Diabetic foot ulcers are frequently complicated by the presence of arterial occlusive disease (PAD). It is often difficult to assess the severity of ischemia by history and physical examination alone; a combination of different types of noninvasive laboratory testing may be necessary. Pulse-volume recordings and segmental pressures should be routinely obtained. If questions persist, an anatomic study is warranted. Duplex ultrasonography can provide accurate information with little risk to the patient and so should be readily obtained.