The Association Between Serum Vitamin D Status and Cardiometabolic Risk Factors in Extremely Obese Adults: A Cross-Sectional Study.

Background: Vitamin D may play a vital role in glucose and lipid metabolism, but existing studies on this topic are limited and inconsistent. The aim of our study was to undertake an in depth exploration of the relationship between vitamin D and cardiometabolic markers in extremely obese individuals in North China. Methods: In this cross-sectional study, 293 adults aged between 18 and 60 years with BMIs higher than 35 kg/m² were recruited from Beijing, China. Serum 25(OH) D was measured using chemiluminescence, and concentrations of glucose, insulin, and lipids were quantified as well. Multiple linear regression analysis adjusted for potential confounding factors was used to assess independent associations between serum 25(OH) D and lipid profiles. Results: The prevalence of vitamin D deficiency was 81.2% in the extremely obese subjects, and the median serum 25(OH) D concentration was 12.88 ng/mL. Moreover, 25(OH) D levels were significantly negatively associated with the BMI and parathyroid hormone (p < 0.0001). After adjustment for age, sex, BMI, and HOMA-IR, 25(OH) D levels were positively correlated with HDL-c (p < 0.007) and ApoA1 as well (p < 0.001). No significant differences in blood pressure, fasting blood glucose, or HOMA-IR were detected between vitamin D nondeficient (≥ 20 ng/mL) and deficient (< 20 ng/mL) groups. Conclusions: Vitamin D deficiency is highly prevalent in extremely obese individuals in China, exhibiting significant correlations with higher BMI and lower HDL-c/ApoA1. Our findings underscore the importance of vitamin D deficiency as a correlate of cardiovascular risk. Prospective studies and randomized clinical trials are warranted to determine the effect of 25(OH) D on other cardiometabolic parameters.