Diabetic Foot Ulcers

A diabetic ulcer is an open sore in which partial or full thickness of the skin is lost in a person who has diabetes. These often occur on the feet in people with diabetes mellitus. They usually are painless because the person has decreased sensation in the feet.

The lifetime risk of developing a diabetic foot ulcer is between 19% and 34% in those people with diabetes. Unfortunately, recurrence is also common. After initial healing, approximately 40% of people have a recurrence within one year, almost 60% within three years, and 65% within five years.

But having diabetes does not mean you will inevitably develop a sore or foot ulcer. Understanding how these types of wounds occur and how to properly care for your feet can help you prevent, detect, and treat these wounds before they progress to something worse.

This article will review the causes of sores and ulcers, common types, conditions leading up to ulcers, and treatment of existing ulcers, both complicated and uncomplicated.

Causes

People with diabetes who have peripheral neuropathy (nerve damage usually in the limbs) and ischemia (lack of blood flow, typically caused by peripheral arterial disease, PAD) are at increased risk of developing diabetic foot ulcers and other foot abnormalities.

Loss of protective sensation, defined as the inability to feel pain and temperature, is the most common risk factor for foot ulceration. Complicated foot ulcers can increase the risk of infection, amputation (surgery to remove the foot), and even death (due to sepsis, an extreme response to infection). Ulcers do not occur spontaneously but rather because of a combination of factors.

Neuropathy: Neuropathy is a general term for nerve dysfunction. Peripheral neuropathy is the most common type of neuropathy in people with diabetes and typically affects the nerves of the feet, legs, and sometimes the arms and hands.

People with diabetes are at increased risk for peripheral neuropathy if they have a history of hyperglycemia (high blood sugar) and have had diabetes for a long time. Other risk factors for neuropathy include smoking and genetic predisposition.

Over time elevated blood sugar levels can affect nerve functioning and nerve signaling. Small nerve dysfunction results in the inability to feel pain, and large fiber dysfunction causes disturbances in balance, which can increase the risk of falls.

If a person has neuropathy and injures their foot without feeling it, they may not notice it until it gets much worse. Recurrent, unnoticed injuries to the foot can increase the risk of Charcot foot, in which progressive destruction of the bones and joints leads to foot deformity.

Autonomic neuropathy can cause a decrease in sweating, resulting in dry feet. Having dry feet can increase the risk of developing calluses. While calluses are healthy, if you have lost sensation, they can grow deeper cause damage to the skin surface known as breakdown, putting the foot at risk of blisters or ulcers.

Peripheral arterial disease (PAD): PAD occurs when one or more arteries that supply blood to the legs and feet are blocked or partially blocked due to atherosclerosis. Neuropathy and PAD often coexist and can cause an increase in foot ulcers. PAD is estimated to be present in as many as 50 to 60% of patients with diabetic foot ulcers.

Deformities: Deformities such as Charcot foot or hammertoe (in which the toe is bent at its middle joint) can increase the risk of skin breaking down.

For example, in a person with diabetes who lacks sensation, a hammertoe that is repeatedly pressed against a shoe can cause the skin to break down and increase the risk of a foot ulcer. Most of the time, people with deformities will have other risk factors for ulcers.

Age/sex/duration of diabetes: Age and duration of diabetes can increase the risk of ulcers and amputations by twofold to fourfold. Male sex is associated with a 1.6-fold increase in foot ulcer risk. In the United States, ulceration is more common among people of Latinx, Native American, or African-Caribbean descent.

Other foot trauma: An improperly fitting shoe, a foreign object in the shoe, or stepping on something sharp can all cause a person with diabetes can experience skin breakdown or injury. An injury can be complicated by delayed wound healing due to inadequate blood flow and elevated blood sugars.

Previous ulceration: It is estimated that the annual incidence of foot ulcers in people with previous ulceration is 30%–50%.

Other types of microvascular complications: A person with diabetes who has other microvascular complications (relating to the smaller blood vessels) such as diabetic retinopathy (damage to small blood vessels in the eyes), and those with kidney disease receiving dialysis (treatment to remove wastes your kidney cannot) are at increased risk of developing foot ulcers.

People who have received transplants: People with diabetes who have received transplants of a kidney, pancreas, or kidney-pancreas combined are at increased risk of developing ulcers.

Neuropathy and chemical trauma: Inappropriate use of creams for corns and calluses can lead to ulceration in a person who has neuropathy and diabetes.

