Free radical-induced lipid peroxidation has been associated with numerous disease processes including diabetes mellitus. Glutathione-S-transferase (GST) catalyses the conjugation of glutathione with a variety of organic peroxides to form more water-soluble compounds. Glucose-6-phosphate dehydrogenase (G6PDH) is essential to control intracellular reductive potential by increasing glutathione intracellular levels, which in turn decrease the amount of reactive oxygen species. Glyburide decreases glucose production and enhances insulin action in liver. The aim of this study was to examine the effects of glyburide on the antioxidant enzyme activities in the liver tissue of diabetic rat. We investigated the activities of GST and G6PDH in the liver of both control and streptozotocin-induced diabetic rats. Forty male albino rats were included in this study. Liver GST and G6PDH activities decreased significantly in five-week diabetic rats (p < 0.001 and p < 0.001 respectively) compared to controls and glyburide therapy restored these activities (p < 0.001 for GST and p < 0.001 for G6PDH). Elevations of hepatic antioxidant enzymes with glyburide administration suggest that glyburide may directly alter hepatic enzyme activities.