A diabetic foot ulcer is an open sore on the foot of a person with diabetes. It often forms on the bottom of the foot.

A foot ulcer is often painless. Diabetes can reduce feeling in your feet, so may not feel a sore when it starts. Look for sores instead of waiting for pain. If you care for someone with diabetes, look at their feet too.

Up to about one in three people with diabetes gets a foot ulcer at some point in their life. A foot ulcer comes before about four in five leg and foot amputations in people with diabetes.

What Is a Diabetic Foot Ulcer?

A diabetic foot ulcer is a break in the skin of the foot in a person with diabetes. The break goes through at least the top layer of skin and into part of the layer below. It is a type of chronic wound that can be slow to heal.

Ulcers often form on parts of the foot that carry your weight, such as the bottom of the foot. About 1.6 million people in the United States get a diabetic foot ulcer each year.

Doctors often group diabetic foot ulcers into three kinds. They are grouped by whether nerve damage, poor blood flow, or both are present.

What Causes Diabetic Foot Ulcers?

High blood sugar, poor circulation, and nerve damage are the main diabetes-related problems that lead to foot ulcers. Other diabetes-related problems are also linked to ulcers, like deformity, previous ulcers or amputations, and kidney and eye disease. Nerve damage and poor circulation are potential underlying causes. Pressure, rubbing, or a small injury then opens the skin. These causes often work together.

High Blood Sugar

Over time, high blood sugar can damage the nerves and the small blood vessels that feed them. High blood sugar can also slow healing. It can make it harder for your body to fight infection.

Diabetes medicines and other steps for bringing blood sugar down can help keep it in range. Your care team will decide what range is right for you. Strong studies have not yet shown that tighter blood sugar control prevents foot ulcers. But keeping blood sugar in range may help prevent or slow nerve damage, a main cause of foot ulcers.

Poor Circulation

Poor circulation means less blood flows to your feet. One cause is peripheral artery disease. It means the arteries that carry blood to your legs and feet have narrowed.

About half of people with a diabetic foot ulcer have peripheral artery disease. Less blood flow can make it hard for a sore or an infection to heal.

Some daily habits can improve blood flow to your feet. Smoking, on the other hand, can constrict blood vessels and lower blood flow to the feet.

Nerve Damage (Neuropathy)

Nerve damage from diabetes is called diabetic neuropathy. It most often affects the feet and legs. Up to half of people with diabetes have this kind of nerve damage.

Nerve damage can affect the feet in these ways:

• Loss of feeling
• Changes in foot shape
• Dry skin

With less feeling, you may not notice a pebble in your sock, a blister, or a small cut. That injury can then turn into a sore that may get infected.

Nerve damage is the most common cause of diabetic foot ulcers. In a 1999 study at two research centers in the U.S. and U.K., nerve damage helped cause ulcers in nearly four in five people who had one.

Nerve damage can also lead to calluses. A callus is a patch of thick skin that forms where rubbing or pressure repeats. Repeated pressure and a small injury can cause bleeding under a callus and then an ulcer.

In the same study, more than three in five people with ulcers had nerve damage, a small injury, and a change in foot shape together.

Other factors can raise your risk, including:

• A past foot ulcer or amputation
• Kidney disease
• Eye disease from diabetes
• Smoking

People who are Black, Hispanic, or Native American have higher rates of foot ulcers and amputations. So do people with low income.

What Are the Early Signs of a Diabetic Foot Ulcer?

The early signs of a diabetic foot ulcer include a warm spot, a blister, a skin crack, and blood inside a callus. You can often find these signs before you feel any pain. Look for these changes every day:

• A new warm spot on the foot
• A blister or a crack in the skin
• Bleeding under the skin
• A callus with dried blood inside it
• Redness or swelling around a cut or blister
• Drainage on your socks

A warm spot can be the first sign that a blister or ulcer is starting. Your doctor may suggest checking the skin temperature of your feet at home. This can usually be done once per day with a handheld infrared thermometer. A spot that is more than about 4°F (2°C) warmer than the same spot on the other foot can be a warning sign.

A callus with dried blood inside it can be the first sign of a wound under the callus.

What Is an Early Stage Diabetic Foot Ulcer?

An early stage diabetic foot ulcer is a pre-ulcer or a shallow open sore. A pre-ulcer is a high-risk spot on the skin that has not yet opened into an ulcer.

A pre-ulcer can be a blister, a crack in the skin, or bleeding under the skin or inside a callus. On the Wagner scale of ulcer stages, a pre-ulcer is grade 0. A pre-ulcer needs treatment from your care team.

A grade 1 ulcer is a shallow open sore. It does not reach the tendon, joint, or bone. You may see drainage on your sock. You may feel little or no pain.

Call your care team right away about any new open sore, even if it does not hurt. Cover it with a bandage until you are seen.

What Are the Stages of a Diabetic Foot Ulcer?

Doctors can describe the stages of a diabetic foot ulcer with the Wagner scale. It has six grades, numbered 0 to 5.

