Ponto de corte para o Modelo Homeostático de Avaliação da Resistência à Insulina associado à síndrome metabólica para adolescentes brasileiros

Abstract

The homeostatic model assessment of insulin resistance (HOMA-IR) index provides an indirect measurement of insulin resistance. However, so far, no HOMA-IR cut-off points have been established for a representative sample of the Brazilian adolescent population. Thus, the present work had as objective to define HOMA-IR cut-off values associated with metabolic syndrome (MS) for Brazilian adolescents. It is a subproject of The Study of Cardiovascular Risks in Adolescents (ERICA), which is a cross-sectional multicenter national school-based study. The ERICA study was performed with adolescents aged between 12 and 17 years enrolled in public and private schools of Brazilian cities with more than 100,000 inhabitants. The sample size proposed in the original project that provided a sample with local, regional and national representativeness was 74 thousand individuals. The students who accepted to participate were interviewed, submitted to the anthropometric evaluation and the systemic arterial pressure. In the morning shift students, blood samples were collected for the determination of total cholesterol, high density lipoprotein, triglycerides, glucose and plasma insulin. The HOMA-IR index and the body mass index by age and sex were calculated. The diagnosis of MS was established according to the International Diabetes Federation criteria. The ROC curve was constructed to identify the optimal cut-off values associated with MS for HOMA-IR by gender and in the total sample population. The percentiles of HOMA-IR and insulin, according to age and sex, were also performed. Complete data (questionnaire responses, blood pressure measurements, anthropometric data and biochemical results) were obtained from 37,815 adolescents. The best cut-off points associated with MS for HOMA-IR in the total population, in female and in male adolescents were 2.80, 2.32 and 2.87, respectively. According to these values, the prevalence of insulin resistance in the total population was 19.1%. The prevalence was 5.3 times higher among obese adolescents compared with normal weight adolescents, and 2.3 times higher in girls than boys. Regarding the distribution of HOMA-IR and insulin, the medians tended to decrease with age in both sexes. These findings may serve as reference points for detection of insulin resistance in adolescents, enabling an early intervention and prevention of chronic diseases.