Oxidative stress plays a key role in the pathogenesis of diabetes complications. Chronic hyperglycemia and disturbed lipid regulation commonly seen in diabetes are the main causes of this process. Despite the critical role of oxidative stress in diabetes, most clinical trials with available antioxidants and vitamins have either failed to show any long term benefits or have produced inconsistent results (10-11). There has been growing interest in establishing the possible roles of oral hypoglycemic agents including Metformin in reduction of oxidative stress. Metformin, the most common prescribed oral medication in type 2 diabetes, lowers HbA1c around 1.5%, rarely causes hypoglycemia (compared with insulin or sulfonylureas), has relatively few contraindications, its adverse effects are generally tolerable, does not cause weight gain, is cheap, and is highly acceptable among patients. Given the long term benefits observed with metformin use, a role in modulating oxidative stress is imputable. We designed this study to evaluate the actions of metformin on oxidative stress in a group of medication-naïve newly diagnosed type 2 diabetes patients.