Treatments for Diabetic Wounds
Top therapies for stubborn wounds that won't heal
Diabetic wounds are some of the most dangerous and common complications of diabetes. Fifteen percent of people with diabetes will have one at some point, and caring for them costs $20 billion per year in the United States—not including an estimated 2 million workdays lost as a result of foot wounds that won’t heal.
That’s the bad news. The good news: Doctors are getting better at healing these wounds, and fewer of them lead to amputations. According to a 2012 study, the rate of leg and foot amputations among adults with diabetes in the United States declined by 65 percent between 1996 and 2008. With knowledge and preparation, wounds can be tackled early or avoided entirely.
Odds Are Stacked
One of the biggest factors influencing whether someone with diabetes develops a hard-to-treat wound is neuropathy, nerve damage that can numb sensation in the affected parts of the body. People with diabetes are at particular risk: 60 to 70 percent will develop some sort of neuropathy, and the likelihood increases with age and poor blood glucose control.
With neuropathy, someone with diabetes might take longer to notice a small cut or blister. Those extra days or even weeks can give infections a chance to establish themselves. (Signs of infection include redness, warmth, swelling, yellowish or clear discharge, and pain.) Neuropathy’s a risk factor for not noticing a wound and for letting it get severe before treating it, says Randall Wolcott, MD, director of the Southwest Regional Wound Care Center in Lubbock, Texas.
Another factor is the compromised immune system that often accompanies diabetes. High blood glucose levels slow down the immune cells that the body unleashes to fight off infections. When bacteria move in to colonize an open wound on the foot, the defenses that would ordinarily push them out are slowor ineffective.
Finally, people with diabetes often have problems with their circulation. “Diabetes affects the blood supply and heart, but also small blood vessels,” says Crystal Holmes, DPM, a professor of podiatry at the University of Michigan Health System. Sluggish circulation hampers the blood supply needed to support healthy tissue growth.
Combined, those factors can lead to chronic wounds called ulcers. They’re most often found on the feet, in part because the feet are most often where neuropathy and circulatory problems strike.
With proper treatment, ulcers can frequently be reversed. But when an infection reaches the bone, amputation is usually necessary. “Studies have shown that people with diabetes are 30 times more likely to undergo an amputation than people without diabetes,” says Wolcott. In the United States, 73,000 people with diabetes have a lower leg amputated each year.
It’s an outcome foot-care specialists are desperate to avoid. Within two years, Wolcott says, half of those with amputations get diabetic wounds on their remaining foot—often because they put more pressure on their remaining leg while wearing a prosthesis or using crutches. That, in turn, sets them up for more infections and a second amputation. “Once you get a leg amputation, it’s tough to recover,” Wolcott says.
That’s why it’s important to recognize the problem early. “If I can save a limb, I can save a life,” Holmes says.
Prompt, expert treatment can mean the difference between healing and amputation. That’s why people with diabetes must take the initiative. “It’s important to have a plan,” says Holmes. “It’s better to call me early than wait a month—then I’m probably going to be doing an amputation.”
Ultimately, the goal is to give the body a fighting chance against the infection, helping it clear out the bacteria and close the skin. Doctors may use a variety of tools to treat infected wounds, from debridement—a technical term for removing dead or infected tissue surgically—to antibiotics, pressure chambers, and even insect larvae.
Such treatments are critical: Dead tissue gets in the way of immune cells and other healing factors in the blood and the bacteria they’re trying to kill, slowing wound healing. “It’s more important what you take off than what you put on,” Holmes says about removing affected flesh. “Having a good blood supply is key—when you deliver antibiotics, they need to be able to get there.”
Once a wound’s been treated,it’s crucial it gets special care. Dressings are applied to diabetic wounds after debridement to keep them clean and promote healing. They can be wet or dry, depending on the wound and the treatment your doctor selects, and sometimes contain antibiotics or other medication. From there, it’s a good idea to stay off of the wound until it’s had time to heal. “Pressure relief is critical,” says Holmes. “When you’re walking, you put two to three times your body weight on your feet.”
Much the same way doctors put a cast on a broken arm to give the bone time to mend itself, patients with foot ulcers are often given special boots or even asked to use a wheelchair for as long as it takes to clear up the wound. Depending on the size and severity, that can be a matter of weeks or even months.
As inconvenient as it often is to stay off the affected limb, doing so is key to recovery. “Patients don’t want to go into devices, but if you broke your arm you’d expect a doctor to put a cast on it,” Holmes says.
