OBJECTIVE - Patients who have diabetes and lower-extremity arterial disease (LEAD) are at an increased risk of dying from coronary artery disease (CAD). This study was undertaken to: 1) define the clinical and arteriographic factors associated with LEAD among diabetic patients; 2) determine the long-term survival and predictors of mortality of diabetic patients with LEAD, compared to those without LEAD; and 3) determine if the presence of LEAD is an independent risk factor for mortality among diabetic patients with CAD. RESEARCH DESIGN AND METHODS - A total of 263 diabetic patients from the Coronary Artery Surgery Study (CASS) registry with LEAD, who were ≤50 years of age, and who had arteriographically proven CAD, were identified and followed for a mean of 12.8 years. A total of 1,349 comparably aged diabetic patients from the CASS registry with CAD and no evidence of LEAD were followed for an equivalent period of time. RESULTS - Compared with diabetic patients without LEAD, diabetic patients with LEAD were characterized by the presence of cerebrovascular disease, a high rate of current smoking, elevated systolic blood pressure, high grades of angina pectoris, and digitalis use. Severity of epicardial CAD and extent of CAD were not independent predictors of the presence of LEAD. On follow-up, diabetic patients with LEAD had significantly higher mortality (mostly cardiovascular) than diabetic patients without LEAD, with a median survival of 8.1 and 10.9 years, respectively. On multivariate analysis, age, the number of significantly narrowed coronary arteries, and the presence of left ventricular dysfunction predicted mortality in both subsets of diabetic patients. Among all the diabetic patients with CAD, the presence of LEAD was an independent risk factor for mortality. CONCLUSIONS - Diabetic patients with LEAD have a higher mortality rate (mostly cardiovascular) than diabetic patients without LEAD, despite no apparent anatomic differences in the severity and extent of CAD. This suggests that factors associated with the presence of LEAD, other than the anatomy of the coronary circulation, may play a role in determining survival among diabetic patients with LEAD and CAD.