Types

Certain foot issues can increase the risk of developing foot ulcers in people with diabetes:

• Calluses and blisters: Plantar (bottom of the foot) calluses and blisters are associated with an increased risk of developing ulcers. A callus is thickened skin that develops to help alleviate a pressure site and can go into deeper layers of skin. Blisters develop from sheer forces and friction, allowing skin layers to separate and fill with blood or serous fluid. Both can occur due to dry skin and improperly fitting shoes.
• Erythema: Warm, reddened skin called erythema can occur in people with diabetes when there is neuropathy or increased plantar pressures. Too much pressure on the foot can cause the skin to break down.
• Fungal infections: People with diabetes are at increased risk of developing fungal infections. Untreated fungal infections between the toes can cause the skin to break down and increase the risk of an ulcer. On the bottom of the foot, it can result in dry skin and fissures (small tears in the skin) that can lead to skin breakdown.
• Ulcer: It is common for ulcers to occur on the soles of the feet, the toes, the front of the foot, and ankles. Diabetic foot ulcers tend to occur in areas prone to trauma, like the sites of calluses or over bony prominences.

The most common type of ulcer is a painless neuropathic ulcer resulting from peripheral neuropathy. These can occur due to a foot injury, such as banging into something or stepping on a foreign object. They can also develop with small, repetitive trauma that is constant for days to months in the same area.

Ulcers associated with peripheral arteial disease (reduced blood flow) are less common. They are painful when the foot is elevated or flat on the bed, but less painful when the foot is down as gravity brings it more blood. Depending on the severity of the ulcer, ulcers can be complicated or uncomplicated.

Treatment

Treatment will usually require a multidisciplinary approach to achieve remission. Foot ulcers and wound care may require care by a podiatrist, orthopedic or vascular surgeon, infectious disease specialist, plastic surgeon, or rehabilitation specialist experienced in managing diabetes.

The actual treatment of the wound will depend on its severity and whether there is tissue loss, ischemia, or infection.

Wound care: Wound care is a generalized term for treating the actual ulcer and will vary depending on factors such as its size and depth, the presence of an infection, blood flow, and your nutritional status. The cause of the wound will directly impact the treatment regimen.

Different creams, products, and materials will be used between physicians and even at different times of your treatment, depending on how the wound is affected.

Debridement:Debridement is removal of necrotic (dead), damaged, or infected tissue to allow for healing to occur. There are many types of debridement techniques that can be used.

Infections: Early detection and treatment of infected wounds can help to prevent serious complications, including hospitalization and amputation. Not all ulcers are infected. It is suspected when there are signs such as warmth, redness, drainage, or a bad odor.

Assessment of the infection will require collecting a wound culture, blood sampling, X-rays, and (in some instances) advanced imaging.

For most infected wounds, topical or oral antibiotics are needed. The type of antibiotic prescribed will depend on the type and severity of the infection. Antibiotics treat the infection, but the wound still needs healing. They are not meant to prevent a recurring infection.

Infection may spread to the bone, called osteomyelitis. If there is necrotic bone (death of bone tissue), the person may need surgical resection (removal of the affected bone and tissues).

People who have chronic, previously treated, or severe infections or are at risk for antibiotic-resistant infections will need a referral to specialized care.

Off-loading: Off-loading is one of the most important steps in wound healing because it removes pressure from the ulcer and allows healing tissue to form. Off-loading refers to the use of devices or surgeries that remove pressure or reduce the "load" at the site of ulceration to improve healing.

This is often necessary, especially in people with diabetes who cannot feel pain. If they continue to put pressure on the wound, it will continue to break down and worsen.

People can off-load their wound by using therapeutic shoes and custom insoles, wearing postoperative shoes or sandals, padded dressings, removable cast boots (RCBs), and casting. These devices are referred to as total contact casts (TCC) and protect the foot by not allowing movement in the joints.

Establishing adequate blood circulation: Establishing a person's blood flow will be important in wound healing. For people with an ulcer who also have PAD, revascularization procedures may be necessary. These procedures aim to reopen the blood vessels.

After four weeks of wound care and off-loading, some experts refer people to a vascular limb salvage specialist for further evaluate the wound for evascularization.

Nutritional support and blood glucose control: People with diabetes who have hyperglycemia will benefit from getting their blood sugar (glucose) levels under control. Adequate blood sugar control can assist in wound healing.

A general increase in protein intake (unless there are restrictions due to kidney disease) can help rebuild healthy tissue. Also, vitamin C and zinc can help heal wounds.

Reach out to a registered dietitian specializing in diabetes, such as a certified diabetes care and education specialist, to assist in individualized meal planning and patient-centered education.

