OBJECTIVE: Patients with lower extremity arterial disease (LEAD) are at an increased risk of having coronary artery disease (CAD). Diabetics are at especially high risk for having LEAD with concomitant CAD. This study was undertaken (1) to define the clinical and arteriographic features associated with CAD among diabetics and nondiabetics with LEAD and (2) to determine the long-term survival and predictors of mortality of diabetics and nondiabetics with LEAD and CAD. RESEARCH DESIGN AND METHODS: Two hundred sixty-three diabetics and 1137 nondiabetics from the Coronary Artery Surgery Study who had evidence of LEAD, who were 50 years and older, and who had arteriographically proven CAD were monitored for a mean of 12.8 years. RESULTS: Among all the subjects with LEAD there was a high prevalence of current and past smoking, history of previous myocardial infarction, systemic hypertension, congestive heart failure, high degrees of angina pectoris and unstable angina pectoris, and use of beta-blockers. On arteriographic evaluation a high prevalence of three-vessel epicardial coronary disease and involvement of multiple coronary segments with > or =50% diameter narrowing was found. Multivariate analysis showed the number of coronary segments with >50% occlusion, the presence of cerebrovascular disease, the use of digitalis, and elevated systolic blood pressure were independently associated with diabetes. On follow-up diabetics had a significantly higher mortality rate (mostly cardiac) than nondiabetics: median survival, 8.1 years and 12.7 years, respectively. At 15 years the mortality rates were 77.1% and 62.0%, respectively. On multivariate analysis, age, number of coronary occlusions, number of significantly narrowed epicardial arteries, diminished myocardial contractility, hypertension, and smoking were significant predictors of mortality in the total group and in each subgroup. Coronary artery bypass grafting surgery was protective. The presence of diabetes was an independent risk factor for mortality. CONCLUSIONS: The presence of LEAD is associated with multivessel epicardial and multiple coronary segment occlusion. On long-term follow-up there is a high mortality rate. In patients with LEAD and diabetes, CAD is especially severe and prognosis is poor.