Correlation Between the First Trimester Two-Hour Postprandial Blood Glucose Greater Than 110 mg/dL for the Prediction of Gestational Diabetes Mellitus

Aim: To determine the correlation between first-trimester two-hour postprandial blood glucose (PPBG) > 110 mg/dL for predicting gestational diabetes mellitus (GDM). Methods: This prospective cohort study enrolled 200 women between 8 and 10 weeks of gestation from February 2022 to February 2024. All recruited pregnant women underwent testing for two-hour PPBS at 8-10 weeks and were followed up till delivery. GDM screening was done during 14-16, 24-28, and 32-34 weeks of gestation. Results: Amongst women having PPBS > 110 mg/dL, 95.9% developed GDM, while in the group with PPBS < 110 mg/dL, only 4% developed GDM. In the PPBS > 110 mg/dL group, a significantly higher number of women were in the older age group (p < 0.049), had a higher BMI (p < 0.001), a family history of diabetes (p < 0.001), and previous history of abortion (p < 0.001). Women with PPBS > 110 mg/dL had significantly higher rates of cesarean section (p < 0.01), preterm delivery (p < 0.001), and macrosomia (p < 0.001). A positive correlation (r = 0.677; p < 0.001) was observed between first trimester two-hour PPBS and cord blood glucose levels. Similarly, a positive correlation (r = 0.465; p < 0.001) was present between insulin levels measured during the first trimester with cord blood insulin. The area under the curve (AUC) for PPBS was 0.969 (p < 0.001) with 95% CI: 0.933-0.988. PPBS > 110 mg/dL has a sensitivity of 95.9%, specificity of 95.6%, positive predictive value (PPV) of 95.9%, negative predictive value (NPV) of 95.7%, and diagnostic accuracy of 95.77% to predict GDM. Conclusion: PPBS > 110 mg/dL at two hours exhibits high levels of diagnostic accuracy for the prediction of GDM and is associated with adverse fetomaternal outcomes. PPBG is a superior, physiologic, and low-cost option compared to HbA1c for early prediction of GDM and can also be performed as a simple point-of-care test with a glucometer at home or in the periphery by healthcare workers (HCW) and in wellness centers.