Diabetic Foot Problems

Why diabetes causes foot problems

Three changes work together. Each one alone is manageable. Combined, they let a small injury turn into a deep wound.

• Nerve damage (diabetic peripheral neuropathy): years of high blood sugar damage the long nerves to the feet first. You lose the protective feeling that would make you limp on a blister or take off a tight shoe. Nerve damage also dries the skin (less sweating) and weakens small foot muscles, which pulls the toes into claw shapes.
• Poor circulation (peripheral artery disease): narrowed leg arteries bring less oxygen to the skin. Wounds heal slowly and infection fights back harder.
• Weaker defense against infection: high glucose impairs white blood cells, so bacteria spread faster and with fewer warning signs.

For a focused overview of ulcers and Charcot foot, see our page on diabetic foot. This page walks through the full range of problems, from minor to severe, and how to recognize each.

Types of diabetic foot problems

Skin and nail problems

Dry skin is the earliest and most common change. Deep heel cracks can bleed and become infected. Calluses and corns form where bone presses against the shoe. In diabetes, bleeding under a callus (it turns dark or bruised-looking) often means an ulcer is forming beneath it and needs a professional to pare it down. Athlete's foot and fungal nail infection are more common and more important in diabetes because they break the skin barrier.

Ulcers

A diabetic foot ulcer is a wound through the full skin layer. Neuropathic ulcers sit on pressure points: the ball of the foot, the tips of clawed toes, the heel. They often have a ring of callus and do not hurt. Ischemic ulcers from poor blood flow appear on the toe tips and edges of the foot, look pale, and are often painful. Many ulcers are both.

Infection

Foot infections range from mild skin redness around a wound to deep abscesses. Signs can be muted. A foot that suddenly makes blood sugar rise for no other reason may be infected. If a probe or swab can reach bone through an ulcer, or an ulcer does not heal, doctors check for osteomyelitis (bone infection).

Charcot foot

In Charcot neuroarthropathy, the numb foot's bones weaken and fracture with ordinary walking. Early on, the foot is warm (often more than 2°C, about 4°F, warmer than the other foot), red and swollen, sometimes with only mild ache. If you keep walking on it, the arch collapses into a "rocker-bottom" shape. Early immobilization in a cast prevents most of this deformity, so a hot swollen foot in someone with neuropathy needs same-day assessment.

Early signs to check for every day

Use a mirror or ask someone to help if you cannot see the soles of your feet. Look for:

• Cuts, blisters, splinters or puncture marks
• Red areas, especially ones that stay red after you take off your shoes
• Swelling or one foot warmer than the other
• Calluses that have darkened or have blood in them
• Moisture, peeling or cracks between the toes
• Discharge on your socks
• New changes in foot shape

Signs of nerve damage in the feet include numbness in the feet, pins and needles, burning feet at night, and not feeling the floor well. Signs of poor circulation include calf cramps when walking, cold feet, shiny hairless skin and weak pulses.

Who is most at risk

Risk rises sharply with:

• Loss of protective sensation on a monofilament test
• Absent foot pulses or known peripheral artery disease
• A previous ulcer or amputation (the strongest predictor of a new ulcer)
• Foot deformity or thick calluses
• Smoking
• Kidney failure, especially on dialysis
• Poor vision, which makes self-checks hard
• Long duration of diabetes and high A1C levels

How doctors check your feet

A foot exam should happen at least once a year for everyone with diabetes, and at every visit if you are high risk. It includes:

1. Skin and nail inspection between the toes and on the soles.
2. Monofilament test: a nylon filament pressed on several sites. Not feeling it means loss of protective sensation.
3. Vibration test with a tuning fork and checking ankle reflexes.
4. Pulses at the top of the foot and inner ankle, and often an ankle-brachial index (ABI) to compare blood pressure in the ankle and arm.
5. Footwear check for fit, wear patterns and pressure.

For a wound, doctors may add X-rays, an MRI for bone infection or Charcot changes, blood tests and a deep tissue sample for culture.

Treatment

Minor problems

• Dry skin: a urea-based or plain moisturizer once or twice a day, avoiding between the toes.
• Calluses and corns: have a podiatrist trim them. Do not cut them yourself or use corn plasters, which contain acid that can burn numb skin.
• Fungal infections: antifungal creams for the skin. Nail infections may need prescription treatment.
• Ingrown nails: see a podiatrist rather than digging out the nail edge.

Ulcers and infection

Treatment focuses on taking pressure off the wound (offloading with a total contact cast or removable boot), removing dead tissue (debridement), keeping the wound moist and clean, controlling infection with antibiotics, and restoring blood flow with angioplasty or bypass when arteries are blocked. Good glucose control speeds healing. A specialist diabetic foot team gives the best results.

Charcot foot

Immobilization in a cast or boot until the heat and swelling settle, often for several months, followed by custom shoes. Surgery is used for unstable or severely deformed feet.

Prevention

• Check your feet daily and wash them in warm, not hot, water. Test the water with your elbow because numb feet cannot judge heat.
• Never walk barefoot, indoors or out, including at the beach.
• Wear shoes that fit with room for your toes, and check inside them for stones before putting them on.
• Wear clean socks without thick seams. Avoid tight elastic tops.
• Avoid heating pads, hot water bottles and soaking feet.
• Cut toenails straight across, or have a podiatrist do it.
• Stop smoking, and keep blood sugar, blood pressure and cholesterol on target.
• Ask about prescription diabetic shoes or insoles if you have neuropathy or deformity.

Frequently asked questions

What are the early signs of diabetic foot problems?

Early signs include numbness, tingling or burning in the toes, dry cracked skin, calluses that darken, cold feet, and small cuts or blisters you did not feel happening. A foot that looks red or swollen, or is warmer than the other one, needs prompt attention even without pain.

Why are foot problems so serious in diabetes?

Nerve damage means you may not feel an injury, poor circulation slows healing, and high blood sugar weakens the immune response. A painless blister can therefore become an infected ulcer within days. Diabetes is a leading cause of lower-limb amputation, and most amputations start with a foot ulcer.

Can diabetic foot problems be reversed?

Some can. Calluses, dry skin and fungal infections clear with treatment, and most ulcers heal with offloading and wound care. Nerve damage is usually permanent, though good glucose control can slow it. Charcot deformity cannot be undone, which is why catching the early warm, swollen stage matters.

How often should someone with diabetes see a podiatrist?

Everyone with diabetes needs a foot check at least once a year. If you have neuropathy, poor circulation, deformity or a past ulcer, you may need a podiatrist every 1 to 3 months. Anyone with an active ulcer should be seen by a specialist foot team.

Should people with diabetes soak their feet?

No. Soaking dries and softens the skin, making cracks and infection more likely, and numb feet can be scalded without warning. Wash your feet briefly in warm water, dry them well, especially between the toes, and moisturize the tops and soles.