The impact of diabetes on intermittent claudication was examined in 1813 men and 2504 women with 34-yr follow-up data in the Framingham study. For both sexes, diabetes was associated with a two- to threefold excess risk of intermittent claudication compared with its absence. A pronounced excess risk was also observed in subjects on oral hypoglycemic therapy and in women receiving insulin. Although diabetes was often associated with an atherogenic-risk profile, controlling for age and several concomitant risk factors failed to eliminate the association with intermittent claudication. Those who developed both intermittent claudication and diabetes were at an especially high risk of incident cardiovascular events. In women, the risk of coronary heart disease, stroke, and cardiac failure was increased 3-4 times when diabetes and intermittent claudication occurred together compared with when either condition existed alone. In diabetic men, the presence of intermittent claudication doubled the risk of stroke, and cardiac failure was approximately 3 times more likely in subjects with both conditions compared with either alone. We conclude that diabetes is an important risk factor for intermittent claudication, which in turn confers a serious prognosis for subsequent cardiovascular outcomes in the patient with diabetes.