in progress

Draft Recommendation Statement

Gestational Diabetes Mellitus: Screening

February 16, 2021

Recommendations made by the USPSTF are independent of the U.S. government. They should not be construed as an official position of the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services.

This topic is being updated. Please use the link(s) below to see the latest documents available.

Recommendation Summary

Population Recommendation Grade
Asymptomatic pregnant persons at 24 of gestation or after The USPSTF recommends screening for gestational diabetes mellitus (GDM) in asymptomatic pregnant persons at 24 weeks of gestation or after. B
Asymptomatic pregnant persons before 24 weeks of gestation The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for GDM in asymptomatic pregnant persons before 24 weeks of gestation. I

Additional Information

Tools
Related Resources
  • Screening for Gestational Diabetes Mellitus: Consumer Guide (Draft Recommendation) | Link to File

Full Recommendation:

Recommendations made by the USPSTF are independent of the U.S. government. They should not be construed as an official position of the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services.

Expand All

Gestational diabetes mellitus is diabetes developed during pregnancy.1-3 Prevalence of GDM in the United States has typically been estimated at 5.8% to 9.2%, based on traditional diagnostic criteria, although it may be higher if more inclusive criteria is used.4-8 Pregnant persons with GDM are at increased risk for maternal and fetal complications, including preeclampsia, fetal macrosomia (which can cause shoulder dystocia and birth injury), and neonatal hypoglycemia.3,9-11 Gestational diabetes mellitus has also been associated with an increased risk of several long-term health outcomes in mothers and intermediate outcomes in their offspring.12-16

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Pregnant Persons at 24 Weeks of Gestation or After

The USPSTF concludes with moderate certainty that there is a moderate net benefit to screening for GDM at 24 weeks of gestation or after to improve maternal and fetal outcomes.

Pregnant Persons Before 24 Weeks of Gestation

The USPSTF concludes that the evidence on screening for GDM before 24 weeks of gestation is insufficient, and the balance of benefits and harms of screening cannot be determined.

See Table 1 for more information on the USPSTF recommendation rationale and assessment. For more details on the methods the USPSTF uses to determine the net benefit, see the USPSTF Procedure Manual.17

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Patient Population Under Consideration

This recommendation applies to pregnant persons who have not been previously diagnosed with type 1 or type 2 diabetes mellitus.

Definitions of GDM

During pregnancy, insulin resistance increases, leading to higher glucose intolerance and development of GDM in some pregnant persons. In the past, GDM was defined as glucose intolerance discovered during pregnancy; however, this definition does not distinguish between persons with glucose intolerance related to pregnancy and those with preexisting, overt diabetes that is previously undiagnosed.18 Because of this, several organizations, such as the American Diabetes Association, have updated the definition to specify GDM as diabetes that develops during pregnancy that is not clearly overt diabetes that develops prior to pregnancy.2,3

Assessment of Risk

Several factors increase a person’s risk for developing GDM, including obesity, increased maternal age, history of GDM, family history of diabetes, and belonging to an ethnic/racial group that has increased risk for developing type 2 diabetes mellitus (Hispanic, Native American, South or East Asian, or Pacific Island descent).4,19,20 Much of the risk in different ethnic groups may be attributed to being overweight, obesity, and low socioeconomic status, with the exception of Asian Americans, in which higher GDM prevalence persists despite normal body mass index.21,22 Factors associated with a lower risk for developing GDM include age younger than 25 to 30 years, White race, a body mass index of 25 kg/m2 or less, no family history (in a first-degree relative) of diabetes, and no history of glucose intolerance or adverse pregnancy outcomes related to GDM.23-25

