Higher serum levels of vitamin D are associated with lower blood glucose levels

Objective: Vitamin D plays an important role in bone metabolism. There is now evidence that a higher serum level of 25-hydroxyvitamin D (25[OH] D) is associated with a lower risk of developing type 2 diabetes mellitus, because it provides better glycemic control, possibly by promoting greater insulin sensitivity, and also by improving pancreatic beta cell function. The objective of the present study was to evaluate the possible association between 25(OH) D sufficiency and glycemia. Methods: This was a cross-sectional study involving 680 women, 35 to 74 years of age, selected through systematic sampling. From each participant, fasting blood samples were collected for the determination of 25(OH) D and glucose levels. Results: The mean fasting blood glucose level was 105 mg/dL (range 26-401 mg/dL). Fasting serum levels of 25(OH) D were <30 ng/mL in 65.4% of the participants and <20 ng/mL in 25.6%. A serum 25(OH) D level < 30 ng/mL was positively associated with a blood glucose level >= 100 mg/dL (odds ratio [OR] 1.29, 95% confidence interval [CI] 1.05-1.57), as was a serum 25(OH) D level < 20 ng/mL (OR 1.25, 95% CI 1.04-1.50). Conclusions: Lower serum 25(OH) D concentrations appear to be associated with a high blood glucose levels.