IFT vs. IGT IFG
Black, 2010
50/886
IADPSG IGT-2 vs. IGT IFG
Black, 2010
5/83
G-19
Fetal birth injury
NDDG GDM (unrecognized) vs. no GDM
Adams, 1998
4/16
0/64
100.0%
No change
34.41 (1.95, 608.47) no
n/a
n/a
35.1%
34.8%
30.1%
100.0%
1.56 (1.02, 2.37)
9.52 (6.02, 15.08)
3.21 (1.18, 8.76)
3.64 (0.96, 13.76)
no
no
no
n/a
n/a
n/a
n/a
n/a
n/a
100.0%
3.22 (0.44, 23.37)
no
n/a
n/a
4.0%
27.8%
27.4%
40.0%
0.48 (0.07, 3.39)
1.42 (0.68, 2.97)
1.18 (0.56, 2.48)
1.41 (0.77, 2.60)
no
no
no
no
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
100.0%
1.29 (0.88, 1.91)
Not
estimable
n/a
n/a
n/a
n/a
No change
100.00%
2.83 (0.58, 13.89)
no
n/a
n/a
No change
100.00%
9.60 (0.86, 106.73) no
n/a
n/a
No change
WHO IGT vs. WHO no GDM
Jensen, 2003
6/281
63/2,596
76.60%
0.88 (0.38, 2.01)
yes
0.7 (0.2, 2.2)
no
Nord, 1995
Yang, 2002
16.50%
6.90%
1.17 (0.20, 6.94)
2.96 (0.19, 46.91)
no
no
n/a
n/a
n/a
n/a
Neonatal hypoglycemia
CC GDM vs. No GDM
Chico, 2005
23/422
202/5,767
Langer, 2005
100/555 21/1,110
Pennison, 2001 10/43
5/69
Total (95% CI) 1,020
6,946
CC GDM vs. 1 abnormal OGTT
Chico, 2005
23/422
1/59
CC 1 abnormal OGTT vs. no GDM
Chico, 2005
1/59
202/5,767
Corrado, 2009
9/152
26/624
Rust, 1996
9/78
20/205
Vambergue,
24/131
14/108
2000
Total (95% CI)
420
6,704
NDDG GDM vs. No GDM
Adams, 1998
0/16
0/64
NDDG false-positive vs. no GDM
Ardawi, 2000
3/187
3/529
NDDG 1 abnormal vs. no GDM
Kim, 2002
2/122
1/577
2/223
1/102
3/391
1/302
No change
No change
G-20
Pre-pregnancy BMI,
maternal age,parity,
smoking, weight gain
during pregnancy,
gestational age,
anamnestic risk
indicators for GDM,
ethnic background
and clinical centre.
Total (95% CI)
606
3,289
Hyperbilirubinemia
CC GDM vs. No GDM
Chico, 2005
17/422
144/5,767
Langer, 2005
78/555
23/1,110
Total (95% CI) 977
6,877
CC GDM vs. 1 abnormal OGTT
Chico, 2005
17422/
1/59
CC false-positive vs. no GDM
Bo, 2004
42/315
4/91
CC 1 abnormal OGTT vs. no GDM
Vambergue,
2/131
0/108
2000
NDDG false-positive vs. no GDM
Ardawi, 2000
22/187
58/529
WHO IGT vs. WHO no GDM
Jensen, 2003
6/281
83/2,596
Nord, 1995
10/223
28/391
Total (95% CI) 504
2,987
IADPSG IGT vs. no GDM
Black, 2010
72/391
980/7,020
IADPSG IFG vs. no GDM
Black, 2010
128/886
980/7,020
100.00%
1.00 (0.49, 2.07)
Adding adjusted
estimate would not
change statistical
significance of
overall result
49.80%
50.20%
100.00%
1.61 (0.99, 2.64)
6.78 (4.31, 10.68)
3.32 (0.80, 13.74)
no
no
100.00%
2.38 (0.32, 17.53)
no
n/a
n/a
No change
100.00%
3.03 (1.12, 8.23)
no
n/a
n/a
No change
100.00%
4.19 (0.20, 88.20)
no
n/a
n/a
No change
100.00%
1.07 (0.68, 1.70)
no
n/a
n/a
No change
42.40%
57.60%
100.00%
0.67 (0.29, 1.52)
0.63 (0.31, 1.26)
0.64 (0.38, 1.10)
no
no
n/a
n/a
n/a
n/a
100.00%
1.32 (1.06, 1.64)
yes
1.33 (1.02, 1.74)
no
Adjusted for maternal No change
age, race/ethnicity,
parity, prepregnancy
BMI, gestational
weight gain, infant
sex, and gestational
age at OGTT
100.00%
1.03 (0.87, 1.23)
yes
1.04 (0.85, 1.27)
no
Adjusted for maternal No change
age, race/ethnicity,
parity, prepregnancy
BMI, gestational
weight gain, infant
sex, and gestational
age at OGTT
n/a
n/a
n/a
n/a
