Succinic acid mono ethyl ester (EMS) was recently proposed as an insulinotropic tool in the treatment of non-insulin dependent diabetes mellitus. The aim of this study was to investigate the effect of EMS on oxidative stress in a streptozotocin (STZ)-nicotinamide induced type 2 diabetic model. The EMS was injected intraperitoneally at 8 micro mol/g body weight for 30 days. Plasma glucose, plasma insulin, thiobarbituricacid reactive substances (TBARS), hydroperoxides, superoxide dismutase (SOD), catalase (CAT), glutathione peroxide (Gpx), reduced glutathione (GSH), glutathione-S-transferase (GST), and vitamins C and E were assayed in liver and kidney. Treatment with EMS and metformin to diabetic rats resulted in a significant reduction in plasma glucose, TBARS, and hydroperoxides. In addition, the treated groups also showed a significant increase in the activities of plasma insulin, SOD, CAT, GPx, GST, GSH, vitamin C, and vitamin E in liver and kidney of STZ-nicotinamide-induced diabetic rats. Our result suggest that non glucidic nutrient, such as EMS as a potent antidiabetic, may optimalize antiperoxidative and antioxidants status by restoring the biochemical alterations found in STZ-nicotinamide-induced type 2 diabetes.