Background: Diabetes mellitus (DM) is a group of metabolic disorders Characterized by chronic hyperglycaemic condition resulting from defects in insulin secretion, insulin action or both. Type2 Diabetes Mellitus (T2DM) is the predominant form of diabetes and represent 90% of all cases of DM. Studies show that vitamin D (VD) has an important role in modifying the risk of T2DM, especially among insulin resistant diabetic patients. Recently a novel association between insulin resistance and vitamin D deficiency has been proposed. Aim: In the current research we investigate the association between hypovitaminosis D and T2DM. Also we will study the effect of vitamin D supplementation on glycemic status, oxidative stress status and inflammatory markers in T2DM patients. Methods and patients: forty T2DM patients with hypovitaminosis D were assessed for glycemic, inflammatory and antioxidants parameters. After 6 months of VD supplementation for the intervention group of patients (n=20), there was significant improvement in VD level, Homeostatic model assessment of insulin resistance (HOMA - IR), Fasting blood glucose (FBG), glycated haemoglobin (HbAIC), serum insulin, interleukin 6 (IL-6), tumor necrosis factor -α (TNF-α), total antioxidant capacity (TAC) and malondialdehyde (MDA). Conclusion: Vitamin D supplementation has a promising effect on the treatment of Type 2 Diabetes as there is a significant improvement in glycemic , inflammatory and oxidative parameters in Type 2 Diabetes mellitus patients