No change
No change
IADPSG IGT-2 vs. no GDM
G-21
980/7,020
100.00%
1.55 (1.03, 2.35)
yes
1.56 (0.92, 2.65)
yes
Adjusted for maternal Adjusted result is
not statistically
age, race/ethnicity,
parity, prepregnancy significant
BMI, gestational
weight gain, infant
sex, and gestational
age at OGTT
IADPSG IGT OFG vs. no GDM
Black, 2010
45/331
980/7,020
100.00%
0.97 (0.74, 1.29)
yes
0.96 (0.69, 1.33)
no
Adjusted for maternal No change
age, race/ethnicity,
parity, prepregnancy
BMI, gestational
weight gain, infant
sex, and gestational
age at OGTT
IADPSG IGT vs. IFG
Black, 2010
72/391
128/886
100.0%
1.27 (0.98, 1.66)
no
n/a
n/a
No change
18/83
100.0%
0.85 (0.54, 1.34)
no
n/a
n/a
No change
45/331
100.0%
1.35 (0.96, 1.91)
no
n/a
n/a
No change
128/
18/83
886
IADPSG IFG vs. IGT IFG
Black, 2010
128/
45/331
886
IADPSG IGT-2 vs. IGT IFG
Black, 2010
18/83
45/331
100.0%
0.67 (0.43, 1.03)
no
n/a
n/a
No change
100.0%
1.06 (0.78, 1.46)
no
n/a
n/a
No change
100.0%
1.60 (0.98, 2.61)
no
n/a
n/a
No change
1.19 (0.68, 2.08)
yes
1.26 (0.66, 2.42)
no
Parity, maternal age, No change
race or ethnicity,
gestational weight
gain, gestational age
at delivery, year of
delivery, epidural
anesthesia, induction
Black, 2010
18/83
IADPSG IGT vs. IGT-2
Black, 2010
72/391
IADPSG IGT vs. IGT IFG
Black, 2010
72/391
IADPSG IFG vs. IGT-2
Black, 2010
Fetal Birth Trauma/ Injury
CC GDM vs. no GDM
Cheng, 2009
12/273
516/13,940 100.00%
G-22
of labor, (with mode of
delivery and
episiotomy
additionally controlled
for perineal laceration,
postpartum
hemorrhage, shoulder
dystocia, and birth
trauma)
NDDG GDM vs. No GDM
Adams, 1998
4/16
WHO IGT vs. no GDM
Nord, 1995
1/223
Yang, 2002
0/102
0/64
100.0%
34.41 (1.95, 608.47) no
n/a
no
6/391
0/302
100.00%
0.00%
0.29 (0.04, 2.41)
Not estimable
n/a
n/a
n/a
n/a
693
100.00%
0.29 (0.04, 2.41)
Fetal Morbidity/Mortality
CC GDM vs. no GDM
Chico, 2005
0/422
Chou, 2010
1/489
Langer, 2005
0/555
Lapolla, 2011
18/112
Ricart, 2005
0/263
29/5,767
42/10,116
0/1,110
132/1,815
25/6350
10.10%
16.80%
46.80%
10.10%
0.23 (0.01, 3.78)
0.49 (0.07, 3.57)
Not estimable
2.21 (1.40, 3.48)
0.47 (0.03, 7.73)
no
no
no
no
no
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
Schwartz, 1999
Total (95% CI)
16/7,207
32,365
16.40%
100.00%
2.92 (0.39, 21.92)
1.23 (0.46, 3.30)
no
n/a
n/a
CC GDM vs. false-positive
Ricart, 2005
0/263
7/1,838
49.10%
0.46 (0.03, 8.11)
no
n/a
n/a
Schwartz, 1999
Total (95% CI)
50.90%
100.00%
6.92 (0.44, 110.10) no
1.83 (0.11, 29.41)
n/a
n/a
n/a
Not estimable
no
n/a
n/a
3.40%
93.90%
2.60%
1.63 (0.10, 26.36)
0.99 (0.58, 1.68)
2.48 (0.10, 60.20)
no
no
no
n/a
n/a
n/a
n/a
n/a
n/a
100.00%
1.03 (0.61, 1.72)
Total (95% CI)
325
1/154
1,995
1/154
417
1/1,066
2,904
CC GDM vs. 1 abnormal OGTT
Chico, 2005
0/422
0/59
CC 1 abnormal OGTT vs. no GDM
Chico, 2005
0/59
29/5,767
Rust, 1996
15/78
40/205
Vambergue,
1/131
0/108
2000
Total (95% CI)
268
6,080
no
no
No change
No change
No change
No change
No change
No change
CC false-positive vs. no GDM
G-23
Bo, 2004
Ricart, 2005
4/315
7/1,838
2/91
25/6,350
17.40%
70.50%
0.58 (0.11, 3.10)
0.97 (0.42, 2.23)
no
no
n/a
