Investigating for Insulin Resistance and Type 2 Diabetes Mellitus in Obese Children

Abstract

The incidence and prevalence of type 2 diabetes mellitus within the childhood period has increased in the worldwide, particularly among obese children. The aim of this study was to investigate impaired glucose tolerance and insulin resistance in obese children. Thirty-six children (18 girls and 18 boys) aged between 7.4 and 17 years with a body mass index (BMI) > 95th percentile and referred to our hospital between 1998 and 2003. Control group consisted of 30 children (13 girls and 17 boys) aged between 7.2 and 17.8 years with a body mass index between 5th and 95th percentile. Fasting and oral glucose tolerance test (OGTT) 120th min serum glucose and insulin levels were measured. The glucose results were characterized according to the World Health Organizations criteria. Insulin resistance (IR) was defined by homeostasis model assessment (HOMA) as IRHOMA. Fasting glucose levels were in normal limits in all obese and control subjects. OGTT revealed that 9 of 36 obese children (25 %) had diagnosed impaired glucose tolerance and 2 children (6%) diabetes mellitus. Plasma glucose levels in OGTT were in normal limits in all control subjects. IRHOMA revealed insulin resistance in 17 of 36 obese children (47%) and significantly correlated puberty (r=0.418, p=0.0217), BMI (r=0.507, p=0.002), age (r=0.513, p=0.001), and insulin level at 120th min of OGTT (r=0.821, p<0.001). Overall mean IRHOMA in obese and control subjects were 4,1 ± 1.0 and 1,5 ± 0.9 , respectively. The difference of mean IRHOMA levels between obese and control subjects was significantly different (p<0,001). IRHOMA levels of 5 control subjects (16%) were above the level of cut-off point (2,5), however OGTT were normal in these subjects. In conclusion, the childhood obesity is one of the important risk factors for the early beginning of type 2 diabetes mellitus. An OGTT is more sensitive at identifying impaired glucose tolerance or diabetes mellitus than fasting glucose alone. Body-mass index (BMI) was strongest predictor of fasting and glucose stimulated insulin levels.