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

Diabetic foot ulcers are staged by how deep the wound goes, from an intact but at-risk foot (Wagner grade 0) to a superficial skin break (grade 1), a deeper wound into the tissue under the skin (grade 2), exposed bone or tendon (grade 3), partial-foot gangrene (grade 4) and whole-foot gangrene (grade 5). Clinicians most often use the Wagner Scale, while a simpler four-stage breakdown (pre-ulcer, superficial, deep, infected or gangrenous) helps patients recognize what they are looking at. About 15% of people with diabetes will develop a foot ulcer at some point, and the earlier a wound is caught and staged, the more likely it is to heal without surgery or amputation.

Key Takeaways

• The Wagner Scale grades diabetic foot ulcers from 0 to 5 based on depth, infection and gangrene. Grade 0 is skin that is still intact but at high risk; grade 5 is gangrene of the whole foot.
• A simpler four-stage view runs from pre-ulcerative lesions (calluses, corns, fissures, redness) to superficial ulcers, deep ulcers, and infection or gangrene.
• Diabetic foot ulcers start with nerve damage and poor circulation. Diabetic peripheral neuropathy hides injuries, and vascular insufficiency slows healing.
• Early-stage ulcers usually heal with cleaning, proper dressings and offloading pressure, all directed by a clinician. Deep or infected ulcers need urgent professional care.
• Prevention is daily: inspect your feet, keep them clean and moisturized (not between the toes), wear well-fitting shoes and non-binding diabetic socks, and keep blood sugar in range.
• Any open sore on a diabetic foot is a same-day call to your podiatrist, even if it does not hurt.

What are the stages of a diabetic foot ulcer?

The stages of a diabetic foot ulcer describe how deep the wound has gone and whether infection or tissue death is present. Medical professionals most often classify them using the Wagner Scale, which runs from grade 0 (no open ulcer) to grade 5 (gangrene of the entire foot). To manage diabetic foot ulcers effectively, it's essential to understand the various stages they progress through:

Medical professionals monitor diabetic foot ulcers using the above classification and may modify treatment strategies accordingly. Early detection and prompt intervention are crucial to preventing complications and improving ulcer healing. If you want to see what the earliest grades look like on real feet, our guide to early-stage diabetic foot ulcer pictures walks through them.

What causes diabetic foot ulcers and who is at risk?

Diabetic foot ulcers are caused by the combination of nerve damage, reduced blood flow and repeated pressure on skin that cannot feel or repair itself normally. At the root of diabetic foot ulcers is the chronic high blood sugar characteristic of diabetes, which can damage nerves, blood vessels, and various tissues over time. This damage often results in diabetic peripheral neuropathy and vascular insufficiency, impairing sensation and circulation in the feet. Consequently, people with diabetes are more susceptible to foot injuries and infections, as well as slower wound healing. Diabetic foot ulcers affect around 15% of people with diabetes throughout their lifetime, and they can significantly impact a person's quality of life and may even lead to amputation if left untreated.

Common risk factors for developing diabetic foot ulcers include:

• Poor blood sugar control: This increases the likelihood of developing neuropathy and blood vessel damage.
• Neuropathy: A loss of feeling in the feet can lead to unnoticed injuries, increasing the risk of ulcers.
• Blood flow problems: Poor circulation impairs the body's ability to fight infections and heal wounds.
• Foot deformities: Structural abnormalities can cause pressure points, contributing to the formation of ulcers.
• Improper footwear: Tight or ill-fitting shoes can cause friction, leading to skin breakdown and ulcers.

What does each stage of a diabetic foot ulcer look like?

Each stage of a diabetic foot ulcer has recognizable features, moving from skin changes with no open wound to a shallow sore, then a deep wound, and finally infection or dead tissue. We've put together an easy-to-follow breakdown of the stages, so you can recognize possible symptoms and take action, if necessary. Diabetic foot ulcers can be classified into four stages:

• Stage 1: Pre-ulcerative lesions
• Stage 2: Superficial ulcers
• Stage 3: Deep ulcers
• Stage 4: Infections and gangrene

Each stage progresses from mild to severe, and we'll briefly describe the characteristics of each one.

