Objectives: There is strong evidence that diabetes results a state of oxidative stress and that reactive oxygen species contribute to the production of insulin resistance, β-cell dysfunction and both the microvascular and macrovascular long-term complications of diabetes. Antioxidants are used as supportive therapy in the treatment of DM, so, we use ozone and vitamin C to study if they can regulate the oxidative complications of DM.  Material and method: twenty male adult albino rats were divided into two groups; group 1: control group, group 2: alloxan induced diabetic rats which divided into three subgroups. subgroup1: diabetic untreated rats, subgroup2: diabetic treated with ozone and subgroup 3: diabetic rats treated with vitamin C. After thirty days of treatment the body weight gain was detected. Blood sample were collected to1- estimate biochemical parameters as: glucose, serum insulin, lipid and protein profiles and liver and kidney functions 2- estimate some hematological parameters. Also, liver samples collected to determine their glycogen content and pancreatic samples were obtained for microscopic and quantitative evaluation. Results: in diabetic untreated rats the results showed reduction of gained body weight, hyperglycemia, and hypoinsulinemia, significant increase in liver and kidney functions and change in lipid and protein profiles and decreased liver glycogen content. While, O₃ and vitamin C treated rats reported an amelioration of the most toxic effect of alloxan and returned most of these parameters nearly normal. Microscopically pancreatic beta cells showed definite vaculation, degeneration, karyolysis and pyknosis in the diabetic group while pancreatic alpha and delta cells were not affected. The use of O₃ and vitamin C treatment in this study showed significant improves of such cellular changes when compared to diabetic untreated rats but still abnormal when compared with normal rats. Conclusion: it was recommended that the use of the O₃ or vitamin C as a supplementary agent to reduce oxidative stress damage of hyperglycemia and recommended to use variable doses and different periods of treatment to evaluate the best dose and period.