Diabetes is associated with hyperglycemia, one of the most important causes of oxidative stress. Endogenous antioxidants are able to destroy the reactive species and create a balance between antioxidant and free radicals. In diabetes, the oxidative stress is increased due to the deficiency in the antioxidant defense. The intake of antioxidants, such as vitamin E, may reduce the oxidative stress associated with diabetes and hence help to restore the antioxidant defense system. The aim of this article was to investigate the effect of different doses of vitamin E on the biochemical parameters of normal and streptozotocin (STZ)-induced diabetic rats. Biochemical analysis was used to study the effect of this vitamin on the biochemical parameters of normal and diabetic rats. The plasma levels of alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactic dehydrogenase (LDH), and gamma-glutamyl transferase (γ-GT) were significantly increased after the onset of diabetes. In addition, STZ-induced diabetes also caused an increase in the level of blood urea nitrogen (BUN) and creatinine. Oral administration of vitamin E (0.2-0.4 mg daily) significantly (P < 0.05) decreased the plasma level of ALT, AST, and γ-GT. In addition, there was a slight but not significant reduction in the plasma level of ALP. Parameters of kidney function, such as BUN and creatinine, were slightly reduced after the oral administration of vitamin E. The plasma level of electrolytes, such as calcium and sodium, also changed significantly (P < 0.00001) after the oral administration of vitamin E. Vitamin E ameliorates the metabolic and biochemical parameters of diabetic rats.