Association of Waist Circumference and Body Composition Indices with Insulin Resistance in Prepubertal Children with...

Background: Body mass index (BMI) is widely used to assess pediatric obesity but has limitations in distinguishing between fat and muscle mass. This study aimed to investigate the association between various body composition parameters and insulin resistance (IR) and to evaluate their clinical utility in prepubertal children with obesity. Methods: This retrospective cross-sectional study evaluated prepubertal children with obesity. Anthropometric measures and body composition, including percent body fat (PBF) and fat-to-muscle ratio (FMR), were assessed using bioelectrical impedance analysis. IR was defined as a homeostasis model assessment of insulin resistance (HOMA-IR) ≥2.5. Spearman rank correlation, linear regression, and multivariate logistic regression analysis were performed to identify independent associated factors for IR. Results: A total of 147 prepubertal children (61 males, 86 females) were analyzed. The IR group exhibited significantly higher waist circumference SDS (WC_SDS), waist circumference-to-height ratio SDS (WHtR_SDS), and FMR compared to the non-IR group (all p < 0.05). In correlation analysis, HOMA-IR showed significant positive associations with WC_SDS (ρ = 0.39) and FMR (ρ = 0.22). After adjusting for age and sex, WC SDS (odds ratio (OR) = 6.04; 95% CI: 2.47-14.75; p < 0.001), FMR (OR = 4.41; 95% CI: 1.16-16.78; p = 0.030), BMI SDS (OR = 2.31; 95% CI: 1.30-4.10; p = 0.004), and PBF (OR = 1.12; 95% CI: 1.04-1.20; p = 0.004) remained independent risk factors for IR. Conclusions: In prepubertal children with obesity, WC SDS, FMR, BMI SDS and PBF were each significantly associated with IR after adjusting for age and sex. These findings suggest that measures of central adiposity and fat-to-muscle balance, in addition to conventional weight-based indices, are relevant to metabolic risk assessment in this age group.