Screening Tests

Screening for GDM in asymptomatic persons involves either a two-step (screening test followed by a diagnostic test) or one-step (diagnostic test used for all patients) approach. In the United States, a two-step approach is commonly used.8,26 A 50-g oral glucose challenge test (OGCT) is performed between 24 and 28 weeks of gestation in a nonfasting state. If the screening threshold is met or exceeded, patients receive the oral glucose tolerance test (OGTT). During the OGTT, a fasting glucose level is obtained, followed by administration of a 75- or 100-g glucose load, then evaluation of glucose levels after 1, 2, and often 3 hours. A diagnosis of GDM is made when two or more glucose values fall at or above the specified glucose thresholds.27

In the one-step approach, a 75-g glucose load is administered after a fasting glucose level is obtained, and plasma glucose levels are evaluated after 1 and 2 hours. A diagnosis of GDM is made when one or more glucose values fall at or above the specified glucose thresholds.28

The American College of Obstetricians and Gynecologists recommends testing between 24 and 28 weeks of gestation.1 Pregnant persons whose first prenatal visit happens after 28 weeks of gestation (i.e., late entry into prenatal care) should be screened as soon as possible.

Treatment and Interventions

Initial treatment generally includes moderate physical activity, dietary changes, support from diabetes educators and nutritionists, and glucose monitoring. If the patient’s glucose is not controlled after these initial interventions, clinicians often prescribe medications (either insulin or oral hypoglycemic agents), perform increased surveillance in prenatal care, adopt changes in delivery management, or some combination thereof.1

Suggestions for Practice Regarding the I Statement

In deciding whether to screen for GDM before 24 weeks of gestation, primary care providers may consider the following.

Potential Preventable Burden

Between 2006 and 2016, there was an absolute increase of 3.6% in the prevalence of GDM. Pregnant persons with GDM are at increased risk for maternal and fetal complications and may benefit from early identification and treatment. They are also at increased risk for developing type 2 diabetes mellitus after pregnancy.29 Pregnant persons who are diagnosed with GDM before 24 weeks of gestation may be at even greater risk for maternal and fetal complications.29

Potential Harms

Potential harms of screening for GDM include psychological harms and intensive medical interventions (induction of labor, cesarean delivery, or admission to the neonatal intensive care unit [NICU]) that may be associated with a diagnosis of GDM. Possible adverse effects of treatment include neonatal or maternal hypoglycemia and maternal stress.

Current Practice

Although current data are limited, a 2014–2015 survey found that universal screening is the most common practice in the United States, with 90% of obstetricians reporting routinely screening for GDM using a two-step approach.26 Other potential (though not widely used) approaches to screening include fasting plasma glucose level, glycosylated hemoglobin (HbA1c) concentration, and risk-based screening tools. Some pregnant persons are screened earlier than 24 weeks of gestation because they have risk factors for type 2 diabetes mellitus, such as obesity, family history of type 2 diabetes mellitus, or fetal macrosomia during a previous pregnancy. If a pregnant person presents in the first trimester or in early pregnancy with risk factors for type 2 diabetes mellitus, clinicians should use their clinical judgment to determine what is appropriate screening for that individual patient, given the patient’s health needs.

Other Related USPSTF Recommendations

The USPSTF has several recommendations related to pregnancy and the prevention of GDM. This includes recommendations on screening for abnormal blood glucose and type 2 diabetes mellitus (B recommendation)30 and behavioral weight loss interventions to prevent obesity-related morbidity and mortality in adults (B recommendation),31 and a draft recommendation on healthy weight and weight gain during pregnancy (B recommendation).

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Scope of Review

To update the 2014 recommendation,32 the USPSTF commissioned a systematic review to evaluate the accuracy, benefits, and harms of screening for GDM and the benefits and harms of treatment for the mother and infant.29

Accuracy of Screening Tests and Risk Assessment

The USPSTF reviewed 45 prospective studies of fair or good quality that assessed the accuracy of various screening tests for GDM, including the 50-g OGCT, fasting plasma glucose level, HbA1c concentration, and screening based on risk factors. The reference standard in these studies was the diagnostic OGTT, but the cutoff thresholds used for GDM varied, with most using criteria from Carpenter and Coustan, the International Association of Diabetes and Pregnancy Study Group (IADPSG), and the National Diabetes Data Group (NDDG) (Table 2). In all studies, the entire study population that had a screening test (positive or negative) was offered the diagnostic OGTT reference standard. The studies were from a range of populations and settings, and the prevalence of GDM varied from 3.3% to 33%. Data on screening for GDM before 24 weeks of gestation were limited.29

