Written by Dr. Matthew Capozzi, DPM, FACFAS, CWS (board-certified foot surgeon and wound specialist) · Medically reviewed by the CircuFiber Scientific Advisory Board · Updated: October 27, 2026

A diabetic foot ulcer is an open sore or wound, most often on the bottom of the foot, that develops when nerve damage, reduced blood flow, and repeated pressure cause the skin to break down. Diabetic foot ulcers occur when a layer of skin breaks down, allowing bacteria to enter and potentially cause infections. If left untreated, these ulcers can lead to serious health issues and in extreme cases, may even result in amputation. Every diabetic foot ulcer needs professional wound care from a podiatrist or wound specialist; it is not a problem to manage alone at home.

Key Takeaways

• A diabetic foot ulcer is an open wound that forms when skin breaks down, usually on the bottom of the foot, and it affects roughly 15% to 25% of people with diabetes at some point in their lives.
• The main causes are diabetic peripheral neuropathy (loss of protective sensation), peripheral artery disease (poor blood flow that slows healing), foot deformities, and poorly fitting footwear.
• Warning signs include an open sore, drainage or a foul smell, swelling, skin that turns red, brown, or black, and pain around the wound. Many ulcers are painless because of nerve damage.
• Treatment is professional: wound cleaning and dressings, debridement, offloading pressure, antibiotics for infection, and vascular procedures when blood flow is poor. Advanced options include negative pressure wound therapy, hyperbaric oxygen, and growth factor therapy.
• Prevention comes down to daily habits: inspect your feet every day, keep them clean and dry, moisturize (not between the toes), wear well-fitting shoes and non-binding socks, never go barefoot, keep blood sugar in range, and get a comprehensive foot exam at least once a year.
• See a doctor the same day for any sore that is not healing, and seek urgent care for spreading redness, pus, fever, or skin turning black.

What is a diabetic foot ulcer?

A diabetic foot ulcer is an open sore or wound that typically forms on the bottom of the foot in a person with diabetes. Diabetic foot ulcers are open sores that develop on the feet of individuals with diabetes, and they're a common complication caused by several factors like poor blood circulation and neuropathy. Diabetic foot ulcers occur when a layer of skin breaks down, allowing bacteria to enter and potentially cause infections. If left untreated, these ulcers can lead to serious health issues and in extreme cases, may even result in amputation. That's why it's essential to understand their causes, as well as the best methods for prevention and treatment. If you are not sure what an ulcer looks like, see our guide to early-stage diabetic foot ulcer pictures.

What causes diabetic foot ulcers?

Diabetic foot ulcers are caused by a combination of nerve damage, reduced blood flow, and repeated pressure or friction on the skin. Diabetic patients are at a higher risk for developing foot ulcers due to several factors, and most people who develop an ulcer have more than one of them at the same time.

Diabetic peripheral neuropathy (nerve damage)

The primary cause of foot ulcers in diabetic patients is neuropathy. Over time, diabetes can damage the nerves, making it difficult for patients to feel pain or discomfort. This increases the likelihood of developing ulcers as unnoticed injuries and pressure may cause skin breakdown. Nerve damage in the feet can cause loss of sensation, making it difficult to notice injuries or pressure points. Read more about diabetic neuropathy and how it affects the feet.

Peripheral artery disease (poor circulation)

Poor blood circulation is another significant factor contributing to ulcer development. Diabetes often affects blood vessels, leading to vascular diseases which further reduce blood flow to the extremities. Inadequate blood circulation reduces the body's ability to heal wounds and fight infections, making it easier for ulcers to form. Peripheral artery disease (PAD) reduces blood circulation to the feet, prevents quick healing of wounds, and can worsen existing ulcers.

Foot deformities and poorly fitting footwear

Foot deformities like bunions, hammertoes, and Charcot arthropathy make it more challenging for diabetic patients to find proper footwear, increasing pressure on certain areas of the foot and consequently raising the risk of ulcers. Shoes that are too tight or not well-cushioned can cause friction and pressure, contributing to ulcer formation. A thick diabetic foot callus over a pressure point is a common place for an ulcer to begin.

Additional risk factors

Additional risk factors that exacerbate the likelihood of diabetic foot ulcers are:

• Long-term diabetes: The longer a person has diabetes, the greater the chances of peripheral neuropathy and vascular diseases.
• Uncontrolled blood sugar levels: Poorly managed diabetes can result in more extensive nerve damage, reducing the body's ability to heal and increasing the risk of ulcers.
• Obesity: Being overweight puts undue pressure on the feet, exacerbating potential skin breakdown and ulcers.
• Smoking: Smoking disrupts blood circulation and hampers wound healing, making it a significant risk factor for ulcers.

