The hypoglycemic effect of Collybia confluens exobiopolymer was investigated in streptozotocin (STZ)-induced diabetic rats. In a dose-dependent study, the exobiopolymer, at 150 mg/kg body weight (BW) dose substantially lowered the plasma glucose level by 29.3%, as compared to the control group. It also lowered the plasma total cholesterol and triglyceride levels by 23.3 and 30.7%, respectively, and reduced the liver total cholesterol and triglyceride levels by 23.0 and 33.5%, respectively. The activity of alanine transaminase (ALT) and aspartate transaminase (AST) was reduced 34.6% and 23.6% respectively, by the exobiopolymer administration, compared to the control group. The exobiopolymer was found to contain 83.2% carbohydrate and 16.8% protein. The sugar and amino acid of the exobiopolymer were also analyzed in detail.