Eight studies evaluated the accuracy of a 1-hour 50-g OGCT using a cutoff of 140 mg/dL (7.77 mmol/L) or lower. Gestational diabetes mellitus was confirmed by a 100-g 3-hour OGTT using either Carpenter and Coustan (8 studies), NDDG (6 studies), or IADPSG (2 studies) criteria. The 50-g OGCT showed good accuracy (sensitivity, 100% to 75%; specificity, 86% to 25%) using Carpenter and Coustan and NDDG criteria, with lower thresholds showing greater sensitivity but lower or imprecise specificity.29

The accuracy of fasting plasma glucose level (using various cutoffs) was evaluated against Carpenter and Coustan (7 studies), IADPSG (9 studies), and NDDG (1 study) diagnostic criteria. For screening using fasting plasma glucose level at 24 or more weeks of gestation, an 85- or 90-mg/dL cutoff had reasonable accuracy for a diagnosis using Carpenter and Coustan criteria, as did a 90-mg/dL cutoff using IADPSG criteria; values at 80 mg/dL or lower appeared useful to rule out GDM using both criteria.29 Two studies evaluated data for fasting plasma glucose measured before 24 weeks of gestation; however, findings were inconsistent.29

Eighteen studies compared HbA1c screening (using various cutoffs) to Carpenter and Coustan, NDDG, or IADPSG diagnostic criteria. Overall, HbA1c concentration was not associated with high sensitivity and specificity at any threshold. Risk-based tools (some in combination with fasting plasma glucose level) were evaluated against Carpenter and Coustan, NDDG, or IADPSG diagnostic criteria, each in a single study. Overall, these tools may have high enough sensitivity to rule out GDM (and allow some pregnant persons to avoid the OGCT); however, their specificity was low.29

Benefits of Early Detection and Treatment

Screening

No randomized, controlled trials (RCTs) addressed the direct benefits or harms of screening for GDM. Four observational studies (1 case-control, 3 retrospective cohorts) compared screening vs. no screening, but results were mixed. Of these, the two older studies found no benefit and the two newer studies (one with risk-based and one with universal screening strategies) found benefits in outcomes such as full-term stillbirth and reduced risk of cesarean delivery, birth injuries, and NICU admissions. However, the small number of studies, lack of consistency in effect between the studies, and the use of observational designs (which are susceptible to biases) limit findings.29

Five RCTs of good or fair quality compared the effectiveness of different screening strategies on health outcomes. Only one of these trials evaluated screening before 24 weeks of gestation. Three trials (n=1,059) compared IADPSG and Carpenter and Coustan screening criteria. Compared with Carpenter and Coustan, screening with IADPSG criteria identified twice as many cases of GDM and was associated with fewer primary (first) cesarean deliveries (2 RCTs; relative risk [RR], 0.73; absolute risk difference [ARD], 6.3%) and large for gestational age (LGA) infants (3 RCTs; RR, 0.46; ARD, 3.2%) and fewer episodes of neonatal hypoglycemia (2 RCTs; RR, 0.52; ARD, 2.7%). One of the studies contributing to most analyses was very small. Fewer NICU admissions (n=786; RR, 0.49; ARD, 3.7%) was found in a single study.29 One study comparing IADSPG criteria to World Health Organization 1999 criteria (n=502) found no difference in primary cesarean delivery and preterm delivery and imprecise findings for other maternal and fetal outcomes (i.e., hypertensive disorders, shoulder dystocia). One study (n=922) enrolling obese women compared early (14 to 20 weeks of gestation) to usual timed (24 to 28 weeks of gestation) screening using Carpenter and Coustan criteria. Earlier screening was associated with an increased risk of preeclampsia, although the finding was not statistically significant. No other differences were found among other maternal or fetal/neonatal outcomes.29

