The present study was conducted to evaluate the usefulness of four kinds of legumes(black soybean: BS, yellow soybean: YS, green peas: GP, soybean curd residue: SCR) as a high-fiber supplement in the therapeutic diet for diabetic patients. Seven groups of normal and streptozotocin-induced diabetic rats were fed isocaloric experimental diets containing 8% dietary fiber from one of legumes for 6 weeks. The effects of legumes on the gastrointestinal function and diabetic symptoms in diabetic rats were also examined and compared with the effects of cellulose or pectin diet. Legume supplementations had no significant effects on alleviating typical diabetic symptoms such as polydipsia, polyphasia, polyuria, and urinary glucose excretion when compared with cellulose or pectin supplementations. The supplementations of legumes all resulted in remarkable changes in gastrointestinal functions: shortening of GI transit time and increases in fecal volume, fecal water and crude fat contents. Legume supplementations appeared to supress the damages of the small intestine villi and the enteritis symptoms in diabetic rats. GP led to regular villus patterns closer to normal villus. BS, YS and GP led to the enlargement of cecum in diabetic rats. In conclusion, the present studies have demonstrated that legumes may possess a significant physiological actions in the control of various diabetic conditions.