Nickan Research Institute Journal of Renal Injury Prevention 2345-2781 3 1 2014 03 01 Efficacy of supplementary vitamin D on improvement of glycemic parameters in patients with type 2 diabetes mellitus; a randomized double blind clinical trial 31 34 10.12861/jrip.2014.10 EN Hamid Nasri Saeed Behradmanesh Ahmad Reza Maghsoudi Ali Ahmadi Parto Nasri Mahmoud Rafieian-Kopaei Journal Article 10.12861/jrip.2014.10 Introduction: Studies have revealed the association between vitamin D deficiency and changes in blood glucose and insulin levels as well as sensitivity of the target tissues to insulin. Objective: In this study, we examined the effect of adding vitamin D (cholecalciferol ; 50,000 units) to therapeutic regimen of T2DM patients compared to placebo on regulating the blood glucose and glycemic parameters. Patients and Methods: This study was a double blind clinical trial conducted on 60 type 2 diabetes mellitus (T2DM) patients. Exclusion criteria were taking calcium, vitamin D supplements or any drugs effecting calcium and vitamin D metabolism in the past 6 months. Serum 25-Hydroxy vitamin D [25(OH)D] level was measured with ELISA method. Patients were administered weekly vitamin D supplementation (50000 units) for 12 weeks. Results: There was no significant relation between HbA1c and 25(OH)D level prior the study (p> 0.05). After intervention, 25(OH)D level in interventional group was significantly higher compared to that of control group. HbA1c in male interventional group was significantly less than that of control group (p= 0.0068). Conclusion: Weekly vitamin D supplementation had beneficial effect on glycemic parameters in male type 2 diabetic patients.