Introduction

The article that follows, “Peripheral Arterial Disease in People with Diabetes,” represents the American Diabetes Association’s (ADA’s) Consensus Statement on a common yet frequently underrecognized and undertreated condition. The statement was prepared by a vascular medicine panel chaired by Peter Sheehan, MD, past chair of the ADA Council on Foot Care. The statement was developed after a comprehensive consensus development conference, conducted through the American Diabetes Association–American College of Cardiology initiative entitled “Make the Link! Diabetes, Heart Disease and Stroke.” In view of the essential role that podiatric physicians play in the foot health of people with diabetes, JAPMA is reprinting, with permission, this important overview of peripheral arterial disease (PAD). This consensus statement examines the epidemiology and impact of PAD, specifically addressing the biology, evaluation, and treatment of this disease in people with diabetes.

Peripheral arterial disease is commonly seen in the day-to-day practice of podiatrists across the United States. It is a progressive condition characterized by arterial stenosis and occlusions in the peripheral arterial bed. It is a marker of systemic atherothrombotic disease in other vascular beds that is associated with considerable morbidity and mortality. The disease is linked to an elevated risk of cardiovascular and cerebrovascular events, including myocardial infarction, stroke, and death. The metabolic state of diabetes induces vascular dysfunction that predisposes these patients to atherosclerosis. Peripheral arterial disease is a significant public health issue.

People with diabetes have worse PAD below the knee than nondiabetics. Peripheral arterial disease has a negative impact on quality of life for people with diabetes and is associated with an increased risk of lower-extremity amputation. Diabetes is associated with a higher risk of developing PAD; however, early detection may be complicated by the presence of peripheral neuropathy and medial arterial calcification. Ischemic symptoms (intermittent claudication) may therefore be masked and ankle systolic pressures may appear falsely elevated. If PAD is considered to be a problem only in the case of intermittent claudication, then the majority of the at-risk population is missed. This constitutes the “silent majority” of patients with a low ankle-brachial index (ABI) but no claudication. The prevalence of asymptomatic disease can be estimated by using noninvasive techniques. The most widely used noninvasive test to detect asymptomatic disease has been the measurement of ankle systolic pressure. A resting ABI of less than 0.9 (mild obstruction) is believed to be associated with stenosis of 50% or greater and is 95% sensitive and 99% specific for angiographically documented PAD. An ABI of greater than 1.40 (poorly compressible vessels) is associated with a similar level of cardiovascular disease risk as an ABI of less than 0.9.

Diabetes and PAD are both complicated by neuropathy and foot ulceration, with increased risk of gangrene and amputation. Critical limb ischemia, manifested by rest pain, ulceration, or gangrene, is a threat to the limb and generally signals the need for revascularization or amputation.

Peripheral arterial disease requires a comprehensive clinical approach that includes physician awareness, recognition, and early intervention. Diabetes and tobacco smoking account for over 50% of the attributable risk of PAD. Screening programs are necessary for detection of PAD in people with diabetes. Even asymptomatic PAD places affected individuals at risk and calls for an aggressive approach to risk factor modification. Treatment guidelines recommend patient education about the disease, smoking cessation, control of diabetes, antiplatelet therapy (low-dose aspirin or clopidogrel), aggressive blood pressure control (<130/80 mm Hg) with an angiotensin-converting enzyme inhibitor, and lipid-lowering treatment with a statin (low-density lipoprotein cholesterol <100 mg/dL), as well as dietary and lifestyle modifications. Cigarette smoking is the single most important modifiable risk factor for the development and exacerbation of PAD.

There is ample clinical evidence to support the efficacy of the ABI as an effective diagnostic and risk-assessment tool that provides information on the severity of PAD. The ABI is useful to detect asymptomatic PAD. Limitations of the ABI include calcification of arteries that prevent occlusion of blood flow by the blood pressure cuff, resulting in an artificially elevated ABI. An ABI of greater than 1.3 suggests the presence of medial arterial calcification. The initial responsibility for detection of PAD rests with the primary-care provider. The responsibility for this evaluation may well be in the hands of the podiatric physician. The diagnosis of PAD begins with an accurate history and physical examination.

The ADA recommends that a screening ABI be performed for patients with diabetes who are over 50 years of age. If the results are normal, the test should be repeated every 5 years. A screening ABI should be considered in diabetic patients under 50 years of age who have other risk factors for PAD (eg, smoking, hypertension, hyperlipidemia, or duration of diabetes >10 years). A diagnostic ABI should be performed in any patient with symptoms of PAD.