The association between hepatic steatosis, vitamin D status, and insulin resistance in adolescents with obesity

Introduction: Epidemiological studies suggest an inverse relationship between circulating 25-hydroxy-vitamin D [25(OH)D] levels and insulin resistance (IR), yet interventional studies have yielded inconsistent findings. This study examined the relationship between changes in vitamin D status and markers of IR in adolescents, with a focus on the modifying effect of liver fat. Methods: A post-hoc analysis was performed using data from 44 adolescents participating in a 6-month observational study evaluating biomarkers of hepatosteatosis. Participants were categorized into two groups based on vitamin D status at the end of the observation period: those whose vitamin D levels increased or remained sufficient (VDI, n = 22) and those whose levels decreased or remained insufficient/deficient (VDD, n = 22). Liver fat percentage was measured using magnetic resonance imaging (MRI) fat-fraction, and IR was assessed using the updated Homeostatic Model Assessment for Insulin Resistance (HOMA2-IR) and the triglyceride-to-high-density lipoprotein cholesterol ratio (TG/HDL). Results: Across the cohort, liver fat was positively associated with HOMA2-IR (β = 0.08, p = 0.023). The association between changes in vitamin D status and HOMA2-IR trajectories was modified by liver fat but only in Hispanic adolescents (β = −0.18, p