Study: Hot Spots Warn of Diabetic Foot Ulcers

Diabetics, watch out: A hot spot on your foot can signal an ulcer is brewing, a wound that could cost your limb. New research shows that using a special thermometer to measure the temperature of their soles can give patients enough early warning to avoid one of diabetes' most intractable complications.

It's a simple-sounding protection for such a huge problem. Foot ulcers each year strike 600,000 U.S. diabetics, people slow to notice they even have a wound because diabetes has numbed their feet.

"They've lost the gift of pain," says Dr. David Armstrong of Chicago's Rosalind Franklin University of Medicine and Science, a diabetic foot specialist.

Worse, foot ulcers are so slow-healing and vulnerable to infection that they're to blame for most of the roughly 80,000 amputations of toes, feet and lower legs that diabetics undergo each year.

So word that an easy-to-use gadget could help is generating excitement. Using the thermometer reduced by nearly two-thirds the number of high-risk patients who got foot ulcers, Armstrong found in a study of 225 diabetic veterans, the third in a series of government-funded research to back the approach.

How does it work?

Inflammation goes along with tissue injury, and inflammation can be measured by a bump in temperature. It's subtle — a minimum 4-degree difference between, say, your right big toe and your left one that can occur days before the skin breaks.

"A wound really will heat up before it breaks down," Armstrong explains.

Patients measure half a dozen spots on each foot. When the thermometer signals a hot spot, they put up their feet for a day or so until the temperature normalizes. Easing pressure before the skin cracks lets the body heal more easily than it can with a full-blown wound.

"Heat is one of the most sensitive things, one of the first things that happens when we begin to have tissue breakdown," says Dr. Crystal Holmes, a University of Michigan podiatrist who has begun prescribing the thermometers.

"It's looking positive that this sort of testing could be quite useful," adds Dr. Theresa Jones, who oversees research on diabetes complications at the National Institutes of Health. "There isn't any other treatment one knows about to (help) at that point before there's an ulcer."

This isn't a standard thermometer, but a $150 infrared one with a tip that digitally measures skin temperature on contact.

Maker Xilas Medical, with an NIH grant, is working to make the thermometer resemble a bathroom scale: Step up, and it would automatically flash any trouble spots to the patient, and to a computer that alerts the doctor.

That's still a few years from market. For now, San Antonio-based Xilas sells the handheld TempTouch by prescription only.

Insurance coverage is mixed. But, "how cheap compared to an amputation," says Dr. Mary Ann Banerji, who heads the State University of New York Downstate Medical Center's diabetes center.

Treating a simple diabetic foot ulcer can cost $8,000, double that for an infected one and even more for an amputation.

"It's basically idiot-proof," Walter Massa of Skokie, Ill., says of the thermometer.

"On the other hand, it's very hard to take your temperature when you don't think there's a problem there," cautions Massa, 53, who has used the thermometer since Armstrong helped him narrowly avoid amputation when the joints in his foot disintegrated. "There's something you have to teach yourself."

Some 21 million Americans have diabetes, meaning their bodies can't properly regulate blood sugar, or glucose. Over many years, high glucose levels seriously damage blood vessels and nerves that lead to, among other things, loss of sensation in the feet and poor blood flow in the lower legs — the ulcer environment.

There is little therapy to avert foot ulcers. Patients are urged to wear proper-fitting shoes and check their feet daily for redness, bumps or other signs of trouble.

But day-to-day changes are hard to spot. In an NIH-funded study last year, Texas A&M College of Medicine researchers reported 30 percent of patients got ulcers even when using a mirror to check their soles, compared with 8.5 percent of thermometer users.

The new study, funded by the Department of Veterans Affairs and published in last month's American Journal of Medicine, is the biggest yet, tracking 225 patients for 18 months. Some 12.2 percent who did standard feet checks got ulcers, compared with 4.7 percent of thermometer users.

Participant Paul Rau of Green Valley, Ariz., had a recurring ulcer on his left big toe for six years, a quarter-inch bone-deep hole that took weeks to heal each time. While using the thermometer, Rau says his ulcer came back far less frequently, and when it did it was a quick-healing shallow crack.

"How it helped me was I checked my feet better," says Rau, 60. "There were so many points on your feet you had to do."

While the results are compelling, the studies are small and NIH's Jones says the thermometer should be included in larger studies to prove long-term benefit.