Markedly different rates of incident insulin treatment based on universal gestational diabetes mellitus screening in a diverse HMO population

Objective We sought to evaluate population gestational diabetes mellitus (GDM) screening results and risk for incident insulin treatment. Study Design Among 64,687 pregnant women universally screened for GDM from 1995 through 2010 in 2 regions of a large US health plan, we stratified women requiring insulin treatment during their pregnancy by GDM screening results (50-g glucose challenge test [GCT]), followed by a 3-hour, 100-g oral glucose tolerance test if GCT was positive. Women with GCT >200 mg/dL were evaluated separately. Results Overall, 2% of all pregnant women required insulin treatment, ranging from 0.1% (normal GCT) to 49.9% (GCT >200 mg/dL; P for trend 200 mg/dL had a much higher rate of insulin treatment than women with GDM (odds ratio, 3.7; 95% confidence interval, 3.1–4.4). Risk factors for higher insulin treatment rates with GDM or GCT >200 mg/dL included obesity, race/ethnicity, and diagnosed ≤16 weeks' gestation. Conclusion Our results indicate women with GCT >200 mg/dL could be reasonably treated as GDM without requiring additional oral glucose tolerance test for diagnosis.