Patients with diabetes and PAD have already developed evidence of atherosclerosis and are at increased risk for myocardial infarction, stroke, or cardiovascular death, even without symptoms. One out of every three patients with diabetes who are older than 50 is estimated to have peripheral arterial disease (PAD), an atherosclerotic condition that can threaten “life and limb.” PAD is a warning of future heart disease, stroke, or death, and is a condition that can lead to amputation of the foot or leg if not properly treated.
Patients with atherosclerosis in a limb frequently also have it in their coronary and cerebral arteries. If PAD is identified, we know that the patient already has a very serious vascular problem. Once someone has PAD, the risk of developing a serious cardiovascular event, such as a heart attack, stroke, or death, increases to five or six times that of patients without PAD. Patients with diabetes primarily die from cardiovascular disease.
Many people with PAD do not present with symptoms. Approximately one third of patients with PAD have intermittent claudication-aching or fatigue in the leg muscles while walking even short distances and slow walking speed. Patients with severe PAD may develop pain in the foot or toes, or even sores and ulcers.
Especially for patients who are 50 or older and have diabetes and/or smoke, physicians should check the lower body for the following signs of PAD: decreased or absent pulse; bruits; cool, pale, or blue feet; and refractory wounds or necrosis in the feet and legs.
If ulcers appear on the toes or above the bones of the feet, or the foot becomes pale or cyanotic, the patient is at increased risk for gangrene and amputation, and a referral to a vascular specialist may be urgent.
The ankle-brachial index (ABI) is a simple test that can assist in the diagnosis of PAD. This noninvasive test determines the ratio of systolic blood pressure (SBP) levels taken in the arms and the ankles. A hand-held 5 to 10 MHz Doppler probe and a blood pressure cuff are the only tools needed to perform the ABI. Clinicians measure resting blood pressure levels in both arms and both ankles. The SBP measured at each ankle is then divided by the higher of the two brachial artery SBPs to derive the right and left ABIs. The normal range is an ABI between 0.91 and 1.30. Mild and moderate obstruction ranges from 0.40 to 0.90. Severe obstruction is defined as an ABI lower than 0.40 to 0.90. Severe obstruction is defined as an ABI lower than 0.40.
Patients with diabetes and PAD have already developed evidence of atherosclerosis and are at increased risk for myocardial infarction, stroke, or cardiovascular death even if they don’t have symptoms in their legs when they first visit their doctor. Physicians should check for signs of PAD during the routine physical examination every year. An ABI should be performed in all persons with diabetes who are older than 50 and in any that have symptoms of PAD. Patients who have PAD will need to be thoroughly educated on their condition because they must be absolutely meticulous in their foot care to prevent the formation of ulcers.
Established therapies are available to reduce the risk of atherosclerosis and its complications, particularly in patients with diabetes. These patients need aggressive treatment for their diabetes and other risk factors, including behavior modification and antiplatelet therapy. They should be advised to stop smoking, control hypertension, and begin statin therapy, which is now recommended for most patients with diabetes regardless of their cholesterol levels.
Many patients with intermittent claudication benefit from supervised exercise rehabilitation therapy, which involves walking on a treadmill or track for a minimum of 30 minutes at least three times a week for 12 weeks. Two drugs for patients with symptomatic PAD have been approved by the FDA, pentoxifylline and cilostazol. Of these, the one that is most effective for PAD is cilostazol, but this drug should not be used in patients with congestive heart failure. Endovascular interventions or surgical revascularization may be considered in some patients with severe symptoms of PAD. Any patient who has foot pain at rest or a sore, an ulcer, or gangrene developing in the foot has an urgent condition. That patient should be referred to a vascular specialist for evaluation and treatment.
We have not been aggressive enough in diagnosing PAD and other atherosclerotic diseases in patients with diabetes, nor have we been aggressive enough in instituting risk factor modification, antiplatelet therapy, and education about foot care and treating symptoms of PAD.