Background: Various herbs have been used for treating several diseases. Rosemary is a thorny plant which is widely distributed in Europe and South-Eastern Asia. It is used in traditional medicine for its therapeutic properties. Objective: Evaluation of the biological antioxidant mechanisms of Rosemary leaves extract in the reduction of blood glucose level and lipid profile. Materials and Methods: Sixty adult male albino rats were used in this study. The rats were divided into six equal groups, i.e.  Control, Rosemary control group, alloxan-treated, alloxan plus glibenclamide-treated group, alloxan plus Rosemary-treated group and finally alloxan plus both glibenclamide and Rosemary-treated group. Blood samples were obtained for determination of fasting blood glucose, total cholesterol, triglycerides, HDL- cholesterol, LDL-cholesterol, atherogenic index as well as malondialdehyde (MDA) and catalase. Results: Treatment with rosemary leaves extract was found to be effective in ameliorating blood glucose, lipid profile and antioxidant levels. Conclusion: Rosemary leaves extract has a beneficial effect as an anti-diabetic agent as well as improving lipid metabolism in diabetics.