Insulin Sensitivity and Beta Cell Function in Obese Korean Children and Adolescents with Normal Glucose Tolerance

Chung, Sochung; Kim, Kyo Sun; Choi, In Kyung; Kim, Duk Hee

Abstract

PURPOSE
Obesity and insulin resistance are well known risk factors of type 2 diabetes. Impaired fasting glucose and impaired glucose tolerance (IGT) are called prediabetes and considered as a spectrum of disease and the insulin secretory function and insulin sensitivity are an emerging important issues. The aim of this study was to investigate the beta cell function and insulin sensitivity in Korean obese children who have normal glucose tolerance (NGT).
METHODS
The data from two hundred fifty children and adolescents (M/F 165/85, age 12.0 +/- 2.7) were included. Fasting glucose, insulin, total cholesterol, triglyceride, LDL-cholesterol, HDL-choldesterol and oral glucose tolerance test (OGTT) results were analyzed. In this study, insulinogenic index (IGI) and whole body insulin sensitivity index (WBISI) were calculated from oral glucose tolerance test as markers of insulin secretory function and insulin sensitivity. Subjects were divided into 4 groups by glucose level in 120min (Glu120m) quartiles. Hyperbolic feedback curves were drawn with IGI and WBISI.
RESULTS
1) Height, weight, age, sex and BMI were not significantly different among 4 groups. 2) Fasting glucose levels among 4 groups were not significantly different. 3) HOMA-IR was significantly different according to Glu120m. 4) WBISI was significantly decreased according to Glu120m. 5) Leftward shift toward IGT in the feedback curve was significant in higher Glu120m groups.
CONCLUSION
Obese children with high normal levels in oral glucose tolerance test may have a gradual deterioration in glucose stimulated insulin response and have an increased risk of IGT and diabetes. More mechanistic studies for the transition from NGT to IGT and ultimately diabetes should be followed.