Background and Objective: Diabetes mellitus and its oxidative complications are progressing around the world and plant-based products appear to be promising alternative treatments. The present study aimed to evaluate the antioxidant potential of the leaves of Glyphaea brevis (Tiliaceae) in an experimental model of diabetic rats. Materials and Methods: Diabetes mellitus was induced by intravenous injection of streptozotocin (STZ). Aqueous and hydroethanolic extracts of G. brevis leaves (AE and HEE respectively) were given daily at doses of 250 and 500 mg/kg by gastric intubation for 30 days. Antioxidant status of rats was determined in extracellular as well as in intracellular compartments by assessing ferric-reducing antioxidant power, enzymatic antioxidants (catalase, superoxide dismutase, and glutathione peroxidase) and non-enzymatic antioxidants (protein thiols). Results: As compared with untreated diabetic rats, administration of extracts led to significantly higher values of ferric-reducing antioxidant power, enzymatic and non-enzymatic antioxidants in all compartments. Conclusion: These results suggest that G. brevis extracts have antioxidant activity that could find applications in the management of oxidative complications of diabetes mellitus.