Are glucose and insulin levels at all time points during OGTT a reliable marker of diabetes mellitus risk in pediatric obesity?

Purpose Childhood overweight and obesity associated with insulin resistance and metabolic syndrome represent the new global pandemic and the main causative factors for dysglycemia, prediabetes, and Type 2 Diabetes Mellitus (T2DM). Predictors, such as HOMA-IR, HOMA-β%, and QUICKI lack specific reference values in children. OGTT is a gold standard for glycometabolic assessment. Recently, a glycemic level higher than 155 mg/dl at + 60′ after glucose ingestion has been defined as a risk factor for T2DM in obese adolescents. We aim to analyze and correlate fasting insulin-resistance markers with OGTT results in overweight/obese children and adolescents. Methods We retrospectively evaluated glucose and insulin values during a 2-h OGTT every 30 min in 236 overweight/obese patients. Glucose values and insulin sum during OGTT were compared to glycometabolic indexes and different cut-off values for insulin sum. Results A 1-h glucose > 155 mg/dl and insulin sum > 535 microU/ml at all times during OGTT are the best predictors of diabetes risk in obese youths. A1-h glucose > 155 mg/dl is significantly associated with HbA1c > 5.7%, while no association was observed between HbA1c > 5.7% and glucose levels at baseline and 2 h. The ability of the standardized HOMA-IR to predict the prediabetes status is clearly lower than the total insulin sum at OGTT. Conclusion Our study demonstrates that also 1-h post-OGTT glucose, together with HbA1c, is an effective diabetes predictor.