Resveratrol, one of the phytochemicals with anti-oxidant activity, has a high potential in treatment of type 2 diabetes. The aim of this study is to investigate the effect of resveratrol on plasma and peripheral mono-nuclear cells (PBMCs) oxidative stress of the diabetic patients in a double-blind randomized clinical trial. Sixty patients with type 2 diabetes were divided into two groups randomly (30, having resveratrol, 500 mg, twice daily, morning and evening for 60 days). The 2nd group (30 patients) receives the same amount of the placebo. All patients will receive routine medication for diabetes during the study. The lack of life-threatening diseases such as cancer, infectious diseases, cardiovascular and liver diseases are of the inclusion criteria for this study. At the first and the end of the study, blood sample are taken to measure the levels of glucose, HbA1c, lipid profile, plasma oxidative stress markers such as total anti-oxidant capacity, malondialdehyde, protein carbonyl, advanced glycation end products. Furthermore, peripheral blood mononuclear cells (PBMCs) oxidative stress will be evaluated by measurement of reactive oxygen species (ROS), glutathione and the expression of SIRT1 and MnSOD and RAGE.