Incidence of overt diabetes in pregnancy among women with 50-g glucose challenge test ≥ 200 mg/dL

Objectives: To determine the incidence of overt diabetes in pregnancy (ODIP) among women with 50-g GCT results ≥ 200 mg/dL and compare characteristics and pregnancy outcomes between women with and without gestational diabetes (GDM). Methods: A retrospective cohort study was conducted in 212 pregnant women whose 50-g GCT results ≥ 200 mg/dL. ODIP was diagnosed from 75-g OGTT if fasting plasma glucose ≥ 126 and/or 2-h plasma glucose ≥ 200 mg/dL. Various characteristics and pregnancy outcomes were compared between ODIP and those with and without GDM. Results: Incidence of ODIP was 1.9% of all pregnant women and 23.6% of women with 50-g GCT ≥ 200 mg/dL. Women with ODIP and GDM were more likely to be overweight or obese than those without GDM (52%, 39.6%, and 18.2%, p < 0.001). Women with ODIP had significantly higher 50-g GCT results, lower gestational weight gain, and were less likely to deliver vaginally. Insulin therapy was significantly more common in women with ODIP compared to GDM (70.2% vs. 15.4%, p < 0.001). Rates of LGA, macrosomia, and other neonatal outcomes were comparable. BMI ≥ 25 kg/m² and 50-g GCT ≥ 240 mg/dL independently increased the risk of any abnormal glucose tolerance [adjusted OR 3.22 (95% CI 1.55–6.70) and 2.28 (95% CI 1.14–4.58)] and ODIP [adjusted OR 9.43 (95% CI 2.15–41.38) and 6.36 (95% CI 2.85–14.18)], respectively. Conclusion: Incidence of ODIP was 23.6% of women with 50-g GCT ≥ 200 mg/dL. BMI ≥ 25 kg/m² and 50-g GCT ≥ 240 mg/dL independently increased the risk of GDM and ODIP. Neonatal complications were comparable between ODIP and those with and without GDM.