Objective: To determine the presence of insulin resistance (IR) in a group of overweight and obese adolescents. Materials and Methods: One hundred 10 to 28 year-old children were studied, (77% females); 67% were overweight and the remaining obese. Overweight and obesity were determined by Must et al. criteria: overweight between 85 and 95 percentile and obesity overt the 95 percentile. Glycemia and basal insulin were determined in serum obtained by vein puncture. IR was determined by HOMA’s index considering Keskin diagnosis value of 3,1. Results: There was no biochemical statistical difference between the overweight and obesity groups; 14% showed IR, 16,2% in the obese children and 12,3% in those overweight. Average insulin and HOMA in obese children with IR were 315 uUl/mL and 7, respectively. The insulin and HOMA difference between those with and without IR was statistically signifi...