Hostility and Adiposity Mediate Disparities in Insulin Resistance among Adolescents and Young Adults

Objective This study explores whether the relationship between lower socioeconomic status and insulin resistance in adolescents is mediated by both physiological and psychological factors associated with increased cardiometabolic risk Study design School-based longitudinal cohort study of 1222 healthy, non-Hispanic black and white teens. Parent education (PE), youth-specific Cook-Medley hostility scale, waist circumference, height, weight, pubertal status, and fasting plasma insulin (FPI) were measured and FPI reassessed 1 year later. Regression analyses utilizing bootstrapping (n = 2000) were used to estimate the direct and indirect effects of PE on FPI and assess the role of hostility and adiposity while adjusting for covariates. Results Lower PE predicted higher FPI (B = -1.52, P =.003), as did hostility (B =.19, P =.002) and adiposity (waist circumference B =.44, P <.001, BMI B =.98, P <.001). The effect of PE on FPI was mediated by both hostility and adiposity. When adiposity and hostility were accounted for, the effect of PE on FPI decreased by 32% (B = -1.04, P =.04); the total indirect estimate was -.485 (95% CI, -.652, -.041). Hostility accounted for 36% of the meditational effect. Conclusions Lower PE influences insulin resistance through adiposity and hostility. Thus, interventions to reduce health disparities associated with insulin resistance should consider both physiological and psychological approaches. (J Pediatr 2010; 157:572-7).