Stage 1: Pre-ulcerative lesions

A stage 1 (pre-ulcerative) lesion is skin that is damaged or under pressure but not yet open. In this stage, dermatological changes occur, such as callus formation, fissures, or corns, which can increase pressure points and decrease the skin's protective barrier. Indicative symptoms might include:

• Redness
• Warmth to touch
• Swelling

If you notice these features, it's important to take preventive steps, such as wearing specialized diabetic socks and seeking medical advice. Never trim a callus or corn yourself; a podiatrist can reduce it safely.

Stage 2: Superficial ulcers

A stage 2 (superficial) ulcer is a shallow open wound that involves only the skin. When small breaks or wounds in the skin surface appear, we've entered Stage 2. These superficial ulcers can be shallow and painful but might not display signs of infection, and because of neuropathy they may not hurt at all. Care for these, directed by your podiatrist or wound clinic, includes:

• Cleaning the area gently
• Applying appropriate dressings
• Offloading pressure (using shoe inserts, for instance)

With prompt treatment, these ulcers can heal and prevent further complications.

Stage 3: Deep ulcers

A stage 3 (deep) ulcer extends beneath the skin into fat, muscle, tendon or bone. Deep ulcers reach through the subcutaneous tissue, and may involve the muscle, tendon, or bone. This stage presents an increased risk for diabetic foot infection, and the following symptoms might be present:

• Foul odor
• Discharge from the wound
• Tunneling or undermining of the wound edges

In Stage 3, professional medical care is necessary to assess and treat the ulcer appropriately, as well as monitoring for any signs of infection.

Stage 4: Infections and gangrene

A stage 4 ulcer involves established infection, dead tissue, or both, and carries the highest risk of amputation. The final stage is the most severe and poses a significant risk for amputation. At this point, the ulcer may display:

• Necrotic tissue
• Abscesses
• Osteomyelitis (bone infection)

Immediate medical intervention and treatment are crucial to minimize the risk of limb loss. Read more about diabetic foot gangrene treatment.

The following table shows the key characteristics of each stage:

How does a diabetic foot ulcer heal, and how long does it take?

A diabetic foot ulcer heals when the wound is kept clean, pressure is taken off it, infection is controlled, and enough blood and oxygen reach the tissue, which is why healing time depends more on circulation, blood sugar and offloading than on the dressing itself. Superficial (Wagner grade 1) ulcers that are offloaded early often close within weeks; deeper or infected ulcers can take months and may need debridement (removal of dead tissue), antibiotics, special footwear or a cast, or procedures to restore blood flow. Your care team will measure the wound at each visit; a wound that is not getting smaller after a few weeks of treatment is a signal to re-check circulation and infection.

How can you prevent diabetic foot ulcers and keep them from getting worse?

Preventing diabetic foot ulcers comes down to a daily routine of hygiene, foot inspection, protective footwear, blood sugar management and pressure relief. By being proactive and following some simple steps, we can help prevent and properly manage diabetic foot ulcers, promoting quicker healing and reducing the risk of complications. Our guide to taking good care of your diabetic feet covers the full routine.

Foot hygiene

Maintaining proper foot hygiene is crucial. We should:

• Clean our feet daily with mild soap and warm (never hot) water
• Dry our feet thoroughly, paying special attention to the spaces between our toes
• Apply a skin moisturizer daily to prevent dryness and cracking (but avoid applying it between our toes)

Appropriate footwear

We can protect our feet by wearing appropriate footwear. Factors to keep in mind include:

• Opting for shoes that fit well, while avoiding too tight or too loose shoes
• Choosing footwear that provides even weight distribution and good arch support
• Wearing socks designed for diabetic patients, and never going barefoot, even indoors

Daily foot inspection

It's important to inspect our feet daily. We should look for:

• Redness, swelling, or warmth
• Calluses or corns
• Cuts, blisters, or any open sores

If we detect any unusual symptoms or signs of an ulcer, it's crucial to consult with a medical professional immediately for proper treatment.

Blood sugar management

Another factor to consider is blood sugar management. We can improve our diabetes management by:

• Monitoring our blood sugar levels regularly (why checking your blood sugar matters)
• Following a balanced meal plan
• Exercising on a regular basis under the guidance of a healthcare professional

Pressure relief

Finally, we need to be cautious about pressure relief. Our feet tend to handle a lot of pressure, which can cause ulcers over time. To reduce this pressure, we can:

• Change our position frequently, especially if we sit or stand for extended periods
• Use padding or cushions on chairs or in shoes for optimal support and comfort
• Elevate our feet whenever possible to improve circulation

By following these practical tips, we're taking essential steps towards protecting our feet and preventing diabetic foot ulcers. Remember, consistency and vigilance in our foot care routine are key to staying one step ahead of complications.

