EFFECT OF VITAMIN D SUPPLEMENTATION ON IMPROVING VITAMIN D LEVELS AND INSULIN RESISTANCE IN VITAMIN D INSUFFICIENT OR DEFFICIENT TYPE2 DIABETICS

Vitamin D deficiency is associated with impaired insulin secretion, glucose intolerance and type 2 diabetes. This study was conducted to investigate the effects of supplementation with 50,000 IU vitamin D on improving serum vitamin D levels and insulin resistance in vitamin D insufficient or deficient type 2 diabetic patients. In this double blind randomized clinical trial, 81 type 2 diabetic patients with vitamin D levels between 10-30 ng/ml were randomly assigned to intervention (50,000 IU vitamin D3 once a week) and control (placebo once a week) groups according to gender. The study duration was 8 weeks. At the beginning and the end of study, blood samples were collected after 12 hours overnight fasting and fasting serum glucose, insulin and 25-hydroxyvitamin D were measured. Insulin resistance was obtained by HOMA-IR calculation. After 8 weeks supplementation with vitamin D, 25-hydroxyvitamin D level was significantly increased and reached to normal levels in the intervention group. Fasting serum glucose and insulin concentrations and HOMA-IR were significantly decreased in the vitamin D group, but there were no significant changes in the placebo group. Supplementation with 50,000 IU vitamin D for 8 weeks compared to placebo can improve inadequate levels of vitamin D and glycemic indicators in vitamin D insufficient or deficient type 2 diabetic patients.