Predictive Characteristics of Elevated 1-Hour Glucose Challenge Test Results for Gestational Diabetes

Objective  The objective was to estimate the optimal screen-positive 1-hour 50 g glucose challenge test (GCT) threshold for gestational diabetes (GDM) and predictive characteristics of increasing screen-positive GCT threshold values (135–199 mg/dL) for GDM. Study Design  It is a secondary analysis of a multicenter mild GDM study. At 24 to 30 weeks' gestation, women with elevated GCT (135–199 mg/dL) completed a diagnostic 3-hour oral glucose tolerance test (OGTT). A novel change-point analysis method was used to compare the GDM rates for the adjacent GCT values, delineating categories of changing risk such that values within categories have equal risk for GDM. Positive (PPV) and negative (NPV) predictive values for GDM were computed for increasing GCT cut-offs. Results  In 7,280 women with both GCT (135–199 mg/dL) and OGTT results, 4 GDM risk-equivalent GCT categories were identified with escalations at 144, 158, and 174 mg/dL (all p -values Conclusion  Elevated GCT cut-off values between 135 and 143 mg/dL may carry equivalent GDM risk. No threshold GCT value