Ficus glumosa Del (Moraceae) commonly called “African rock fig” is a large tree indigenous to southern part of Nigeria. Its stem bark has been of interest to researchers because of its use in the treatment of various disease conditions in Nigerian traditional medicine. The present study was aimed at evaluating the antidiabetic and antioxidant properties of the methanol extract of F. glumosa stem bark using alloxan-induced diabetic mice. The extract, at the dose of 62.5, 125, and 250 mg/kg showed a remarkable time-dependent decrease in blood glucose level in alloxan-induced diabetic mice. There was no significant difference between the extract-treated groups and the groups treated with 10 mg/kg distilled water and glibenclamide (2 mg/kg) respectively. At 6-h post-treatment, the blood glucose level for the groups treated with 62.5 mg/kg of F. glumosa and glibenclamide (2 mg/kg), respectively, were lower than the normal blood glucose level respectively for the groups before the induction of diabetes. F. glumosa showed its optimum antioxidant activity in DPPH spectrophotometric assay at the concentration of 100 μg/ml. The ferric reducing antioxidant power showed a significant concentration dependent increase in the total antioxidant power. These findings demonstrate that F. glumosa has both antidiabetic and antioxidant effects on experimental model of diabetes in mice and validate its use in Nigerian traditional medicine for the treatment of diabetes. Even in its crude form, the effects, especially at 62.5 mg/kg, were comparable to that of glibenclamide, an oral sulfonylurea with proven antidiabetic activity. This finding suggests that the extract could be a potential source of a novel antidiabetic and antioxidant agent for the treatment of diabetes mellitus.