Diabetes Forecast

How to Keep Your Feet

Avoiding peripheral vascular disease

By Sheldon H. Gottlieb, MD, FACC , , ,

]It was a medical student milestone: the end of our first lecture on how to examine a patient. A classmate of mine stood up and anxiously asked a question: "Does the patient have to take off their shoes and socks when you examine them?"

A murmur of tense, embarrassed laughter rippled through the classroom. I could see, however, that the professor had enjoyed the question. "Yes," he replied, "the patient must take off their shoes and socks when you examine them, and you must examine the feet—for many people, especially if they have diabetes, it's the most important part of the physical exam.

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"Look carefully at your patients' feet," he continued, warming to the subject. "Are they trim and healthy looking with an even coloration, or are they swollen and discolored red or blue? Can you feel the pulse of the dorsalis pedis artery that runs down the top of the foot, or the posterior tibial artery, which hides behind the anklebone? If the arteries aren't getting blood to the toes, you won't see hair on them. Is there thickened, dried skin (known as a callus) under the big toe or on the ball of the foot? Are there ulcers on the tip of the big toe or the side of the little toe? Are the toenails trimmed and healthy looking, or are they thickened or neglected looking? When you tap on the Achilles tendon on the back of the foot, do you get a healthy-feeling 'ankle jerk,' or does it feel like you are tapping your reflex hammer on the floor? How flexible is the foot? Does it feel like it would slip comfortably into a normal shoe, or do the feet feel like slabs of overcooked roast beef? Is the ankle joint intact? Do the toes look relaxed and spread evenly, or are they humped up hammertoes that seem to say 'get me out of here!'?"

He concluded: "Healthy people have feet that look healthy, feel healthy, and that even smell healthy." Again, there was a ripple of laughter through the classroom, but it sounded relaxed. We had learned a lesson.

Diabetes poses two major risks to the feet. You may already have heard that glucose out of control can damage the nerves that provide protective sensation to the feet. But diabetes, in combination with other risk factors, can also cause disease of the arteries that feed the feet. This is peripheral vascular disease, or PVD, and it is directly related to the health of your heart.

The first warning sign of danger to the feet is usually an ulcer. Those caused by neuropathy are usually under the thickened skin of a callus, under the big toe, or the ball of the foot (the area of the sole under the big toe joint). Ulcers caused by PVD are often at the tip of the big toe (you can't get further away from the heart) or at the side of the fifth (pinky) toe. And ulcers caused by neuropathy or PVD ulcers are the beginning of the end for many people with diabetes. They often lead to one of the most feared complications of diabetes: amputation of a foot or leg. The survival rate after amputation is poor. And people with both diabetes and advanced PVD almost always have advanced disease in the blood vessels of other vital areas of the body, such as the heart and the brain.

Work by the group led by Lewis Kuller, MD, at the University of Pittsburgh, published in the journal Atherosclerosis in 1991, showed that a simple test measuring the balance between the blood pressure in the arms and the feet was an important indicator of risk of dying from vascular disease. They called this test the "Ankle-Brachial Index," or ABI. Many studies have since shown that the ABI is a sensitive and specific early indicator of the extent of vascular disease. (For reasons that are quite unclear, diabetes rarely affects arteries in the arms.)

The ABI test can be done with a very simple and inexpensive hand-held "Doppler" probe, the size of a number 2 pencil, and the technique can be easily taught to health care providers in private practice. A study published by Mallik R. Thatipelli, MBBS, and associates at the Mayo Clinic in 2007 showed that the simple ABI test often provided more information than that obtained by stress testing with a complex and very expensive stress echo machine.

At the Scientific Sessions of the American Diabetes Association in 2005, it was reported that only about 14 percent of health care providers include foot exams at every office visit. I hope that my medical school classmates and your personal health care providers are doing a better job than that.

Sheldon H. Gottlieb, MD, FACC, is a cardiologist at Johns Hopkins Bayview Medical Center, Department of Cardiology, in Baltimore.



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