Treatment

Thirteen trials (11 RCTs and 2 nonrandomized, controlled trials; n=4,235) examined the effectiveness of GDM treatment on intermediate and health outcomes. The studies used a variety of glucose inclusion criteria and assessed short- and long-term outcomes in the mother and infant. Interventions included both dietary and medical therapies. Treatment was started after 24 weeks of gestation in nine trials (n=3,982), although in two of these trials, treatment was started earlier in pregnant persons deemed to be at high(er) risk and screened earlier. The three RCTs contributing most of the data used two-step approaches for identifying GDM before enrollment. Four trials (n=253) included women treated at less than 15 weeks of gestation. Race/ethnicity was fairly diverse in several studies, although two of the largest studies with treatment at or after 24 weeks of gestation enrolled large proportions of White (75%) and Chinese (97%) persons.29,33,34

Treatment of GDM at or after 24 weeks of gestation was associated with decreased risk of primary cesarean deliveries (RR, 0.70 [95% CI, 0.54 to 0.91]; ARD, 5.3%; 3 trials) and preterm deliveries, although findings for the latter are not statistically significant (RR, 0.75 [95% CI, 0.56 to 1.01]; ARD, 2.3%; 4 trials). Treatment of GDM was not associated with reduced preeclampsia in the included studies (RR, 0.99 [95% CI, 0.46 to 2.16]; 6 trials).29 Additionally, treatment was not associated with reduced risk of gestational hypertension (2 trials), total cesarean deliveries (8 trials), emergency cesarean deliveries (1 trial), induction of labor (5 trials), or maternal birth trauma (2 trials).29

For fetal/neonatal outcomes, treatment of GDM at or after 24 weeks of gestation was associated with reduced risk of shoulder dystocia (RR, 0.42 [95% CI, 0.23 to 0.77]; ARD, 1.3%; 3 trials), macrosomia (RR, 0.53 [95% CI, 0.41 to 0.68]; ARD, 8.9%; 8 trials), LGA infants (RR, 0.56 [95% CI, 0.47 to 0.66]; ARD, 8.4%; 7 trials), birth injury (e.g., fracture or nerve palsies) (odds ratio, 0.33 [95% CI, 0.11 to 0.99]; ARD, 0.2%) and NICU admissions (RR, 0.73 [95% CI, 0.53 to 0.99]; ARD, 2%; 5 trials). No association was found for several outcomes, including mortality (stillbirth, neonatal, or perinatal), respiratory distress syndrome, hypoglycemia (any or clinical), and hyperbilirubinemia. There were no observed differences for several outcomes in one RCT based on timing of diagnosis, glycemic severity, or Hispanic ethnicity (vs. non-Hispanic White).

Few trials examined longer-term maternal or childhood outcomes. One trial found no association between treatment of GDM and impaired fasting glucose, obesity, metabolic syndrome, or type 2 diabetes mellitus at 5 to 10 years. No study measured the effects of treatment of GDM on quality of life, cardiovascular outcomes, or mortality or major morbidity from type 2 diabetes mellitus.29 For long-term intermediate and health outcomes in children, treatment of mothers for GDM vs. no treatment was not associated with reduced risk of overweight (over 4 to 10 years), obesity (over 5 to 11 years), impaired glucose tolerance (at 9 years), or impaired fasting glucose (over 5 to 11 years). No study measured cardiovascular or neurocognitive outcomes.29 All findings from the four small trials of early treatment were highly imprecise.

