Abstract: In the present investigation, antidiabetic and antioxidant activities of a polyherbomineral formulation, Gly-13-C was evaluated in streptozotocin-induced diabetic male Wistar rats and compared with that of glibenclamide (600 μg kg-1), a reference drug. After induction of diabetes by a single intraperitoneal injection of streptozotocin (65 mg kg-1), diabetic animals were treated with different doses of Gly-13-C (100, 200 mg kg-1 and 400 mg kg-1 b.wt.) for 21 days. Various biochemical parameters-fasting plasma glucose, albumin fructosamine levels, liver enzymatic antioxidants like superoxide dismutase, catalase, non-enzymatic antioxidants like vitamin C and E, lipid peroxidation in liver and glycogen biosynthesis in liver and skeletal muscle were measured. Study results showed that Gly-13-C 200 and 400 mg kg-1 b.wt. demonstrated better glycemic control and significantly protected liver tissue against oxidative damage than reference drug.