Background & objectives: There are growing evidences about relationship between vitamin D metabolism and occurrence of diabetes mellitus. Vitamin D has a role in secretion and possibly the action of insulin and modulates lipolysis and might therefore contribute to the development of cardiovascular diseases. This study was aimed to evaluate whether serum vitamin D3 level in patients with diabetes is lower than that in non-diabetics and if its level has any relation to indices of metabolic syndrome.

 Methods: Sixty nine subjects were enrolled in this case-control study (23 diabetic patients with good control of blood sugar, 23 poor control diabetic patients and 23 healthy subjects as control group). Serum 25(OH) D3, Fasting Blood Sugar (FBS), (2 hour postprandial blood sugar) BS 2hpp, triglyceride (TG), total cholesterol, HDL and HbA1C were measured. We also measured blood pressure, body weight, height and abdomen circumference for individuals. The data were analyzed by Anova, Chi-square and Pearson correlation.

 Results: Serum levels of Vitamin D3 were significantly lower in diabetics compared to non diabetics. (36/5±16/6 v.s. 56/6±19/1 nmol/lit, p<0/001). There was no statistical difference between the group with good control diabetes and poor control diabetes. There was no significant correlation between low serum vitamin D and metabolic syndrome parameters. These findings suggest the need for ongoing evaluation of possible protective role of vitamin D3 supplement in the development of diabetes.

 Conclusions: Based on our results vitamin D deficiency is prominent in patients with diabetes. It appears the vitamin D level should be monitored in diabetic patients.