Diabetic Foot

Why diabetes damages the feet

Nerve damage (neuropathy)

High blood sugar over years damages nerves, starting with the longest ones, in the feet. Diabetic peripheral neuropathy causes:

• loss of feeling for pain, heat and pressure
• dry, cracked skin (from damage to sweat gland nerves)
• weak foot muscles that cause clawed toes and high-pressure spots

Without pain, a stone in a shoe or a tight shoe can rub a hole in the skin without being noticed.

Poor blood flow

Peripheral artery disease is more common and more severe in diabetes. It slows healing, makes infection harder to fight, and in severe cases leads to tissue death.

Infection

High blood sugar impairs immune defenses. Infection can spread from an ulcer to deep tissues and bone (osteomyelitis).

Types of diabetic foot problems

Early signs of diabetic foot problems

• numbness, tingling, burning or "walking on cotton wool" feeling
• dry, cracked skin, especially on the heels
• calluses, corns and blisters
• color changes: red, pale, blue or dark spots
• swelling or warmth in one foot
• cuts or sores that are slow to heal
• calf pain when walking (claudication)
• changes in foot shape

Diagnosis and risk assessment

The American Diabetes Association recommends a comprehensive foot exam at least once a year for everyone with diabetes, and at every visit for those at high risk. It includes:

• inspection of skin, nails, shape and footwear
• testing sensation with a 10-gram monofilament and a tuning fork
• checking foot pulses, and an ankle-brachial index test if pulses are weak or there are symptoms

For wounds, clinicians measure the ulcer, probe to see if bone is reachable, take samples for culture if infected, and order X-rays or MRI to check for bone infection or Charcot changes. Vascular studies assess blood flow.

Treatment

Ulcers

• Offloading: removing pressure is the most important treatment. A total contact cast or a removable cast walker is often used for ulcers on the sole.
• Debridement: removing dead tissue and callus.
• Dressings: keeping the wound moist and clean.
• Blood sugar control.
• Restoring blood flow: angioplasty or bypass surgery if circulation is poor.

Infections

Mild infections can be treated with oral antibiotics. Moderate to severe infections, or bone infection, need intravenous antibiotics, hospital care, and often surgical drainage or removal of infected bone.

Charcot foot

Immediate offloading in a cast for months until the inflammation settles, followed by custom footwear. Surgery is used for severe deformity.

Amputation

Partial foot or leg amputation is sometimes needed for gangrene, overwhelming infection or non-healing wounds. Multidisciplinary foot care teams have reduced amputation rates substantially.

Daily foot care and prevention

• Check your feet daily, including soles and between toes. Use a mirror or ask someone to help.
• Wash daily in lukewarm water (test with your elbow), dry well between the toes.
• Moisturize dry skin, but not between toes.
• Never walk barefoot, even at home or on the beach.
• Wear well-fitting shoes and check inside them for objects before putting them on. Choose socks without thick seams.
• Cut nails straight across, or have a podiatrist do it.
• Do not treat corns or calluses yourself with blades or chemical corn removers.
• Avoid heating pads and hot water bottles on numb feet.
• Control blood sugar, blood pressure and cholesterol.
• Stop smoking, which worsens circulation.
• See a podiatrist regularly if you have neuropathy, deformity or a past ulcer.

Frequently asked questions

What are the early signs of diabetic foot problems?

Early signs include numbness, tingling or burning, dry cracked skin, calluses, blisters, color changes, swelling and cuts that heal slowly. Because nerve damage removes pain, any new mark or change on the foot should be checked promptly.

What does a diabetic foot ulcer look like?

It is an open sore, often round, usually on the ball of the foot, under the big toe or on the toes, sometimes with a ring of thick callus. It may drain fluid onto your sock and is often painless. Redness, swelling or smell suggest infection.

What is Charcot foot?

Charcot foot is a complication of diabetic neuropathy in which the bones of the foot weaken, fracture and collapse, often after minor injury. It begins as a warm, red, swollen foot with little pain. Early casting prevents severe deformity.

How often should people with diabetes have a foot exam?

Everyone with diabetes should have a comprehensive foot exam at least once a year. People with neuropathy, poor circulation, deformities or previous ulcers need checks at every visit. Daily self-checks at home are also essential.

Can diabetic foot ulcers heal?

Yes. Many ulcers heal within weeks to months with pressure offloading, wound care, infection treatment, good blood sugar control and improved blood flow. Ulcers often return, so protective footwear and regular podiatry follow-up after healing are important.