Hypoglycemic effects of exo-biopolymers (EBP) produced by submerged mycelial cultures of Coriolus versicolor, Cordyceps sinensis, Paecilomyces japonica, Armillariella mellea, and Fomes fomentarius were investigated in streptozotocin (STZ)-induced diabetic rats. The rats from each experimental group were orally administered with EBPs (100 mg/kg BW) daily for 2 weeks. Though the hypoglycemic effect was achieved in all the cases, however, C. versicolor EBP proved as the most potent one. The administration of the C. versicolor EBP substantially reduced (29.9%) the plasma glucose level as compared to the saline administered group (control). It also reduced the plasma total cholesterol (TC), triglyceride (TG), aspartate aminotransferase (AST) and, alanine aminotransferase (ALT) levels by 9.22, 23.83, 16.93, and 27.31%, respectively. The sugar and amino acid compositions of this EBP were also analyzed in detail.