Evaluation of insulin resistance in children and adolescent with moderate and severe obesity.

The global increase of obesity in children and adolescents is the main risk factor associated with development of insulin resistance and type 2 diabetes mellitus. Several indices have been published to quantify insulin sensitivity from data obtained by the oral glucose tolerance test (OGTT).The aim of our study was to evaluate the influence of body composition on different indices of insulin sensitivity (ISI) in obese children and adolescents.A total of 292 subjects (161 boys and 131 girls aged 10.4±2.66 years; BMI 29.6±4.32 kg/m2) underwent a standard OGTT. The patients were divided into groups with moderate obesity (Group A = BMI SDS between 2 and 2.5) and severe obesity (Group B = BMI SDS > 2.5). ISI were calculated from plasma glucose and insulin concentrations using HOMA-IR, QUICKI, Cederholm, Matsuda, and Stumvoll.There was a significant (p<0.05) negative correlation between QUICKI, ISI Cederholm, ISI Matsuda, ISI Stumvoll and BMI SDS (r = -0.129, r = -0.128, r = -0.136, and r = -0.153, respectively). No correlation was demonstrated between BMI SDS and HOMA-IR. The ISI were all significantly different between Group A and Group B. In the Group B the ISI QUICKI, Cederholm, Matsuda, and Stumvoll were significantly lower while HOMA-IR resulted higher (Table 1).In our study indexes of insulin sensitivity derived from OGTT correlate strongly with BMI SDS and were significantly impaired in severe obesity. Our data confirm that already in childhood overweight is one of the most important factor for the development of insulin resistance. However, further studies are needed to establish appropriate cut-off values to use for clinical practice.