A growing body of evidence suggests the potential role of chymase in organ injury in diabetes. We investigated blood glucose levels and survival in transgenic mice carrying the human chymase gene (Tg). Intraperitoneal injections of streptozotocin (STZ) (200, 100, 75 and 50 mg/kg in total, i.p.) were given to uninephrectomized Tg mice and wild-type C57BL/6 (BL) mice. Before STZ injection, the Tg mice had significantly lower body weights and slightly higher systolic blood pressure as compared with the BL mice. STZ-treated Tg mice showed significantly higher postprandial blood glucose levels as compared with the STZ-treated BL mice. The survival prevalence of STZ-treated Tg mice was zero, whereas BL mice showed a value of 40% until 42 days. STZ (100, 75 or 50 mg/kg, i.p.)-treated Tg mice also showed a similar pattern as compared with the STZ-treated BL mice. These data suggest that human chymase contributes to blood glucose levels and mortality during the progression of diabetes.