The purpose of this study was to determine the effects of taurine supplementation and taurine depletion on blood glucose and blood lipid concentrations in insulin-treated diabetic rats. Four groups of Sprague-Dawley male rats were fed the purified diet for 3 weeks ; nontaurine-supplemented diabetic rats(E0), nontaurine-supplemented diabetic rats with insulin treatment(E0＋I), 1% taurine-supplemented diabetic rats with insulin treatment(E1＋I) and taurine-depleted diabetic rats with insulin treatment(EA＋I). Diabetes was induced by streptozotocin injection(50mg/kg B.W.). Isophane insulin was given subcutaneously into the abdominal wall of the diabetic rats(4 unit/rat/day). E1＋I were supplemented with 1% taurine in drinking water. To induce taurine depletion, EA＋I were treated with 5% $eta$-alanine in drinking water. E1＋I had significantly higher body weight compared to that of E0. The food intakes of E1＋I and E0＋I were significantly decreased compared to that of E0. There was no sigfniciant difference in food intake between E1＋I and E0＋I. The water intake of rats was significantly different among the groups ; E0>E0＋I>E1＋I>EA＋I. The urine volume of E0 was significantly increased compared to those of insulin-treated goups. The blood glucose concentration of E0 was significantly increased compared to those of insulin-treated groups. In the oral glucose tolerance test(OGTT), E0＋I and E1＋I had significantly lower blood blucose concentrations compared to E0 after 30 min. Also EA＋I had significantly lower bloodglucose concentrtion compared to E0 and E0＋I. The plasma total cholesterol and LDL-cholesterol concentratons of EA＋I were significantly incrased compared to those of other groups. Therefore, it may be suggested that tuarine supplementation is useful for insulin-dependent diabetes in order to prevent diabetic complications suchas cardiac vascular diseases.