the effects of vitamin d supplementation on glucose control and insulin resistance in patients with diabetes type 2: a randomized clinical trial study.

vitamin d deficiency is prevalent in diabetes type 2 and this vitamin may be related to insulin action. this randomized controlled trial study was done to evaluate the effect of vitamin d supplementation on glucose control and insulin resistance in patients with diabetes type 2.participants of this randomized clinical trial study consisted of 28 patients with type 2 diabetes who received 100 microgram (4000 iu) vitamin d and 30 diabetic patients who received placebo for 2 months between september 2012 and february 2013. the effect of vitamin d on glucose control was assessed by measuring hba1c and insulin resistance as homa-ir at the baseline and the end of the intervention.the results showed a significant decrease in hba1c (from 7.29 ± 0.22 % to 6.76 ± 0.18 %, p<0.001) and insulin concentration (from 8.24 ± 0.97 μiu/ml to 6.55 ± 0.28 μiu/ml, p=0.048), but a non-significant decrease in homa-ir in vitamin d group. also, hdl-c level increased significantly in both of vitamin d (p=0.046) and placebo groups (p=0.028).it seems that vitamin d supplementation has beneficial effects on glucose homeostasis and can increases insulin sensitivity in diabetic 2 patients.