Doctors may also use other scoring systems to describe a wound. International foot care guidelines now prefer systems such as SINBAD and WIfI, which also account for blood flow and infection.

How Are Diabetic Foot Ulcers Treated?

Diabetic foot ulcers are treated by taking pressure off the sore, removing dead tissue, treating infection, restoring blood flow when needed, and using suitable dressings. Most ulcers can heal when pressure comes off, blood flow is good enough, and any infection is treated.

A podiatrist, a doctor who treats feet, may lead your care team. What to expect your team to do when checking for an ulcer:

• Measure its size and depth
• Look for signs of infection
• Test the feeling in your foot with a thin strand called a monofilament
• Check the pulses in your foot
• Order an X-ray or MRI if a bone infection is suspected

High blood sugar and poor blood flow are part of how diabetes slows healing. Your care team will help you keep your blood sugar in range while the ulcer heals.

Hemoglobin A1C, or A1C, is a blood test that shows your average blood sugar over time. While an ulcer heals, some experts suggest aiming for an A1C below 8%. Studies have not shown a clear link between A1C level and how well ulcers heal, so your care team will set your goal.

Taking Pressure Off the Ulcer

Off-loading means keeping weight and pressure off the ulcer so it can heal. Options can include special shoes, a brace, a cast, a wheelchair, or crutches.

For an ulcer on the bottom of the foot caused by nerve damage, the first choice is usually a knee-high cast or walking boot. The provider fits the boot so you can't take it off. This type of device may not be right if you have a serious infection or very poor blood flow. These devices can lower pressure on the ulcer by as much as 80% to 90% compared with a regular shoe.

Boots you can take off also lower pressure. Ulcers heal less well with them than with devices that stay on.

Even a few minutes of pressure on a healing ulcer can reverse the healing. Follow your care team's plan for how long to stay off the foot.

Removing Dead Tissue

Debridement is the removal of dead skin and tissue from an ulcer. A trained provider must do it. Do not try to remove tissue yourself.

The ulcer may look bigger and deeper after debridement.

Treating Infection

About half or more of diabetic foot ulcers become infected. Up to about one in five moderate or severe infections ends in an amputation.

Antibiotics are medicines that treat infections caused by bacteria. Not every ulcer is infected. Doctors use antibiotics when an ulcer shows signs of infection.

A mild infection may be treated with antibiotic pills plus wound cleaning and debridement. A deep or spreading infection needs an urgent check to see if surgery is needed. Antibiotics may be given through a vein at first. If bone is infected, treatment may include surgery.

Restoring Blood Flow

A wound needs enough blood flow to heal. Tests can measure blood flow in the foot and toes.

If tests show poor circulation, your care team should refer you quickly to a vascular specialist. A vascular specialist is a doctor who treats blood vessel disease. If a blockage is found, a procedure to open or bypass the artery may be needed.

Dressings and Other Treatments

Dressings keep the wound covered and moist. A covered, moist wound heals better than one left open to the air.

If an ulcer has not shrunk by about half after four weeks of good care, doctors may consider other treatments. These can include wound vacuum therapy, skin substitutes, or oxygen applied to the wound.

Hyperbaric oxygen is oxygen given in a pressurized chamber. Evidence that it helps foot ulcers heal is limited. Guidelines suggest it may be considered for some ulcers with poor blood flow that have not healed with regular treatment.

Surgery

Surgery may relieve pressure points, correct a change in foot shape, or remove infected bone. Most foot ulcers without infection are treated without surgery.

How Do You Care for a Foot Ulcer at Home?

You care for a foot ulcer at home by following your care team's plan and schedule. Home care can include these steps:

• Keep your blood sugar, blood pressure, and cholesterol in the ranges your doctor sets.
• Keep pressure off the ulcer exactly as your care team advises.
• Use the shoe, cast, or device you were given.
• Keep the ulcer clean and covered with a bandage.
• Keep the dressing and the skin around it dry.
• Change the bandage on the schedule your care team sets.
• Do not remove dead tissue yourself.
• Do not walk barefoot unless your care team says it is OK.
• Check inside your shoes for pebbles or rough spots before you put them on.
• Do not soak your foot.
• Do not put harsh liquids such as hydrogen peroxide on the wound unless your care team tells you to.
• Do not smoke.

When Should You Call a Doctor?

Call your care team right away if you notice any of these signs:

• A new open sore, even if it does not hurt
• A cut, blister, or bruise that does not start to heal after a few days
• Redness, warmth, or swelling around a wound
• More drainage, pus, or a bad smell
• More pain or more firmness around the wound
• An ulcer that looks very white, blue, or black
• A callus with dried blood inside it
• A red, warm, swollen foot with no open sore and nerve damage

Get emergency care right away if a foot wound turns black and smells bad. These can be signs of gangrene, which can be a surgical emergency. Call your care team right away if a foot wound comes with fever, chills, or feeling very ill. These can be signs of a severe infection that may need hospital care.

How Can You Prevent Diabetic Foot Ulcers?

Daily foot checks, good foot care, and regular foot exams can help prevent diabetic foot ulcers. They cannot prevent every ulcer.