n/a
n/a
n/a
Schwartz, 1999
Total (95% CI)
1/1,066
3,219
16/7,207
13,648
12.10%
100.00%
0.42 (0.06, 3.18)
0.80 (0.40, 1.61)
no
n/a
n/a
No change
CC false-positive vs. 1 abnormal OGTT
Kwik, 2007
0/197
0/213
n/a
NDDG false-positive vs. no GDM
Ardawi, 2000
2/187
4/529
47.00%
Stamilio, 2004
2/164
6/1,661
53.00%
Not estimable
no
n/a
1.41 (0.26, 7.66)
3.38 (0.69, 16.59)
no
yes
n/a
n/a
4.61 (0.77, 27.48) no
Total (95% CI)
100.00%
2.24 (0.70, 7.14)
NDDG 1 abnormal OGTT vs. no GDM
Kim, 2002
0/122
2/577
100.00%
0.94 (0.04, 19.69)
no
n/a
n/a
WHO IGT vs. no GDM
Aberg, 2001
1/126
13/4,515
22.90%
2.76 (0.36, 20.91)
no
n/a
n/a
Nord, 1995
Yang, 2002
3/223
2/102
7/391
2/302
52.20%
24.80%
0.75 (0.20, 2.88)
2.96 (0.42, 20.75)
no
no
n/a
n/a
n/a
n/a
Total
451
5,208
100.0%
1.42 (0.54, 3.75)
351
2,190
IADPSG GDM vs. no GDM
Lapolla, 2011 18/112
132/1,815 100.00%
2.21 (1.40, 3.48)
Prevalence of Childhood Obesity (>85th percentile)
CC GDM vs. no GDM
Hillier, 2007
60/173
1788/7,609 100.00%
1.48 (1.20, 1.82)
No change
n/a
BMI, parity,
gestational age at
delivery, chronic
hypertension, tobacco
use, race,
midtrimester serum Bfetoprotein and
human chorionic
gonadotropin levels,
maternal age, history
of preeclampsia in
previous pregnancy
Adding adjusted
estimate would not
change significance
of overall result
No change
No change
no
n/a
n/a
yes
1.89 (1.30, 2.76)
no
G-24
No change
Maternal age, parity,
weight gain during
pregnancy, ethnicity,
macrosomia at birth
No change
(4,000 g), and sex of
child
CC GDM vs. false-positive
Hillier, 2007
60/173
233/999
100.00%
CC GDM vs. 1 abnormal OGTT
Hillier, 2007
60/173
77/288
100.00%
CC false-positive vs. no GDM
Hillier, 2007
233/999
1788/7,609 100.00%
CC false-positive vs. 1 abnormal OGTT
Hillier, 2007
233/999
77/288
100.00%
CC 1 abnormal OGTT vs. no GDM
Hillier, 2007
77/288
1788/7,609 100.00%
1.49 (1.18, 1.88)
no
n/a
n/a
No change
1.30 (0.98, 1.72)
no
n/a
n/a
No change
0.99 (0.88, 1.12)
yes
0.98 (0.81, 1.17)
no
0.87 (0.70, 1.09)
no
n/a
n/a
1.14 (0.94, 1.38)
yes
1.37 (1.01, 1.84)
yes (result Maternal age, parity,
becomes weight gain during
significant) pregnancy, ethnicity,
macrosomia at birth
(4,000 g), and sex of
child
Maternal age, parity,
weight gain during
pregnancy, ethnicity,
macrosomia at birth
(4,000 g), and sex of
child
No change
No change
* The information presented in these columns is number of patients with the outcome / numbers of patients per group.
† The effect estimates are risk ratios with 95% confidence intervals.
BMI = body mass index; CC = Carpenter-Coustan; CI = confidence interval; GDM = gestational diabetes mellitus; IADPSG = International Association of Diabetes and Pregnancy
Study Groups; IFG = impaired fasting glucose; IFT = impaired fasting tolerance; IGT = impaired glucose tolerance; IGT-2 = double impaired glucose tolerance; NDDG = National
Diabetes Data Group; n = number of patients with the outcome; N = numbers of patients per group; n/a = not applicable; OGTT = oral glucose tolerance test; PIH = Pregnancy
induced hypertension;SD = standard deviation; WHO = World Health Organization
G-25