Early changes in the oxygenation of the skin may help predict foot disease in diabetes patients

Foot ulcerations are one of the most serious complications of diabetes, resulting in more than 80,000 lower-leg amputations each year in the U.S. alone.

A new study led by researchers at the Joslin-Beth Israel Deaconess Foot Center and Microcirculation Laboratory finds that early changes in the oxygenation of the skin could help foretell the development of ulcerations and enable doctors to treat patients at an earlier stage, before the onset of serious complications.

Reported in the Nov. 12 issue of the medical journal The Lancet, the study is part of a special issue devoted to diabetic foot disease.

"Nearly one in 40 diabetes patients will develop foot ulcers every year and more than 15 percent of these individuals will have to undergo amputation," explains Aristidis Veves, MD, DSc, research director of the Joslin-Beth Israel Deaconess Foot Center and Microcirculation Laboratory and associate professor of surgery at Harvard Medical School. "And, unfortunately, an amputation is often the beginning of a rapid downward cycle from which the patient never recovers."

The root of the problem is often a condition known as peripheral neuropathy, which develops when uncontrolled high blood sugar damages the nerves of the legs and feet, resulting in greatly decreased sensitivity.

"Peripheral neuropathy causes extreme numbness and a loss of protective sensation," explains Veves. "As a result, even a minor foot injury [such as a corn or callus, a splinter, or pressure from an improperly fitting shoe] can go undetected by the patient until it has escalated into a chronic wound that won't heal." Once an ulcer has become infected it can lead to the onset of gangrene, and in the most serious cases, to amputation of the limb.

Knowing that changes in large vessels and the microcirculation of the diabetic foot play a central role in the development of ulcers and their subsequent failure to heal, the authors set out to specifically identify what these changes are.

Using a novel technology known as medical hyperspectral imaging (MHSI), Veves and his colleagues studied a total of 108 patients – 21 control subjects who did not have diabetes, 36 diabetes patients who did not have neuropathy and 51 patients with both diabetes and neuropathy. They also measured foot muscle energy reserves using a magnetic spectroscopy, a new method that is based on magnetic resonance imaging (MRI).

As predicted, their results found that there are indeed measurable differences in the skin of diabetes patients – and, in particular, diabetes patients with peripheral neuropathy – that can be detected before ulcerative foot disease develops.

"Our results indicated that the amount of oxygen that is available is reduced in the skin of patients with diabetes, and that this impairment is accentuated in the presence of neuropathy in the foot," write the authors. Furthermore, says Veves, their findings showed that energy reserves of the foot muscles are reduced in the presence of diabetes, suggesting that microcirculatory changes could [also] have a major role.

"Foot problems are the most common reason for hospitalization among patients with diabetes," notes Veves. "But they are also among the most preventable. If problems can be diagnosed early, then interventions can be made that will have important effects on clinical management of the diabetic foot."