What are the symptoms of a diabetic foot ulcer?

A primary symptom of a diabetic foot ulcer is the presence of an open sore or wound on the foot. This wound might ooze fluid or develop a foul smell. Because diabetic peripheral neuropathy blunts pain, many ulcers are painless and are first noticed as drainage on a sock, a spot of blood in a shoe, or swelling. Other common symptoms include:

• Swelling around the ulcer
• Discoloration of the skin, turning red, brown, or black
• Pain in the area surrounding the ulcer

The table below matches each symptom to what it may indicate and what to do.

What are the stages of a diabetic foot ulcer?

Diabetic foot ulcers progress from redness and swelling on intact skin to an open wound that can deepen into muscle, tendon, and bone. Understanding the stages of diabetic foot ulcers helps provide insight into their severity:

1. Stage 1: Redness and swelling, often accompanied by pain or discomfort
2. Stage 2: Breakdown of the skin, forming an open wound
3. Stage 3: Deepening of the wound, potentially involving muscles or tendons
4. Stage 4: Spread of infection to surrounding tissue and bones

Clinicians also use formal grading systems, such as the Wagner classification, to describe depth and infection. For a stage-by-stage walkthrough with pictures, read our article on the stages of diabetic foot ulcers.

What complications can a diabetic foot ulcer cause?

Diabetic foot ulcers can cause significant discomfort and may lead to serious complications, including infection, gangrene, bone infection, and amputation. It's crucial to attend to these symptoms, as ignoring them might result in complications. The following are some of the most common and serious complications associated with diabetic foot ulcers:

1. Infections: Diabetic foot ulcers are prone to bacterial infections. If an infection occurs, you may notice increased redness, pus discharge, or a foul smell. Left untreated, infections can spread through the tissues or even into the bloodstream, potentially causing life-threatening sepsis. Learn the signs of a diabetic foot infection.

2. Gangrene: Severe cases of infection or poor blood flow can lead to tissue death, aka gangrene. This condition is indicated by the skin turning black or blue and requires urgent medical care. In some cases, amputation may be necessary to prevent further tissue damage or spreading of the infection. Read more about diabetic foot gangrene and its treatment.

3. Bone infections (osteomyelitis): When an infection originating from a foot ulcer spreads deeper, it can affect the bones, necessitating a prolonged course of antibiotics or surgery to remove the infected bone.

4. Charcot foot: Damage to the nerves and blood vessels in the foot can weaken bones and joints, resulting in a condition known as Charcot foot. Symptoms include swelling, warmth, and redness, often with no apparent injury. If left untreated, it can lead to severe deformities and functional impairment.

How is a diabetic foot ulcer diagnosed?

Diagnosing a diabetic foot ulcer starts with a thorough examination by a healthcare professional. They'll assess the wound's depth, size, and location, and check for infections. During the diagnosis, a few tests might be performed, such as:

• Swab culture: helps identify any bacteria present in the ulcer.
• Blood tests: may reveal elevated levels of inflammatory markers, indicating infection.
• X-ray or MRI: can detect any underlying bone injury or osteomyelitis (bone infection).

Your clinician will usually also check the pulses and blood flow in your feet, because an ulcer with poor circulation heals differently from one with good circulation. A routine diabetic foot exam covers the same checks before an ulcer ever forms.

How do you treat a diabetic foot ulcer?

A diabetic foot ulcer is treated by a healthcare professional with a combination of infection control, removal of dead tissue, pressure offloading, and proper wound dressings. Prompt treatment of diabetic foot ulcers is crucial in preventing infection and minimizing the risk of amputation. The primary aims of diabetic foot ulcer treatment include:

1. Managing the infection through antibiotics, prescribed according to the identified bacteria.
2. Debridement, removing dead tissue and calluses from the ulcer, promoting healing and preventing further infection.
3. Employing offloading techniques such as customized footwear, walking casts, or crutches to redistribute pressure and relieve the affected area.

Ensuring proper blood flow to the affected area through vascular procedures may also be needed when peripheral artery disease is limiting healing.

