Vitamin D in relation to metabolic risk factors, insulin sensitivity and adiponectin in a young Middle-Eastern population.

OBJECTIVES

Several studies suggest a link between circulating 25-hydroxyvitamin D (25(OH)D) and metabolic risk factors. However, this relation has been mainly studied in elderly and/or obese subjects. In addition, the relation between 25(OH)D and adiponectin is unclear. The purpose of this study is to look at these relations in non-obese young individuals.

DESIGN

We investigated the relation between serum 25(OH)D and adiposity, blood pressure, glucose metabolism, lipid profile, and adiponectin in 381 randomly selected university students (201 males and 180 females, mean age 23.9+/-3.9).

RESULTS

In the overall population, 25(OH)D is significantly inversely correlated with body mass index (BMI), systolic blood pressure (SBP), waist circumference (WC), fasting plasma glucose (FPG), insulin levels, and homeostasis model assessment of insulin resistance (HOMA index) and positively correlated with adiponectin and high density lipoprotein-cholesterol (P<0.01 for all variables). In males, these correlations are still significant for BMI, SBP, WC, and adiponectin (P=0.02, P=0.01, P=0.04 and P=0.01 respectively); also, 25(OH)D is inversely correlated with low density lipoprotein (LDL)-cholesterol (P=0.007). In females, 25(OH)D is only inversely correlated with FPG and HOMA index (P<0.001 and P=0.03 respectively). In multivariate regression analysis models, after adjustment for sex and BMI, 25(OH)D is an independent predictor of FPG and SBP (P=0.032 and P=0.05 respectively) in the overall population, while in males 25(OH)D is a predictor of LDL-cholesterol and SBP independently of BMI (P=0.007 and P=0.035 respectively).

CONCLUSION

In non-obese young subjects, we observe new relationships between 25(OH)D and several metabolic risk factors and adiponectin. Further research is needed to elucidate the gender differences and to look at the relation between 25(OH)D and adiponectin.