Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 43 12 2014 12 15 1651 6 Esmaeil Yousefi Rad Dept. of Cellular and Molecular Nutrition, School of Nutritional Sciences And Dietetics, Tehran University of Medical Sciences, Tehran, Iran. Mahmoud Djalali Dept. of Cellular and Molecular Nutrition, School of Nutritional Sciences And Dietetics, Tehran University of Medical Sciences, Tehran, Iran. Fariba Koohdani Dept. of Cellular and Molecular Nutrition, School of Nutritional Sciences And Dietetics, Tehran University of Medical Sciences, Tehran, Iran. Ali Akbar Saboor-Yaraghi Dept. of Cellular and Molecular Nutrition, School of Nutritional Sciences And Dietetics, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Reza Eshraghian Dept. of Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Hassan Javanbakht Dept. of Cellular and Molecular Nutrition, School of Nutritional Sciences And Dietetics, Tehran University of Medical Sciences, Tehran, Iran. Somayeh Saboori Dept. of Cellular and Molecular Nutrition, School of Nutritional Sciences And Dietetics, Tehran University of Medical Sciences, Tehran, Iran. Mahnaz Zarei Dept. of Cellular and Molecular Nutrition, School of Nutritional Sciences And Dietetics, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Javad Hosseinzadeh-Attar Dept. of Clinical Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran. 2015 10 15 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. https://ijph.tums.ac.ir/index.php/ijph/article/view/3760 https://ijph.tums.ac.ir/index.php/ijph/article/download/3760/3423