Groups of Cohen diabetic rats, aged 30 days were treated with Acarbose (40 mg per 100 g sucrose diet) for 3, 5 and 7 months. Siblings of the same sex were used as controls and fed the sucrose diet alone. The dose of Acarbose was adjusted in a preliminary study and found to be tolerated by the animals. Acarbose treatment resulted in a significant reduction of the 2 hr postprandial blood glucose. No elevation of the plasma insulin was noted. A significant decreased incidence and severity of glomerulosclerosis was not in the 3 months Acarbose treated groups (P less than 0.05) and in the 5 and 7 months (P less than 0.01) in comparison with the controls. In the 7 months Acarbose treated group the longevity was significantly longer than in the control (P less than 0.05). In the 3 and 5 months groups, increased longevity was not apparent as the animals were sacrificed before having the opportunity to manifest the difference.