Insulin resistance in Brazilian adolescent girls: association with overweight and metabolic disorders.

We assessed the association between insulin resistance, overweight and metabolic disorders in a probabilistic sample of 388, 12-19-year-old girls from public schools in Niterói, Rio de Janeiro State, Brazil. Insulin resistance was determined using Homeostatic Model Assessment-Insulin Resistance (HOMA-IR). Overweight and obesity were defined by the sex- and age-specific body mass index cut-offs recommended by the International Obesity Task Force. Metabolic syndrome (MS) was identified by the presence of at least three of the following factors: fasting glucose >or=100mg/dL, triglycerides >130 mg/dL, LDL-C >or=110 mg/dL, HDL-C <35 mg/dL and overweight. The combined prevalence of obesity (2.9%) and overweight was 14.2%. The average HOMA-IR level was 2.24 (95% confidence interval=1.40-3.10) in the overweight group and 1.91 (95% CI=1.32-2.50) in the non-overweight one, and MS prevalence was 20 times higher in the first group (21.4 and 0.1%). MS prevalence in the overweight group was 6.3 times higher in adolescents above the 66th percentile of HOMA-IR (55.9%) than those under the 33rd percentile (8.9%). Brazilian overweight girls with higher insulin resistance had high risk of developing MS. Therefore, prevention should occur at an early age to impair the evolution of this process.