Wound dressings and advanced therapies

We'd like to share some other significant treatment options:

• Wound dressings: keeping the ulcer clean and moist with proper dressings, as suggested by a healthcare professional, is crucial.
• Negative pressure wound therapy (NPWT): involves application of controlled suction to the area, promoting healing by removing excess fluids and stimulating tissue growth.
• Hyperbaric oxygen therapy (HBOT): patients breathe 100% oxygen in a pressurized chamber, thereby improving the oxygen supply to the affected tissues and promoting wound healing.
• Growth factor therapy: applying growth factors directly to the ulcer to expedite the healing process.

What you should not do at home

Do not cut away calluses or dead skin yourself, do not soak an open ulcer, and do not apply over-the-counter creams or home remedies to the wound unless your clinician has told you to. Keep weight off the ulcer as instructed, keep the dressing clean and dry, and keep every follow-up appointment. By selecting appropriate treatments and following healthcare professionals' advice, we can help prevent complications and ensure a faster recovery.

How can you prevent diabetic foot ulcers?

Diabetic foot ulcers are prevented with daily foot inspection, good hygiene, protective footwear, blood sugar control, and regular professional foot exams. An essential part of managing diabetes is preventing diabetic foot ulcers (DFUs).

Daily foot care

Proper foot care is crucial for those with diabetes. Here are some vital steps to take:

• Inspect your feet daily for cuts, blisters, redness, or swelling. Early detection enables timely treatment and reduces the risk of complications.
• Wash your feet with mild soap and warm water every day. Dry them thoroughly, paying particular attention to the areas between the toes.
• Moisturize your feet to avoid dry skin, which may lead to cracks and potential infections. Avoid applying moisturizer between the toes since excess moistness can promote fungal growth. See our guide to cracked feet and diabetes.
• Trim your toenails regularly, straight across, to avoid injury.

Protect your feet from injury

Protecting your feet from injury is equally important. Consider the following recommendations:

• Wear properly fitted shoes that provide ample support and cushioning. Avoid tight, ill-fitting shoes that can cause pressure sores, blisters, or cuts.
• Rotate your footwear to allow for proper drying and discourage bacterial growth.
• Avoid walking barefoot both indoors and outdoors to minimize the risk of cuts, punctures, or burns.

Keep blood sugar in range

In addition to foot care and protection, it's essential to maintain healthy blood sugar levels since high glucose levels impair wound healing. Implement these strategies:

• Monitor your blood sugar regularly and follow your doctor's advice for maintaining optimum levels.
• Stick to a healthy diet that's low in saturated fats, sugars, and refined carbohydrates. Include more fresh fruits, vegetables, whole grains, lean proteins, and healthy fats.
• Stay active by engaging in regular physical activity, such as walking, swimming, or biking, with your doctor's approval. Movement also supports circulation; see six ways to improve circulation with diabetes.

See your healthcare team regularly

Let's not forget the importance of regularly scheduling appointments with your healthcare team:

• Have a comprehensive foot exam at least once a year, or more frequently if recommended by your doctor.
• Promptly report any foot-related concerns or changes to your healthcare team. Early intervention is critical for preventing complications.

Can diabetic socks help with diabetic foot care?

Diabetic socks are one part of everyday protection for feet with intact skin; they do not treat, heal, or prevent ulcers. A well-designed diabetic sock has a non-binding top that does not squeeze the leg or restrict blood flow, a seamless construction that reduces friction over toes and pressure points, and moisture-wicking fabric that helps keep skin dry. Those three features address the friction, pressure, and moisture that daily foot care is meant to control. For how they differ from compression socks, see diabetic socks vs. compression socks.

CircuFiber diabetic socks are seamless, moisture-wicking, and non-binding, and the fabric is woven with Circulight® IR fibers containing thermoreactive mineral particles that absorb body heat and reflect it back into the foot as far-infrared energy, which promotes a temporary increase in local blood flow and circulation. In a randomized, double-blinded, placebo-controlled trial at Yale School of Medicine (ClinicalTrials.gov NCT04460612, published in Diabetes & Vascular Disease Research, 2023), the active textile significantly increased transcutaneous oxygen in the feet of people with diabetes compared with a placebo sock, with the difference visible at 40 minutes and significant at 60 minutes. CircuFiber socks also carry the APMA Seal of Acceptance.

If you have an open wound, do not wear any sock over it unless your podiatrist or wound clinician approves it and tells you how to dress the wound underneath. Socks are for protecting intact skin as part of a daily foot-care routine, not a substitute for professional wound care.

