We investigated the antihyperglycemic and antioxidant activities of polysaccharides produced from Pleurotus ferulae mutant in streptozotocin-induced diabetic rats. Blood glucose level in the STZ-induced diabetic rat administered the extract polysaccharides, 250mg/kg b·w/d (EPSG) was 196.97mg/dL, approximately 54.12% less compared to that of the STZ-induced diabetic rats administered 0.9% NaCl solution (NCG). The insulin level in the EPSG was approximately 1.64-fold higher than that in the NCG. HDL and LDL cholesterol levels in the EPSG were 29.15mg/L and 20.35mg/dL, respectively, representing an approximate increase of 69.18% and decrease of 38.52%, respectively. The activities of aspartate aminotransferase (AST) and alanine transferase (ALT) in the EPSG decreased approximately by 49.27 and 50.43%, respectively, while the alkaline phosphatase (ALP) activity decreased by 34.25%, relative to the NCG. Antioxidant activities in the NCG decreased relative to the normal group. In contrast, for EPSG, these values increased relative to the NCG. The malondialdehyde level in the EPSG was 12.95mmol/mg protein, which was approximately 70.64% of that in the NCG. These results suggest that the polysaccharides of Pleurotus ferulae mutant could be developed as potential antidiabetic agents or functional foods for people with a high risk of diabetes mellitus.