Context: Gestational diabetes mellitus (GDM) is defined as any degree of hyperglycemia with first recognition during pregnancy. The optimal time to screen for GDM that would maximize the yield and benefits remains unclear.
Objective: Our objective was to appraise the evidence regarding screening for GDM (accuracy, correlation with adverse outcomes, and harms).
Data sources: We searched Ovid Medline, OVID EMBASE, OVID Cochrane Library, Web of Science, Scopus, PsycInfo, and CINAHL through May 2011.
Study selection: We included randomized controlled trials and observational studies that enrolled pregnant woman who were evaluated using different GDM screening tests.
Data extraction: Two reviewers working independently abstracted the data.
Results: We did not find any randomized controlled trials of GDM screening that measured feto-maternal outcomes. A 1-hour 50-g glucose challenge test with a cutoff point at 140 mg/dL was the most commonly used screening method. The results of this test were statistically associated with feto-maternal outcomes (P < .001), even though only 11% of individuals with a positive test (according to Carpenter and Coustan criteria) developed GDM. Positive Carpenter and Coustan criteria were associated with macrosomia (odds ratio [OR] = 2.4, 95% confidence interval [CI] = 1.9-3.1, P < .001) and gestational hypertension (OR = 1.7, CI = 1.3-2.1, P < .001). Positive National Diabetes Data Group criteria were also associated with macrosomia (OR = 3.2, CI = 2.3-4.4, P < .001) and gestational hypertension (OR = 2.1, CI = 1.6-2.8, P < .001).
Conclusions: Indirect evidence supports the use of contemporary screening tests for GDM to identify pregnancies at increased risk of adverse feto-maternal outcomes. It also suggests that use of these tests will place some women under unnecessary treatment for GDM.