OBJECTIVE: The Captopril Prevention Project (CAPPP) evaluated the effects of an ACE inhibitor-based therapeutic regimen on cardiovascular mortality and morbidity in hypertension. One planned subanalysis of the CAPPP was to evaluate the outcome in the diabetic patient group. RESEARCH DESIGN AND METHODS: In the CAPPP, 572 (4.9% of 10,985 hypertensive patients) had diabetes at baseline and were studied according to a prospective, randomized, open, blinded, end point trial design. Patients aged 25-66 years with diastolic blood pressure > or =100 mmHg were included and randomized to receive either captopril or conventional antihypertensive treatment (diuretics and/or beta-blockers). RESULTS: The primary end point, fatal and nonfatal myocardial infarction and stroke as well as other cardiovascular deaths, was markedly lower in the captopril than in the conventional therapy group (relative risk [RR] = 0.59; P = 0.018). Specifically, cardiovascular mortality, defined as fatal stroke and myocardial infarction, sudden death, and other cardiovascular death, tended to be lower in the captopril group (RR = 0.48; P = 0.084), and no difference was observed between the study groups for stroke (RR = 1.02; P = 0.96). Myocardial infarctions were less frequent in the captopril group than in the conventional therapy group (RR = 0.34; P = 0.002). Furthermore, total mortality was lower in the captopril as compared with the conventional therapy group (RR = 0.54; P = 0.034). Patients with impaired metabolic control seemed to benefit the most from ACE inhibitor-based therapy. CONCLUSIONS: Captopril is superior to a diuretic/beta-blocker antihypertensive treatment regimen in preventing cardiovascular events in hypertensive diabetic patients, especially in those with metabolic decompensation.