Harms of Screening and Treatment

Seven observational studies (n=166,082) looked at harms associated with screening for GDM. Three studies provided data on potential psychosocial harms (i.e., anxiety, depressive symptoms, or both) from screening, receipt of a positive diagnostic test, or receipt of a false-positive result. Three large studies examined hospital experiences related to breastfeeding outcomes in women with GDM and one study examined the likelihood of cesarean delivery as a result of a GDM diagnosis. There was no increase in anxiety/depression with screening or receiving a false-positive result and a small, transient increase in anxiety associated with GDM diagnosis. Diagnosis of GDM may be associated with lower rates of breastfeeding in the first hour after birth, exclusive breastfeeding in the hospital, and neonate’s time in mother’s room, although confounding factors (e.g., breastfeeding intentions, varying hospital policies, and treatment effects) could have affected findings. One study found that GDM diagnosis and labeling may be associated with higher rates of cesarean delivery.29

Harms associated with the treatment of GDM were evaluated in 13 trials (11 RCTs and 2 nonrandomized, controlled trials; n=4,235).29 Treatment at or after 24 weeks of gestation was not associated with an increased risk for severe maternal hypoglycemia, low birthweight, or small for gestational age infants. There was no observed difference of small for gestational age infants based on race/ethnicity or glycemic status. Treatment of GDM was associated with a reduced risk of macrosomia (>4,000 g) (RR, 0.53 [95% CI, 0.41 to 0.68]) but no difference in the risk of total number of cesarean deliveries (RR, 0.95 [95% CI, 0.83 to 1.08]).29 This suggests a small proportion of pregnant persons may undergo cesarean delivery because of GDM diagnosis alone.

How Does Evidence Fit With Biological Understanding?

Gestational diabetes mellitus usually arises after 20 weeks of gestation, when placental hormones with the opposite effect of insulin increase substantially. Pregnant persons with adequate insulin secreting capacity can overcome this insulin resistance of pregnancy by secreting more insulin to maintain normal blood glucose. Pregnant persons who are unable to produce adequate insulin to overcome the increase in insulin resistance seen in pregnancy develop glucose intolerance and GDM.

Screening for GDM is generally recommended between 24 and 28 weeks of pregnancy. Pregnant persons with GDM are at increased risk for maternal and infant complications. Screening for and detecting GDM provides a potential opportunity to control blood glucose (through lifestyle changes, pharmacological interventions, or both) and reduce the risk of macrosomia and LGA infant. In turn, this can prevent associated complications such as primary cesarean delivery, shoulder dystocia, and NICU admissions.

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The USPSTF identified several gaps in the evidence where more research is needed. These include:

  • Studies (specifically RCTs) on the effect of screening for GDM and health outcomes
  • Studies examining the benefits and harms of screening for and treatment of GDM in persons at less than 24 weeks of gestation
  • Greater consistency in both the diagnostic criteria and outcome definitions used in studies
  • More studies that report on maternal health outcomes, especially hypertension and preeclampsia
  • Studies focusing on longer-term outcomes (i.e., obesity, impaired fasting glucose) for both mother and child
  • Studies reporting on the effects of GDM screening on populations defined by race/ethnicity, age, and other relevant socioeconomic factors
  • Studies examining how health outcomes differ by screening strategy (one vs. two step testing and thresholds for GDM, fasting plasma level, and HbA1c concentration)
  • Studies on potential harms of screening and treatment (i.e., anxiety, hospital experience, and cesarean delivery).
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Major guidelines from organizations in the United States generally recommend universal, rather than selective/risk-based screening, at 24 to 28 weeks of gestation. Guidelines differ with respect to the number of tests and the diagnostic criteria applied. The American College of Obstetricians and Gynecologists and the National Institutes for Health recommend screening all pregnant women for GDM using a two-step screening strategy (using either Carpenter and Coustan or NDDG criteria) at 24 to 28 weeks of gestation.1,35 The American Diabetes Association recommends glucose testing for GDM in all asymptomatic pregnant women at 24 to 28 weeks of gestation using either one-step (using IADPSG criteria) or two-step (using Carpenter and Coustan criteria) screening.36 The Endocrine Society recommends universal screening for GDM using the OGTT at 24 to 28 weeks of gestation.37 The American Academy of Family Physicians endorses screening for GDM in asymptomatic pregnant women after 24 weeks of gestation. It also concludes that the evidence is insufficient to assess the balance of benefits and harms of screening for GDM in asymptomatic pregnant women before 24 weeks of gestation.38

