Diabetes mellitus can damage the eyes, kidneys, nerves and heart. Microvascular and macrovascular disorders are the leading causes of morbidity and mortality in diabetic patients. Hyperglycemia can increase the indicators of lipid peroxidation and oxidative stress in which free radicals have the main role in the pathogenesis of these complications. Therefore, antioxidants which combat oxidative stress should be able to prevent and repair free radicals induced damages. Although free radicals contribute to kidney damage, atherosclerosis, diabetes, heart disease, nephrotoxicity and hepatotoxicity; however, clinical trials do not uniquely confirm a substantial impact on diabetic damage. It seems that antioxidants in vegetables, fruits and grains help preventing diabetes complications; however, there is little evidence that taking single antioxidants such as vitamin E or vitamin C protect these complications. The findings about combination antioxidants are also complicated and not entirely clear. In this review paper we tried to present the role of oxidative stress on micro-vascular complications of type 2 diabetes mellitus. Other objective of this paper is to review the new findings about the role of various antioxidants on prevention and treatment of diabetes mellitus as well as its complications including retinopathy, nephropathy and neuropathy.