Foot-care education: Receiving in-depth foot care about peripheral neuropathy, the causes of ulcers and infections, warning signs, and preventative measures will assist people in detecting and treating wounds.

Adjunctive therapies for wound treatment: There are many types of adjunctive therapies for wound treatment. These are treatments given in addition to the primary therapy. Standard wound care may not be optimal for all. Starting adjunctive therapies early may improve outcomes.

Researchers note the following adjunctive treatments have some evidence for use with diabetic foot ulcers:

• Bioengineered cell-based therapies: These use fibroblasts (cells that make fibrin) in a matrix or scaffold applied to the ulcer. Examples are Apligraf and Dermagraft,
• Acellular matrices: This is a temporary skin layer made of collagen, glycosaminoglycan chondroitin-6-sulfate, and silicone.
• Placental-derived membranes:
• Recombinant growth factors: Regranex is a bioengineered platelet growth factor approved by the Food and Drug Administration (FDA) to treat diabetic foot ulcers.
• Platelet-rich plasma: A sample of the person's blood is centrifuged and the layer containing platelets (cells involved in clotting) is used.
• Placental-derived membranes: These are based on human placental tissues. Grafix is an example.
• Hyperbaric oxygen therapy is approved by the FDA for the treatment of nonhealing diabetic foot ulcers, severe skin and bone infections, and more. The person enters a chamber in which atmospheric pressure is raised so they breathe in more oxygen, and more oxygen is delivered to the tissues.
• Vacuum-assisted closure (VAC), also called negative pressure wound therapy (NPWT), uses a vacuum and a sponge applied to the wound. It removes fluid from the site and stretches the new healthy skin cells to fill the wound.

If you have a chronic ulcer that has not improved or decreased in size by about 50% in four weeks, then looking into adjunctive therapies could help. Discuss your options with your physician.

Skin graft: You may wish to consult with a plastic surgeon for a skin graft. This requires an operating room and hospital stay. In a skin graft, healthy skin is harvested from your own body and used to cover the ulcer.

Prevention

Preventing foot ulcers is the absolute best way to prevent recurrence. Keeping blood sugar levels in check can also help. Good glycemic control can help prevent some of the causes of foot ulcers, including peripheral neuropathy.

Lifestyle changes such as exercising to increase blood flow, stopping smoking, and losing weight can also improve glycemic control, as well as improve your overall health.

Practicing good foot hygiene (washing your feet, wearing clean cotton socks) and inspecting your feet daily is important. It is prudent to avoid walking around barefoot and always shake out your shoes before you put them on.

In addition, if you have neuropathy or are at increased risk of an ulcer, having proper-fitting shoes or therapeutic footwear can help prevent the chance of developing an ulcer.

Seeing a podiatrist regularly is also a good prevention step. In people with diabetes, this should be covered by most insurance plans (including Medicare). A podiatrist can cut toenails and debride calluses. They will evaluate for neuropathy and provide education and care advice.

Creating Awareness

Diabetic ulcers are costly and difficult to treat. They can increase the risk of amputation and severely impact a person's quality of life. Clinicians, experts, and diabetes-care advocates are doing their part in creating awareness about diabetic foot ulcers. Effective detection and treatment can reduce the burden.

While there already are many FDA-approved adjunctive therapies for wound treatment, we can expect to see more in the future. In fact, in February 2020 the FDA provided clearance to market a new treatment, ActiGraft. Clearance is given when a product proves it is substantially the same as an already legally marketed device.

ActiGraft uses a person's own blood to create a blood clot. The blood clot is used to treat chronic and difficult wounds and ulcers. The company suggests that this treatment method is more effective as it treats the wound throughout the healing stages and is less costly.

Summary

Diabetic sores and foot ulcers are serious side effects of diabetes that can be prevented. Educating people on the importance of proper foot care, neuropathy, and their risk for PAD is important for prevention. People at risk for ulcers should check their feet daily. Depending on the severity of the ulcer, treatment will vary.

A Word From Verywell

Having diabetes does not mean you will automatically develop a foot ulcer. But there are certain risk factors to take into consideration. If you have had diabetes for a long time, have had a previous foot ulcer, have neuropathy or PAD, you may have a higher chance of developing foot ulcers.

Talk to your healthcare provider about how to properly clean, inspect, and moisturize your feet, as well as ways to improve your nutrition and get your blood sugar under control.

Early detection and treatment will yield better results if you develop an ulcer. The good news is you have many options for care.