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1. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 190 summary: gestational diabetes mellitus. Obstet Gynecol. 2018;131(2):406-408.
2. American Diabetes Association. 2. Classification and diagnosis of diabetes: standards of medical care in diabetes-2020. Diabetes Care. 2020;43(Suppl 1):S14-S31.
3. Metzger BE, Lowe LP, Dyer AR, et al. Hyperglycemia and adverse pregnancy outcomes. N Engl J Med. 2008;358(19):1991-2002.
4. Casagrande SS, Linder B, Cowie CC. Prevalence of gestational diabetes and subsequent type 2 diabetes among U.S. women. Diabetes Res Clin Pract. 2018;141:200-208.
5. DeSisto CL, Kim SY, Sharma AJ. Prevalence estimates of gestational diabetes mellitus in the United States, Pregnancy Risk Assessment Monitoring System (PRAMS), 2007-2010. Prev Chronic Dis. 2014;11:E104.
6. Lavery JA, Friedman AM, Keyes KM, Wright JD, Ananth CV. Gestational diabetes in the United States: temporal changes in prevalence rates between 1979 and 2010. BJOG. 2017;124(5):804-813.
7. Zhou T, Sun D, Li X, et al. Prevalence and trends in gestational diabetes mellitus among women in the United States, 2006–2016. Diabetes. 2018;67(Suppl 1).
8. Brown FM, Wyckoff J. Application of one-step IADPSG versus two-step diagnostic criteria for gestational diabetes in the real world: impact on health services, clinical care, and outcomes. Curr Diabet Rep. 2017;17(10):85.
9. Hartling L, Dryden DM, Guthrie A, et al. Screening and diagnosing gestational diabetes mellitus. Evid Rep Technol Assess (Full Rep). 2012(210):1-327.
10. Hartling L, Dryden DM, Guthrie A, Muise M, Vandermeer B, Donovan L. Diagnostic thresholds for gestational diabetes and their impact on pregnancy outcomes: a systematic review. Diabet Med. 2014;31(3):319-331.
11. Farrar D, Simmonds M, Bryant M, et al. Hyperglycaemia and risk of adverse perinatal outcomes: systematic review and meta-analysis. BMJ. 2016;354:i4694.
12. Lowe WL Jr, Scholtens DM, Lowe LP, et al. Association of gestational diabetes with maternal disorders of glucose metabolism and childhood adiposity. JAMA. 2018;320(10):1005-1016.
13. Savitz DA, Danilack VA, Elston B, Lipkind HS. Pregnancy-induced hypertension and diabetes and the risk of cardiovascular disease, stroke, and diabetes hospitalization in the year following delivery. Am J Epidemiol. 2014;180(1):41-44.
14. Tobias DK, Stuart JJ, Li S, et al. Association of history of gestational diabetes with long-term cardiovascular disease risk in a large prospective cohort of US women. JAMA Intern Med. 2017;177(12):1735-1742.
15. Goueslard K, Cottenet J, Mariet AS, et al. Early cardiovascular events in women with a history of gestational diabetes mellitus. Cardiovasc Diabetol. 2016;15:15.
16. Lowe WL Jr, Scholtens DM, Kuang A, et al. Hyperglycemia and Adverse Pregnancy Outcome Follow-up Study (HAPO FUS): maternal gestational diabetes mellitus and childhood glucose metabolism. Diabetes Care. 2019;42(3):372-380.
17. U.S. Preventive Services Task Force. Procedure Manual. https://uspreventiveservicestaskforce.org/uspstf/procedure-manual. Accessed January 27, 2021.
18. Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Report of the expert committee on the diagnosis and classification of diabetes mellitus. Diabetes Care. 2003;26(Suppl 1):S5-S20.
19. Deputy NP, Kim SY, Conrey EJ, Bullard KM. Prevalence and changes in preexisting diabetes and gestational diabetes among women who had a live birth - United States, 2012-2016. MMWR Morb Mortal Wkly Rep. 2018;67(43):1201-1207.
20. Dennis JA. Birth weight and maternal age among American Indian/Alaska Native mothers: a test of the weathering hypothesis. SSM Popul Health. 2019;7:004-004.
21. Hedderson M, Ehrlich S, Sridhar S, Darbinian J, Moore S, Ferrara A. Racial/ethnic disparities in the prevalence of gestational diabetes mellitus by BMI. Diabetes Care. 2012;35(7):1492-1498.
22. Kim SY, Saraiva C, Curtis M, Wilson HG, Troyan J, Sharma AJ. Fraction of gestational diabetes mellitus attributable to overweight and obesity by race/ethnicity, California, 2007-2009. Am J Public Health. 2013;103(10):e65-e72.
23. Ferrara A. Increasing prevalence of gestational diabetes mellitus: a public health perspective. Diabetes Care. 2007;30(Suppl 2):S141-S146.
24. Naylor CD, Sermer M, Chen E, Farine D. Selective screening for gestational diabetes mellitus. Toronto Trihospital Gestational Diabetes Project Investigators. N Engl J Med. 1997;337(22):1591-1596.
25. National Institute for Health and Care Excellence. Gestational diabetes: risk assessment, testing, diagnosis and management. https://pathways.nice.org.uk/pathways/diabetes-in-pregnancy. Accessed January 27, 2021.
26. Bimson BE, Rosenn BM, Morris SA, Sasso EB, Schwartz RA, Brustman LE. Current trends in the diagnosis and management of gestational diabetes mellitus in the United States. J Matern Fetal Neonatal Med. 2017;30(21):2607-2612.
27. American College of Obstetricians and Gynecologists Committee on Practice Bulletins - Obstetrics. Practice Bulletin No. 180: gestational diabetes mellitus. Obstet Gynecol. 2017;130(1):e17-e37.
28. International Association of Diabetes and Pregnancy Study Groups Consensus Panel, Metzger B, Gabbe S, et al. International Association of Diabetes and Pregnancy Study Groups recommendations on the diagnosis and classification of hyperglycemia in pregnancy. Diabetes Care. 2010;33(3):676-682.
29. Pillay J, Donovan L, Guitard S, et al. Screening for Gestational Diabetes Mellitus: A Systematic Review to Update the 2014 U.S. Preventive Services Task Force Recommendation. Evidence Review No. 204. AHRQ Publication No. 21-05273-EF-1. Rockville, MD: Agency for Healthcare Research and Quality;2021.
30. U.S. Preventive Services Task Force. Screening for abnormal blood glucose and type 2 diabetes mellitus: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2015;163(11):861-868.
31. US Preventive Services Task Force. Behavioral weight loss interventions to prevent obesity-related morbidity and mortality in adults: US Preventive Services Task Force recommendation statement. JAMA. 2018;320(11):1163-1171.
32. U.S. Preventive Services Task Force. Screening for gestational diabetes mellitus: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2014;160(6):414-420.
33. Crowther CA, Hiller JE, Moss JR, McPhee AJ, Jeffries WS, Robinson JS. Effect of treatment of gestational diabetes mellitus on pregnancy outcomes. N Engl J Med. 2005;352(24):2477-2486.
34. Yang X, Tian H, Zhang F, et al. A randomised translational trial of lifestyle intervention using a 3-tier shared care approach on pregnancy outcomes in Chinese women with gestational diabetes mellitus but without diabetes. J Transl Med. 2014;12:290.
35. Vandorsten JP, Dodson WC, Espeland MA, et al. NIH consensus development conference: diagnosing gestational diabetes mellitus. NIH Consens State Sci Statements. 2013;29(1):1-31.
36. American Diabetes Association. 2. Classification and diagnosis of diabetes: standards of medical care in diabetes–2021. Diabetes Care. 2021;44(Suppl 1):S15-S33.
37. Blumer I, Hadar E, Hadden DR, et al. Diabetes and pregnancy: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2013;98(11):4227-4249.
38. American Academy of Family Physicians. Clinical Preventive Service Recommendation: Gestational Diabetes. https://www.aafp.org/family-physician/patient-care/clinical-recommendations/all-clinical-recommendations/diabetes.html. Accessed January 27, 2021.
39. Carpenter MW, Coustan DR. Criteria for screening tests for gestational diabetes. Am J Obstet Gynecol. 1982;144(7):768-773.
40. National Diabetes Data Group. Diabetes in America, 2nd ed. Bethesda, MD: National Institutes of Health; 1995.

