Longitudinal analyses among overweight, insulin resistance, and cardiovascular risk factors in children.

OBJECTIVE: It has been questioned whether insulin resistance or obesity is the central abnormality contributing to the cardiovascular risk factors dyslipidemia and hypertension in obesity. RESEARCH METHODS AND PROCEDURES: We studied weight status [SD score (SDS)-BMI], lipids (triglycerides, low-density lipoprotein- and high-density lipoprotein-cholesterol), blood pressure, and insulin resistance index [as homeostasis model assessment (HOMA) model] over a 1-year period in 229 obese white children (median age 12 years).
RESULTS: Any degree of decrease in HOMA was associated with significant decreases in triglycerides (p < 0.001), systolic blood pressure (p < 0.001), and diastolic blood pressure (p < 0.001), whereas the children with different changes in HOMA did not differ significantly in their weight changes. Only the children in the highest quartile of weight reduction (decrease in SDS-BMI > 0.5) demonstrated a significant decrease in systolic blood pressure (p < 0.001), diastolic blood pressure (p < 0.001), and triglycerides (p = 0.012), and an increase in high-density lipoprotein-cholesterol (p = 0.023), whereas with a lower degree of weight loss, there were no significant changes in cardiovascular risk factors. In contrast with a lower degree of weight loss, a reduction of >0.5 SDS-BMI was associated with a significant decrease in HOMA (p < 0.001). DISCUSSION: Because blood pressure and triglycerides decreased with any degree of decrease in HOMA, independently of changes in weight status, these findings support the hypothesis that insulin resistance is the central abnormality contributing to these cardiovascular risk factors. Therefore, improving insulin resistance seems more important than reducing overweight to prevent or treat hypertension and dyslipidemia in obese children.