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.
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