When bacteria collect, they become more than the sum of their parts. Large colonies of bacteria work together to form a protective layer of slime called a biofilm, which shields them from immune cells and antibiotics.
These slimy barriers go up everywhere, from your kitchen counter to the inside of sewage pipes. Depending on when you last brushed, you may be able to find a sample in your mouth. The most familiar form of biofilm is probably dental plaque.
Biofilms also play a major role in diabetic foot ulcers. Once established, they dig in and hang on, overwhelming and eating up the plasma cells the body sends to root them out. “Biofilm diseases are parasitic—they don’t degrade or kill; they inflame and then eat the plasma [cells] that come out,” says Wolcott.
From behind their biofilm wall, bacteria can hang on indefinitely. It takes 100 to 1,000 times more antibiotic to kill bacteria protected by biofilms as it does to kill bacteria floating around on their own.
That’s why it’s often necessary for surgeons to intervene in diabetic foot wounds. Wolcott compares treating biofilms to treating dental plaque: Just as we use dental floss, toothbrushes, and regular visits to a dental hygienist to break up the biofilms covering our teeth, wound-care specialists have a variety of tools at their disposal to physically break up the biofilms in wounds, cutting, scrubbing, washing, or even having them eaten away.
Once the coating of slime is gone, or disrupted, it’s easier to kill off the bacteria that formed it.
Doctors can use scalpels and lasers, ultrasound devices, chemicals, and enzymes to remove dead tissue and biofilm from diabetic foot wounds. Increasingly, they’re turning to a surprising, squirming remedy. Certain species of blowfly larvae feed only on dead or decaying flesh, making them ideal for cleaning out diabetic foot wounds.
Blowfly larvae were first used to clean wounds in the 1920s, after military doctors noticed that soldiers with maggot-infested wounds often recovered better. But the treatment fell out of use after the introduction of antibiotics and surgical techniques.
Live blowfly larvae are considered prescription medical devices by the Food and Drug Administration (FDA). They’re raised in controlled, sterile environments, then applied to wounds and contained using a special bandage “cage.” A few days later, doctors remove them. Patients with neuropathy, in particular, are great candidates for the treatment because they can’t feel the maggots. Not surprisingly, the sensation of maggots is something many patients won’t tolerate, although studies on people who have received the therapy suggest most patients can get over the “ick” factor.
From the outside, the infections that cause diabetic wounds are no different for people without diabetes. But what about on the inside?
Mayland Chang, PhD, a biochemist with the University of Notre Dame, wanted to know if there was something different about the way the bodies of people with diabetes responded to infections. Specifically, she wondered if enzymes called matrix metalloproteinases (MMPs for short) might work differently in people with diabetes.
MMPs help the body break down and build up tissue, a critical part of both fighting infections and healing wounds. They’re usually noticed in fetal development and cancer growth, two situations in which the body is working unusually hard to build new cells. There are many varieties of the protein, and researchers are just beginning to learn that different varieties might have different properties.
Chang received a grant from the American Diabetes Association to investigate MMPs in diabetic wounds. Working with specially bred diabetic mice, she found that more of a variety called MMP-9 turned up in diabetic wounds, whereas nondiabetic wounds contained more of an enzyme called MMP-8.
Chang’s early results suggest MMP-9 might be one reason people with diabetes have a harder time healing. “When we inhibit MMP-9, we accelerate wound healing,” she says. “But when we inhibited MMP-8, we made healing worse. MMP-9 might be part of the reason wounds won’t heal.”
The discovery could be the basis for treatment, if researchers can figure out a safe and effective way to add MMP-8 to diabetic wounds while blocking the body from producing MMP-9.
- Check your feet frequently for cuts and scrapes, and treat broken skin with care. For more helpful foot-care tips, visit diabetesforecast.org/healthyfeet.
- Have a doctor examine your feet. In its 2016 Standards of Medical Care in Diabetes, the American Diabetes Association recommends yearly foot exams to screen for problems, including ulcers.
Neuropathy can dry out the skin, leading to cracks that can invite infection. To prevent that, slather on a moisturizer daily—but skip between the toes, where extra moisture can lead to bacterial and fungal growth.
Protect Your Feet
If you have a loss of sensation in your feet, wear closed-toe shoes—even when you’re indoors—to lower your risk of developing a skin injury that could develop into a foot wound.
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