Metabolic effects of supplementation with vitamin D in type 2 diabetic patients with vitamin D deficiency

AimEpidemiological studies suggest that vitamin D status influences type 2 diabetes mellitus. We investigate the metabolic effects of vitamin D.Material and methodsWe studied consecutive type 2 diabetic patients without insulin therapy with vitamin D deficiency (serum 25-hydroxyvitamin D (25(OH)D) lower than 20 ng/ml). They were treated with 16,000 IU of calcifediol orally once a week for a minimum of 8 weeks.ResultsTwenty eight patients were treated for a mean time of 84.1 days (range 56 to 120 days). All patients achieved serum levels of 25(OH)D higher than 20 ng/ml. There was a significant reduction in fasting glucose (145.6 ± 35.5 vs. 131.7 ± 30.4 mg/dl, p < 0.001). There were small non-significant reductions in HbA1c, fasting insulin and Homeostasis Model Assesment (HOMA)-insulin resistance (IR). There were small non-significant increases in HOMA-insulin sensitivity (S) and HOMA-beta cell function (B) and a small significant increase in Quantitative Insulin Sensitivity Check Index (QUICKI).ConclusionsCorrection of vitamin D deficiency in type 2 diabetic patients decreases fasting glucose. Our results do not rule out improvements in metabolic control, insulin-resistance and function of the beta cell.