Background: Finding a treatment for diabetes that does not have side effects has remained elusive. Among natural agents, much attention has been focused on phenolic compounds. For both their medicinal and nutritional value, barberry plants are of particular interest. Berberis vulgaris is known for its medicinal benefits in Iranian traditional medicine. In this study, we investigated the biological activities of B.vulgaris in a rodent model of experimentally induced diabetes. Method: The fasting blood glucose (FBG), insulin, malondialdehyde (MDA), and total antioxidant levels were measured in experimental groups of rats, including normoglycemic control, diabetic control, and diabetics treated with B.vulgaris, and the gene expression of the stress proteins HSF-1, HSP27, and HSP70 as well as the enzymes glucokinase (GK) and glucose 6-phosphatase (G6P) were assayed by real-time PCR.