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Rationale Assessment
Pregnant Persons at 24 Weeks of Gestation or After Pregnant Persons Before 24 Weeks of Gestation
Detection There is adequate evidence that commonly used screening tests can accurately detect GDM. There is inadequate evidence that commonly used screening tests can accurately detect GDM earlier than 24 weeks of gestation.
Benefits of early detection and intervention and treatment
  • There is inadequate direct evidence that screening for GDM improves health outcomes.
  • There is adequate evidence that treatment of screen-detected GDM can improve maternal and fetal outcomes, including primary (first) cesarean delivery, macrosomia, large for gestational age infant, shoulder dystocia, birth injury, and neonatal intensive care unit admissions.
  • There is inadequate direct evidence that screening for GDM improves health outcomes.
  • There is inadequate evidence that treatment of GDM earlier than 24 weeks gestation can improve maternal and fetal outcomes.
Harms of early detection and intervention and treatment
  • There is adequate evidence that the harms of screening for GDM, such as anxiety, depression, and labeling, are small.
  • There is adequate evidence that the harms of treatment of GDM, such as maternal hypoglycemia and low birthweight, are small.
There is inadequate evidence on the harms of screening for and treatment of GDM earlier than 24 weeks of gestation.
USPSTF Assessment The USPSTF concludes with moderate certainty that screening for and treatment of GDM at 24 weeks of gestation or after has moderate net benefit. Benefits and harms of screening for GDM earlier than 24 weeks of gestation are uncertain, and the balance of benefits and harms cannot be determined.