Check your feet every day. A good time is each evening when you take off your shoes. Look at the tops, the soles, and between the toes. Use a mirror if you cannot see the soles.

If you care for someone who cannot see or reach their feet, do the check for them. Tell their care team as soon as possible about any cut, blister, crack, or red spot.

Daily foot care includes these steps:

• Wash your feet every day in warm, not hot, water.
• Test the water first. Water at 90°F to 95°F is safe.
• Do not soak your feet.
• Dry your feet well, especially between the toes.
• Put lotion on the tops and soles, but not between the toes.
• Trim your nails straight across.
• Have a foot doctor trim your nails if you cannot see, feel, or reach your feet.
• Do not cut corns or calluses yourself.
• Do not use corn removers.
• Wear clean socks and shoes that fit well.
• Wear shoes and socks whenever you walk or stand, even indoors.
• Keep your feet away from heaters, open fires, and heating pads.

These steps help keep blood flowing to your feet:

• Put your feet up when you sit.
• Wiggle your toes and move your ankles.
• Avoid tight socks.
• Be active as your doctor advises.
• Do not smoke.

Get a full foot exam at least once a year. The exam should check the feeling and the pulses in your feet. Take off your shoes and socks at every visit so your feet get checked.

Your care team should look at your feet at every visit if you have lost feeling or have had an ulcer. Your risk level depends on factors such as lost feeling, poor circulation, foot shape changes, and past ulcers.

Foot care guidelines suggest this exam schedule by risk level:

• Very low risk, once a year
• Low risk, every six to 12 months
• Moderate risk, every three to six months
• High risk, every one to three months

If you are at high risk, your care team may recommend therapeutic shoes. Therapeutic shoes are special shoes or inserts that reduce pressure on the foot. Medicare Part B may help pay for special shoes or inserts. For example, they may cover one pair of therapeutic shoes plus inserts each year if you qualify. Check with your plan.

Frequently Asked Questions

What Are the Different Types of Diabetic Foot Ulcers?

The different types of diabetic foot ulcers are neuropathic, ischemic, and neuroischemic. A neuropathic ulcer forms in a foot with nerve damage and normal blood flow, and it often forms where the foot carries weight. An ischemic ulcer forms in a foot with poor blood flow and no nerve damage. A neuroischemic ulcer forms in a foot with both nerve damage and poor blood flow.

Are Diabetic Foot Ulcers Painful?

Diabetic foot ulcers are often not painful because diabetes can reduce feeling in the feet. You may notice drainage on a sock, redness, or swelling before you feel pain. Any new sore still needs a call to your care team right away, even if it does not hurt.

How Long Does a Diabetic Foot Ulcer Take to Heal?

A diabetic foot ulcer can take weeks or several months to heal. With treatment, about three or four in 10 ulcers heal within 12 weeks. Nearly one in four people still has an open ulcer after a year.

Can a Diabetic Foot Ulcer Come Back?

A diabetic foot ulcer can come back after it heals, in the same spot or in a new spot on either foot. About four in 10 people get another foot ulcer within a year after one heals. About two in three get one within five years. Regular foot exams, good foot care, and therapeutic shoes for high-risk feet can help lower the chance of return.

Sources

• Definition and how common: IWGDF Definitions and Criteria, 2023; Armstrong et al., JAMA, 2023; MedlinePlus Diabetes Foot Ulcers, 2026; APMA Diabetic Wound Care
• Causes and risk factors: NIDDK Peripheral Neuropathy, 2018; CDC Your Feet and Diabetes, 2024; NIDDK Diabetes and Foot Problems, 2017; ADA Standards of Care, Section 12, 2026; IWGDF Practical Guidelines, 2023; NHLBI Peripheral Artery Disease, 2022; Reiber et al., Diabetes Care, 1999
• Early signs and stages: NIDDK Diabetes and Foot Problems, 2017; IWGDF Definitions and Criteria, 2023; Wang et al., World J Diabetes, 2022; IWGDF Classification Guideline, 2023
• Treatment: ADA Standards of Care, Section 12, 2026; Armstrong et al., JAMA, 2023; IWGDF Practical Guidelines, 2023; MedlinePlus Diabetes Foot Ulcers, 2026; APMA Diabetic Wound Care; NIDDK The A1C Test and Diabetes, 2018; IWGDF Offloading Guideline, 2023; IWGDF Wound Healing Guideline, 2023
• Home care and warning signs: MedlinePlus Diabetes Foot Ulcers, 2026; NIDDK Diabetes and Foot Problems, 2017; APMA Diabetic Wound Care; ADA Standards of Care, Section 12, 2026; IWGDF Practical Guidelines, 2023
• Prevention, healing, and recurrence: NIDDK Diabetes and Foot Problems, 2017; CDC Your Feet and Diabetes, 2024; IWGDF Practical Guidelines, 2023; ADA Standards of Care, Section 12, 2026; Armstrong et al., JAMA, 2023; Medicare.gov Therapeutic Shoes or Inserts

This article is general information, not medical advice.