Contribution of insulin resistance to reduced antioxidant enzymes and vitamins in nonobese Korean children

Background: The prevalence of insulin resistance has been reported in nonobese, nondiabetic healthy individuals. We examined the relationship between insulin resistance and the reduced antioxidant systems of plasma lipid soluble vitamins and antioxidant enzymes in erythrocytes and to determine the contributing factors to the antioxidant systems in nonobese children. Methods: We measured blood lipid profiles, glucose, insulin concentrations, plasma antioxidant vitamins and erythrocytic antioxidant enzyme activities of 103 Korean children in the absence of obesity. Insulin resistance was estimated by homeostasis model assessment of insulin resistance (HOMA-IR). Results: A significant inverse relationships between HOMA-IR and lipid corrected β-carotene (r = - 0.233, p < 0.05), α-tocopherol (r = - 0.370, p < 0.0001) were observed. In addition, increased HOMA-IR was significantly related to the decreased activities of superoxide dismutase (r = - 0.226, p < 0.05) and catalase (r = - 0.261, p < 0.05). Stepwise multiple linear regression analyses showed that HOMA-IR was the independent factor to determine the antioxidant status such as plasma α-tocopherol (β = - 0.379, p < 0.0001), β-carotene (β = - 0.243, p < 0.05), SOD (β = - 0.230, p < 0.05), and catalase activity (β = - 0.255, p < 0.05) after adjusting percent ideal body weight, waist circumference, gender, blood lipids and leptin levels in nonobese children. Conclusion: The reduced antioxidant status in insulin resistance state even in nonobese children suggests the importance of early nutritional intervention with features of insulin resistance.