When should you see a doctor about a diabetic foot ulcer?

See a podiatrist or your doctor the same day you notice any open sore, blister, crack, or wound on your foot that is not healing, even if it does not hurt. Seek urgent care for drainage or pus, a foul smell, spreading redness or warmth, fever, or skin turning black or blue, because these are signs of infection or tissue death. Also report a warm, red, swollen foot with no visible wound, which can be Charcot foot. Remember that timely intervention plays a key role in successful treatment, so always consult your healthcare professional if you notice any signs of a developing foot ulcer. Not sure who to call? Read how to choose a diabetic foot doctor.

Frequently asked questions about diabetic foot ulcers

What does a diabetic foot ulcer look like?

A diabetic foot ulcer usually looks like a round or oval open sore on the ball of the foot, the heel, or the tip or side of a toe, often with a ring of thick callus around it. The base may be pink, red, yellow, or black, and there may be drainage. Early on it can look like a blister, a blood blister under a callus, or a small crack. Our early-stage ulcer pictures show what to watch for.

What does an early-stage diabetic foot ulcer look like?

An early-stage diabetic foot ulcer shows up as redness and swelling on a pressure point, sometimes with a callus, blister, or a small break in the skin before the wound opens fully. Because of neuropathy it is often painless, so a daily visual check is the only reliable way to catch it. Any such spot that does not resolve within a few days should be seen by a podiatrist.

Can you die from a diabetic foot ulcer?

A diabetic foot ulcer itself is rarely fatal, but its complications can be. An untreated infection can spread through the tissues or into the bloodstream, potentially causing life-threatening sepsis, and ulcers that lead to amputation carry a higher long-term mortality. Early professional treatment is what keeps an ulcer from reaching that point.

How long does a diabetic foot ulcer take to heal?

Healing time varies widely, from a few weeks for a shallow ulcer with good blood flow and consistent offloading to many months for a deep or infected ulcer with poor circulation. Keeping weight off the wound, keeping blood sugar in range, not smoking, and keeping every wound-care appointment are the factors you control.

What is the best cream or antibiotic for a diabetic foot ulcer?

There is no over-the-counter cream that substitutes for professional wound care. Antibiotics are prescribed according to the bacteria identified by a swab culture, and dressings are chosen by your clinician to keep the wound clean and moist. Do not apply creams, ointments, or home remedies to an open ulcer unless your healthcare provider has directed it.

Can a non-diabetic person get a foot ulcer?

Yes. Foot ulcers also occur in people without diabetes from peripheral artery disease, venous disease, pressure injuries, and other causes of nerve damage. Diabetes makes ulcers far more common because it combines nerve damage, poor circulation, and impaired healing in the same foot.

References, studies and sources

• National Center for Biotechnology Information (NCBI) / StatPearls. Diabetic Foot Ulcer. https://www.ncbi.nlm.nih.gov/books/NBK537328/
• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Diabetes and Foot Problems. https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/foot-problems
• American Diabetes Association. Foot Complications. https://diabetes.org/about-diabetes/complications/foot-complications
• American Podiatric Medical Association (APMA). Diabetic Wound Care. https://www.apma.org/patients-and-the-public/conditions-affecting-the-foot-and-ankle/diabetic-wound-care/
• Yale School of Medicine. Randomized, double-blinded, placebo-controlled trial of an infrared textile on transcutaneous oxygen in people with diabetes. ClinicalTrials.gov NCT04460612. https://clinicaltrials.gov/study/NCT04460612

About the author: Dr. Matthew Capozzi, DPM, FACFAS, CWS, is a board-certified foot surgeon through the American Board of Foot and Ankle Surgery. He is a Diplomate of the American Academy of Wound Management and Fellow of the American College of Foot and Ankle Surgeons. He completed a three-year residency program in Foot and Ankle Reconstructive Surgery at St. Francis Hospital & Medical Center in Hartford, CT in 2010. Dr. Capozzi is a board-certified Wound Specialist® granted by the American Academy of Wound Management.

Healthcare disclaimer: Always consult your physician before beginning any program. This general information is not intended to diagnose any medical condition or to replace your healthcare professional. If you experience any pain or difficulty, stop and consult your healthcare provider. CircuFiber socks are a general wellness product intended to promote a temporary increase in local blood flow and circulation; they are not intended to diagnose, treat, cure, or prevent any disease. Individual results vary.