One‐hour plasma glucose concentration during the OGTT: what does it tell about β‐cell function relative to insulin sensitivity in overweight/obese children?

Tfayli H, Jung Lee S, Bacha F, Arslanian S. One‐hour plasma glucose concentration during the OGTT: what does it tell about β‐cell function relative to insulin sensitivity in overweight/obese children? Background: In adults 1‐h plasma glucose concentration cut‐point of 155 mg/dL (8.6 mmol/L) during the oral glucose tolerance test (OGTT) is a strong predictor of future diabetes risk. Objective: We tested the hypothesis that a 1‐h glucose concentration ≥155 mg/dL is associated with lower β‐cell function in overweight/obese youth. Research design and methods: One hundred and thirteen diabetes free overweight/obese youth aged 10–20 yr, underwent evaluation of β‐cell function during a 2 h hyperglycemic clamp ∼225 mg/dL (12.5 mmol/L), and insulin sensitivity during a 3 h hyperinsulinemic–euglycemic clamp, and a standard 2 h OGTT. Body composition and abdominal adiposity were determined by DEXA and CT scan. The disposition index (DI) was calculated as the product of first‐phase insulin secretion and insulin sensitivity. Subjects were divided into two categories of 1‐h plasma glucose concentration: <155 mg/dL (n = 69) and ≥155 mg/dL (n = 44). Results: Youth with 1‐h glucose ≥155 mg/dL had lower DI than those with 1‐h glucose <155 mg/dL (295.1 ± 27.4 vs. 498.6 ± 37.7 mg/kg/min, p < 0.001), independent of the glucose tolerance status. In multiple regression models, DI was the strongest contributor to 1‐h glucose concentration explaining ∼21% of its variance. Conclusions: Overweight/obese youth with 1‐h glucose ≥155 mg/dL during the oral glucose tolerance test have a significantly lower β‐cell function relative to insulin sensitivity even within the normal glucose tolerance range. Such youth may be at higher risk of future diabetes.