Vitamin D Insufficiency is Associated with Greater Obesity‐Related Insulin Resistance

Insulin resistance (IR) and vitamin D insufficiency [circulating 25‐hydroxyvitamin D (25OHD) ≤50nmol/L] are associated with obesity (BMI≥30kg/m2). We reported that visceral adipose tissue (VAT) is a negative determinant of plasma 25OHD. Given that vitamin D may play a role in insulin sensitivity the goal of this study is to explore the association between a vitamin D insufficiency/obesity phenotype with IR in healthy adults (N=364). Subjects were assessed for socio‐demographics; anthropometrics; body fat distribution; fasting plasma glucose, insulin, and 25OHD; and the homeostasis model assessment (HOMA) of IR. Subjects were grouped as: vitamin D adequate/no obesity; vitamin D adequate/obesity; vitamin D insufficiency/no obesity; and vitamin D insufficiency/obesity. Data were analyzed by linear regression adjusted for age, sex, ethnicity, smoking, physical activity, season, and VAT. Vitamin D insufficiency/obesity was observed in 20% of subjects and HOMA‐IR was 21% higher [B=0.207; p=0.033] in these subjects than those in the vitamin D adequate/no obesity group. No associations were observed between HOMA‐IR and adequate vitamin D/obesity or vitamin D insufficiency/no obesity groups. These findings suggest that vitamin D insufficiency in subjects with obesity places them at greater risk for IR, even after adjusting for body fat distribution. Vitamin D may play a role in obesity‐related IR.