effect of supplementation of diet with vitamin c on induction and consequences of stz-diabetes in rats

objective: streptozotocin (stz) destroys the beta cells of pancreas by generation of reactive oxygen species and vitamin c has documented antioxidant properties. this study was designed to evaluate the preventive effect of supplementation of diet by vitamin c on induction of stz-diabetes and its effect on carbohydrate and lipid metabolism of diabetic rats. materials and methods: fifty male wistar rats were divided randomly into non-diabetic (nd), diabetic (d), c1, c2 and c3 groups. the diet of c1, c2 and c3 groups were supplemented with 2.5, 5 and 10 g/kg of vitamin c, respectively. four days later all groups except nd, were made diabetic by ip injection of stz and blood glucose was measured 72 h later to determine the severity of blood glucose elevation. weight gain was measured weekly. 21 days after induction of diabetes glycosylated hemoglobin (hba1c), triglyceride (tg), total cholesterol (tc), hdl-c and ldl-c were measured or calculated in plasma of 6 diabetic rats in each groups that their glucose was more than 200 mg/dl after stz injection. results: vitamin c significantly prevented blood glucose elevation after stz injection in group c2. weight gain decreased in all diabetic groups. increase of hba1c could not be prevented by vitamin c in any groups. tc and ldl-c decreased and hdl% increased in group c3. conclusion: we suggest that the amount of vitamin c consumption may have an important effect on stz-diabetes induction and it may be in agreement with opposite effects of free radicals on insulin receptor signaling. furthermore, vitamin c may have some beneficial effects on lipid metabolism disorders of diabetes.