Two‐ vs one‐hour glucose tolerance testing: Predicting prediabetes in adolescent girls with obesity

Background During an oral glucose tolerance test (OGTT), morphological features of the glucose curve (monophasic curve, glucose peak >30 minutes and 1‐hour glucose ≥ 155 mg/dL) maybe associated with higher prediabetes risk, but their reproducibility and predictive ability in adolescents with obesity are unknown. Methods Nondiabetic adolescent girls with obesity underwent a multiple‐sample OGTT at baseline ( n  = 93), 6 weeks ( n  = 83), and 1 year ( n  = 72). Short‐term reproducibility (baseline to 6 weeks) and the predictive ability for prediabetes (baseline to 1 year) for each feature were compared with standard fasting and 2‐hour OGTT diagnostic criteria. Results There was fair/moderate short‐term reproducibility (κ < 0.5) for all morphological features. At 1 year, compared with standard OGTT criteria, the areas under the receiver operating curve (ROC‐AUCs) for glucose peak > 30 minutes, 1 hour ≥155 mg/dL or a combination of the two criteria were comparable (all P  > 0.05), but the monophasic curve had the lowest ROC‐AUC ( P  < 0.001). Conclusions In adolescent girls with obesity, glucose peak > 30 minutes and/or glucose ≥155 mg/dL had similar reproducibility and 1‐year predictive ability for prediabetes compared with standard OGTT criteria. The shortened 1‐hour OGTT may provide diagnostic equivalence for prediabetes risk with the additional advantage of a less time‐consuming risk assessment.