Can diabetic socks help with diabetic foot ulcers?

Diabetic socks help by protecting intact skin so an ulcer is less likely to start; they are not a treatment for an open wound, and an existing ulcer should only be covered with the dressing your clinician prescribes. For a foot at Wagner grade 0 or with pre-ulcerative changes, a good diabetic sock reduces friction with a seamless toe, wicks moisture so skin stays dry, cushions pressure points, and has a non-binding top that does not restrict blood flow to the foot. For a detailed comparison, see our guide to diabetic socks vs. compression socks.

CircuFiber diabetic socks go a step further. The fabric is woven with Circulight® IR fibers containing thermoreactive mineral particles that absorb your own 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.

What this means in practice: wear them on feet with intact skin as part of your daily prevention routine. If you already have an open ulcer, ask your podiatrist what to wear over the dressing and offloading device; do not put any sock directly over a wound without that guidance.

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

See a podiatrist the same day you notice any open sore, blister, cut or crack on a diabetic foot, even if it is small and painless, because neuropathy can hide how serious it is. Seek urgent care for redness spreading from a wound, warmth, swelling, foul odor, drainage, black or dead-looking tissue, fever, or a sudden rise in blood sugar, all of which can signal infection or gangrene. If you have not yet been diagnosed with an ulcer, a yearly diabetic foot exam (more often if you have neuropathy or poor circulation) is how early-grade problems get caught. Not sure who to call? Read our guide to choosing a diabetic foot specialist.

Frequently asked questions about diabetic foot ulcer stages

What does a stage 1 diabetic foot ulcer look like?

A stage 1 (pre-ulcerative) diabetic foot ulcer is not yet an open wound. It looks like a thick callus, corn or crack, often with redness, warmth or swelling over a pressure point such as the ball of the foot, the heel or the tip of a toe. On the Wagner Scale, an actual shallow open sore involving only the skin is grade 1.

What is the Wagner classification of diabetic foot ulcers?

The Wagner classification grades diabetic foot ulcers from 0 to 5 by depth and tissue loss: 0 is intact skin at high risk, 1 is a superficial ulcer, 2 reaches the subcutaneous tissue, 3 exposes bone, tendon or joint capsule, 4 is partial-foot gangrene, and 5 is gangrene of the whole foot. Clinicians use it to track progression and choose treatment.

What are the healing stages of a diabetic foot ulcer?

A diabetic foot ulcer heals in the same broad sequence as other wounds: inflammation and cleaning, then new tissue filling the base, then the edges closing and the skin remodeling. In practice, healing depends on offloading pressure, controlling infection, removing dead tissue, good blood flow and good blood sugar control, so your care team measures the wound regularly to confirm it is shrinking.

How long does a diabetic foot ulcer take to heal?

Superficial ulcers that are caught early and offloaded properly often close in a few weeks, while deep or infected ulcers can take several months and may need surgery or procedures to improve circulation. A wound that is not shrinking after a few weeks of treatment needs a re-evaluation of blood flow and infection.

Can a diabetic foot ulcer heal on its own?

A diabetic foot ulcer rarely heals well on its own, because the nerve damage and poor circulation that caused it also slow healing and hide infection. Even a small ulcer should be assessed by a podiatrist, who will clean it, dress it and offload it. Waiting is the most common reason a grade 1 ulcer becomes a grade 3 or 4 ulcer.

What is the difference between a stage 4 and stage 5 diabetic foot ulcer?

On the Wagner Scale, grade 4 means gangrene limited to part of the foot, usually the forefoot or toes, often with bone infection, while grade 5 means gangrene of the whole foot. Both are limb-threatening emergencies; grade 4 may be treated with partial amputation or revascularization, while grade 5 generally requires amputation.

References, studies and sources

• Centers for Disease Control and Prevention (CDC). Diabetes and Your Feet. https://www.cdc.gov/diabetes/library/features/healthy-feet.html
• Mayo Clinic. Diabetic neuropathy: Symptoms and causes. https://www.mayoclinic.org/diseases-conditions/diabetic-neuropathy/symptoms-causes/syc-20371580
• 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/
• 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
• 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.