Distribution of fasting plasma insulin, free fatty acids, and glucose concentrations and of homeostasis model assessment of insulin resistance in a representative sample of Quebec children and adolescents

Background: Plasma fasting insulin and the homeostasis model assessment of insulin resistance (HOMA-IR) are markers of IR, which, at least in part, mediates the relation of obesity to increased cardiovascular risk. Increased free fatty acids (FFAs) may be involved in the pathogenesis of IR. Our objectives were to describe the distributions of fasting plasma insulin, glucose, and FFAs and HOMA-IR in youth and to assess the relationship between FFAs and markers of IR. Methods: Fasting plasma insulin, glucose, and FFAs were measured in a representative sample of Quebec youth comprising 2244 individuals 9, 13, and 16 years of age. Results: In all age and sex groups, glucose exhibited remarkably tight distributions (median CV, 7.1%) in contrast to insulin, HOMA-IR, and FFAs (median CVs, 52%, 54% and 45%, respectively). For every percentile examined, 9-year-olds had lower insulin concentrations and HOMA-IR values than 13- and 16-year-olds. We observed strong correlations between insulin concentrations and HOMA-IR values, as well as close similarity in their rankings of individuals. The mean concentrations of glucose were higher in our population than in other Caucasian pediatric populations. No positive correlations were detected between FFAs and markers of IR. Conclusions: We report some of the first data on the distributions of fasting plasma insulin, HOMA-IR, and FFAs from a representative sample of youth. HOMA-IR does not appear more informative than fasting insulin as a marker of IR. Our findings on higher mean glucose concentrations in this population require confirmation in other representative samples of youth to assess whether the North American distribution of glucose concentrations is shifting positively. (C) 2003 American Association for Clinical Chemistry.