Background: In cohort and observational studies, it was clear that vitamin D deficiency is associated with insulin resistance and risk of future diabetes. However, randomized controlled trials with vitamin D supplementation for improving glucose tolerance or prevention of type 2 diabetes is still controversial.
Methods: We conducted the Diabetes Prevention on Vitamin D (DPVD) study which was a large, randomized, double-blind, placebo-controlled study to examine whether eldecalcitol, an active form of vitamin D analog, can reduce the risk of type 2 diabetes in patients with impaired glucose tolerance. Participants were randomly assigned to receive eldecalcitol or placebo. The primary endpoint was the incidence of type 2 diabetes and the secondary endpoint was the conversion to normal glucose tolerance. The study duration was 3 years.
Results: The mean follow-up was 2.6 years. A total of 1256 participants were enrolled in the study. 57 of 630 (9.0%) participants in the eldecalcitol and 64 of 626 (10.2%) in the placebo group developed type 2 diabetes (hazard ratio, 0.87; 95% confidence interval, 0.68 to 1.09; p=0.37). In the subgroup participants with vitamin D deficiency (serum 25-hydroxyvitamin D<20 ng/ml), the difference of the incidence of type 2 diabetes between the two groups was greater; however, there was no statistical significance. Two hundred ninety-five of 630 (46.8%) participants in the eldecalcitol and 267 of 626 (42.7%) in the placebo group achieved normal glucose tolerance (hazard ratio, 1.10; 95% confidence interval, 0.93 to 1.31; p=0.45). No serious adverse events related to the intervention were recorded.
Conclusion: Our study showed that treatment with eldecalcitol was not associated with a reduction in the incidence of type 2 diabetes or an increase in the conversion to normal glucose tolerance among patients with impaired glucose tolerance.
T. Kawahara: None.
