Worried about ulcer problems? It may be time to take your foot temperature.

As many as a quarter of people with diabetes develop foot ulcers, which can escalate into gangrene, bone infection, and possibly even lower limb amputation. But a simple surveillance tool—a foot thermometer—can help prevent these dangerous sores, according to recent research.

Ulcers form when diabetic neuropathy numbs the extremities to pain. Without being able to feel that sting, a person can be oblivious to a developing ulcer. However, there’s another way to predict whether an ulcer is about to bloom, says David Armstrong, DPM, MSc, PhD, professor of surgery at the Rosalind Franklin University of Medicine and Science in Chicago: a rise in skin temperature.

Armstrong and his team found that patients who measured foot temperatures were only a third as likely to develop ulcers, compared with those without thermometers. Their findings were reported in the Dec. 2007 issue of The American Journal of Medicine.

The study enrolled 225 veterans with diabetes who were at high risk for foot ulcerations. All were educated about foot care and ulcer signs, but half were also issued special thermometers designed for taking surface skin temperatures. Twice a day, participants tested six positions on each foot, and recorded the readings in a journal. The researchers advised them that foot-skin temperature should only vary a half degree between sites; any temperature differences greater than four degrees indicate inflammation—a tell-tale sign that an ulcer is brewing.

They told anyone who registered such high readings to contact the study nurse and rest until the temperature equalized. Some didn’t heed this advice, and developed ulcers. These participants recorded foot temperatures five degrees greater than normal at the site where ulceration would occur for up to a week before the skin actually broke.

By the end of the 18-month study, five thermometer-users developed ulcers, compared with 14 of the other veterans. The study does not say, however, whether the lower ulceration resulted from the temperature readings themselves or the increased attention paid to feet during thermometer use.

“It seems like, for whatever reason, this draws people into their own care,” says Armstrong. “It’s so simple and inexpensive, it’s exciting.”

The medical thermometers used in the study cost $150 each, although Armstrong predicts the price will drop. In addition, the company that supplied the thermometers is developing a foot thermometer that one steps on like a bathroom scale.