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.

Methods: 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 < .0001). Women with GCT >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.

Conclusions: Our results indicate women with GCT >200 mg/dL could be reasonably treated as GDM without requiring additional oral glucose tolerance test for diagnosis.