Insulin resistance and vigorous physical activity mediates the relationship between waist circumference and metabolic syndrome in Korean children

Background: Little is known about how physical activity (PA) and insulin resistance (IR) influence the impact of obesity on metabolic syndrome in pediatric populations. Objectives: This cross-sectional observational study aimed to investigate the mediating effects of PA and IR on the relationship between waist circumference (WC) and continuous metabolic syndrome (cMetS) risk scores in children. Methods: A total of 1008 children aged 7–12 years (535 girls and 473 boys) were recruited from our local elementary schools. PA, body mass index (BMI), WC, and percent body fat were measured. cMetS risk scores were calculated by summing the standardized residuals for mean arterial pressure, triglycerides, fasting blood glucose, and high-density lipoprotein cholesterol. Results: Mediation analysis showed a significant indirect effect of WC on cMetS scores through insulin (β= 0.270, 95 % confidence interval [CI = 0.234–0.306) and vigorous PA (β= 0.007, 95 % CI = 0.001–0.015). The direct effect of WC on cMet scores in the presence of the two mediators was significant (β= 0.193, 95 % CI = 0.040–0.066). Conclusion: Our study findings suggest that while WC is the primary determinant of cMetS scores, fasting insulin and vigorous PA partially mediate the association between the two parameters in this study population.