The impending epidemic: insulin resistance syndrome (IRS) in a representative sample of youth in Quebec, Canada.
Background: Although its prevalence is increasing in adults, there are no data available on precursors of type 2 diabetes, particularly IRS, from representative samples of children in North America. Methods: The Quebec Youth Heart Survey was designed to study the behavioral, biological and genetic correlates of CVD risk factors in a representative probability sample of Quebec youth surveyed with an age-specific questionnaire, standardized clinical measurements and a blood draw during Winter 1999. We studied the correlates of IRS among 735, 773 and 842 individuals aged 9, 13 and 16 years respectively (79.6% French-Canadians). Response rates were 80% for questionnaire and clinical measures and 58.4% for blood draw. Those who declined blood draw were not significantly different for gender, blood pressure (BP), weight, smoking status, urban or rural residence or parental income or education. All biochemical measures were CDC-standardized. Results: In all age-sex categories, HDL-C levels decreased significantly across insulin quartiles while triglycerides (TG), glucose, BMI, tricipital and subscapular skinfolds and BP increased (all p < 0.01). In contrast, no consistent association was observed between insulin quartiles and total cholesterol, LDL-C and apoB. In all age-sex categories, the number of other CVD risk factors (glucose ≥ 6.1 mmol/L, BMI ≥ 85th percentile, systolic BP ≥ 90th percentile, and dyslipidemia (upper quartile for TG and lower quartile for HDL-C) increased significantly across insulin quartiles (all p < 0.001). The prevalence of IRS (defined as 3 or more of hyperinsulinemia (upper quartile) or other CVD risk factors listed above) was as follows: 5.2% and 5.1% of 9-year old boys and girls, 6.9% and 6.7% of 13-year old boys and girls, 9.0% and 5.8% of 16-year old boys and girls, respectively. The prevelence of IRS was similar in French-Canadians and those of other ethnic origins. Conclusion: IRS is highly prevalent in youth, even among children as young as 9 years old and is associated with an atherogenic profile which, if it persists in adulthood, could be associated with a substantial public health burden in the near future.