217 patients (137 female, 80 male) having diabetes type 2 and age between 20 and 60 years old referred to diabetes Arak clinic were recruited. Inclusion criteria: Absence of hepatic, renal, bone disease, Not receiving anticonvulsant drugs, calcium, anticancer drugs and vitamin D. All of them were examined and information on their age, weight, PTH level, vit D level, BMI, renal and hepatic function tests, lipid profile, FBS, insulin, Ca, P, ALP, albumin, job, income, nutrition, and HOMA-IR were collected. Those with vit deficiency were categorised into three groups: mild deficiency: 20-25 ng/ml of 25-hydroxy vitamin D; moderate deficiency: 10-20 ng/ml of 25-hydroxy vitamin D; sever deficiency: 5-10 ng/ml of 25-hydroxy vitamin D. Patients were then given vit D 50000 units daily for 4 weeks. Their FBS and HoMA-IR were measured and compared before and after intervention