Abbreviation: GDM=gestational diabetes mellitus.

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  Glucose Load of OGTT Fasting Threshold 1 Hour Threshold 2 Hour Threshold 3 Hour Threshold
Two-Step Screening: An initial screening 50-g OGCT is administered. If the OGCT is positive (≥130–140 mg/dL [7.2–7.8 mmol/L] at 1 hour), then proceed with OGTT. Diagnosis of GDM if two or more thresholds met on OGTT.
Carpenter and Coustan39 100 g 95 mg/dL
5.3 mol/L
180 mg/dL
10.0 mmol/L
155 mg/dL
8.6 mmol/L
140 mg/dL
7.8 mmol/L
National Diabetes Data Group (NDDG)40 100 g 105 mg/dL
5.8 mmol/L
190 mg/dL
10.5 mmol/L
165 mg/dL
9.1 mmol/L
145 mg/dL
8.0 mmol/L
One-Step Screening: Diagnosis of GDM if one or more thresholds met on OGTT.
International Association of Diabetes and Pregnancy Study Group (IADPSG)28 75 g 92 mg/dL
5.1 mmol/L
180 mg/dL
10.0 mmol/L
153 mg/dL
8.5 mmol/L
 

Abbreviations: GDM=gestational diabetes mellitus; OGCT=oral glucose challenge test; OGTT=oral glucose tolerance test.

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