The aim of the present study is to determine if a combination of vitamins (C and E) has any advantage over insulin therapy on lipid peroxidation, antioxidant activity, liver dysfunction parameters, and histological changes in the alloxan-induced diabetic rats. The enzymatic activities of glutathione peroxidase (GPX), superoxide dismutase (SOD), and catalase (CAT) and the lipid peroxidation product, thiobarbituric acid-reacting substances (TBARS) were measured in liver and pancreas as indicators of antioxidation in these tissues. The liver dysfunction parameters: the activity of lactate dehydrogenase (LDH), gamma glutamyl transferase (GGT), phosphatase alkalines (PAL), aspartate and lactate transaminase (AST and ALT) were measured in serum. In diabetic rats, the TBARS contents of the liver and pancreatic tissues were found to have significantly increased as compared to non-diabetic rats (P < 0.001). The SOD, CAT, and GPX activities in the liver and pancreas in diabetic rats significantly decreased as compared to normal rats (P < 0.001). AST, ALT, LDH, GGT, and PAL activities increased in the diabetic rats (p > 0.05). In diabetic rats treated with insulin or with combined vitamins (C and E), an ameliorative effect was observed. This amelioration was more pronounced in the group of rats treated with combined vitamins (C and E).