Diabetic Foot Infection
Infection of the foot in people with diabetes, often from an ulcer
Quick Facts
- Type: Infection / diabetes complication
- Often starts in: A foot ulcer or break in the skin
- Warning signs: Redness, swelling, warmth, pus, fever
- Why serious: Can spread to bone; risk of amputation
Overview
A diabetic foot infection is an infection involving the skin, deeper tissues, or bone of the foot in someone with diabetes. It usually begins where the skin is broken, most often in a diabetic foot ulcer, allowing bacteria to enter. Because diabetes can damage nerves and reduce blood flow to the feet, these infections can develop without much pain and can spread faster and heal more slowly than in people without diabetes.
Diabetic foot infections range from mild skin infections to deep, serious infections that reach the bone or spread through the body. They are a leading cause of hospital admissions and amputations in people with diabetes, so early recognition and prompt treatment are vital. With good diabetes control and careful foot care, many infections can be prevented or caught early.
Symptoms
Signs of a diabetic foot infection may be less obvious than usual because nerve damage can blunt pain. Watch for:
- Redness, warmth, and swelling around a wound or area of the foot
- Pus, drainage, or a bad smell from a wound
- A foot ulcer that is enlarging, not healing, or changing in appearance
- Increasing pain, although pain may be reduced if nerves are damaged
- Skin that is darkening, blistering, or breaking down
- Fever, chills, or feeling generally unwell, which suggest a more serious infection
- High blood sugar levels that are harder to control than usual
Any of these signs, especially fever, spreading redness, or a foul-smelling or rapidly worsening wound, should be assessed urgently.
Causes
Diabetic foot infections develop when bacteria enter through broken skin and the body's defenses are weakened by diabetes. Key factors include:
- Foot ulcers and skin breaks: The most common entry point for bacteria.
- Nerve damage (neuropathy): Reduced sensation means injuries and pressure sores go unnoticed and untreated.
- Poor circulation: Reduced blood flow slows healing and the delivery of infection-fighting cells.
- High blood sugar: Impairs the immune system's ability to fight infection.
- Foot deformities and pressure points: Areas of repeated pressure or rubbing that break down.
Once bacteria take hold, infection can spread from the skin into deeper tissue and bone, sometimes within days.
Risk Factors
- Poorly controlled blood sugar
- Existing foot ulcers or a history of foot ulcers
- Nerve damage with loss of feeling in the feet
- Poor circulation or peripheral artery disease
- Foot deformities, calluses, or pressure areas
- Smoking, which worsens circulation
- Poorly fitting footwear and walking barefoot
Diagnosis
Diagnosis combines examination of the foot with tests to judge the depth and severity of infection.
- Examination: Assessing the wound, surrounding skin, signs of infection, sensation, and blood flow.
- Wound cultures: Samples to identify the bacteria and which antibiotics will work.
- Blood tests: To detect infection, inflammation, and blood sugar control.
- Imaging: X-rays, MRI, or other scans to check whether the infection has reached the bone (osteomyelitis).
- Probing the wound: To assess how deep it goes.
Determining whether bone is involved is especially important, as it changes the length and type of treatment.
Treatment
Treatment aims to clear the infection, help the wound heal, and prevent it from spreading or recurring. It often involves several specialists.
- Antibiotics: Chosen to match the bacteria; mild infections may be treated with oral antibiotics, while serious ones need intravenous treatment in hospital.
- Wound care: Regular cleaning, dressing, and removal of dead or infected tissue (debridement).
- Offloading pressure: Special footwear, casts, or devices to take weight off the wound so it can heal.
- Improving blood flow: Treatment of poor circulation, sometimes with a procedure to restore blood supply.
- Blood sugar control: Tightening diabetes management to support healing and immunity.
- Surgery: To drain abscesses, remove infected bone, or, in severe cases, amputate part of the foot to save the rest of the limb and life.
Prompt, thorough treatment greatly improves the chance of healing and reduces the risk of amputation.
Prevention
- Check your feet every day for cuts, blisters, redness, or swelling
- Keep blood sugar well controlled
- Wash and dry feet carefully and moisturize dry skin (but not between the toes)
- Wear well-fitting shoes and never walk barefoot
- Have regular foot checks by a healthcare professional
- Treat any cut, blister, or sore promptly and seek help if it does not heal
- Stop smoking to improve circulation
When to See a Doctor
Contact your healthcare team promptly if you have diabetes and notice any wound, redness, swelling, or drainage on your foot, or a sore that is not healing. Seek emergency or urgent care if you have:
- Fever, chills, or feeling very unwell along with a foot wound
- Redness spreading rapidly up the foot or leg
- A foul-smelling wound, black or dying tissue, or pus
- Sudden increase in pain, swelling, or a wound that is rapidly worsening
Early treatment can prevent serious complications, including the spread of infection and amputation.
Frequently Asked Questions
Why are foot infections more dangerous in people with diabetes?
Diabetes can damage the nerves and reduce blood flow to the feet, so injuries may go unnoticed and heal slowly, and high blood sugar weakens the immune system. As a result, infections can spread quickly and deeply, sometimes reaching the bone, and are a leading cause of amputation.
What are the warning signs I should watch for?
Watch for redness, warmth, swelling, pus or drainage, a bad smell, or a wound that is enlarging or not healing. Fever, chills, feeling unwell, spreading redness, or darkening skin are signs of a serious infection. Because pain may be reduced by nerve damage, do not rely on pain alone.
How is a diabetic foot infection treated?
Treatment includes antibiotics matched to the bacteria, careful wound care and removal of dead tissue, taking pressure off the wound, improving blood flow, and tight blood sugar control. Severe infections may need hospital care, surgery to drain or remove infected tissue, and sometimes amputation to save the limb.
Can diabetic foot infections be prevented?
Many can. Check your feet daily, keep blood sugar well controlled, wear well-fitting shoes, never walk barefoot, care for your skin, and have regular professional foot checks. Treat any cut, blister, or sore promptly and seek help early if it does not heal.
When is a diabetic foot infection an emergency?
Seek urgent care if you have fever or feel very unwell with a foot wound, redness spreading rapidly up the leg, a foul-smelling wound, black or dying tissue, pus, or a wound that is rapidly worsening. Early treatment can prevent the infection from spreading and reduce the risk of amputation.
References
- Centers for Disease Control and Prevention (CDC). Diabetes and your feet.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Diabetic foot problems.
- Mayo Clinic. Diabetic foot care.
- MedlinePlus, U.S. National Library of Medicine. Diabetic foot.