Diabetic foot: tingling, burning and numbness in the legs

Tingling, burning or a numb toe is often where diabetes first shows up in the foot, and where people first lose weeks before getting it properly looked at.

Burning that peaks at night, socks that feel too rough, a blister you never felt - each points at a different problem, and the difference decides the treatment.

Three different problems, three different stories

The foot can be in trouble from the nerves, from the arteries, or from the spine, and the treatment for each is different. Before anything else, work out which one you are dealing with.

• Nerve pattern: tingling, burning, electric shocks or numbness that starts in the toes, sits in both feet in a stocking shape, and is worse at rest and at night. A bedsheet touching the sole can feel painful. Pain often peaks when sugar control has just improved sharply, which frightens people into stopping the medicine that helped.
• Artery pattern: a cramp or heaviness in the calf or buttock that arrives after walking a fairly fixed distance and settles within a few minutes of standing still. The foot may feel cold, look pale on elevation or dusky, lose hair on the shin, and grow thick slow nails. Rest pain in the toes at night, relieved by dangling the leg off the bed, is a warning that the blood supply itself is short.
• Spine pattern: one leg, shooting from the back or buttock down a specific strip of skin, changed by bending, coughing or sitting, sometimes with weakness in the foot. Diabetes does not own every tingling leg, and dropping this one into a sugar explanation delays the right scan.

There is also a fourth cause that people forget: long-standing metformin use can lower vitamin B12, thyroid problems and alcohol both damage nerves, and several other medicines do too. None of these are fixed by foot powder, and some of them are partly reversible if caught early, so they belong in the workup, not after it.

The ninety-second check

Most diabetic foot amputations in this country begin as a small wound the patient never felt. The whole prevention programme is one look per day.

• Same time every evening, after washing, when the light is good. If your eyes or your back will not reach, use a mirror, or let your partner check, or feel with the back of your hand rather than your numb foot.
• Look at the top of the foot, the sole, the heel, between and under the toes, and around the nails. You are hunting for a blister, a crack, a callus with a red or brown dot inside it, a shoe rub mark, a ingrown nail, a spot of dried blood on the sock, warmth in one toe, or a wound you cannot remember getting.
• Wash with lukewarm water and mild soap, dry carefully between the toes, and moisturise the top and sole - never between the toes, where a damp fold turns into a fungal wound.
• Never cut a corn, a callus or an ingrown nail with a blade, a razor, corn-cutter pliers or an over-the-counter acid pad. Filing the nail straight across, with the edge just smoothed, is the limit of what belongs at home. Anything thicker than that is a podiatrist job.
• Do not use a hot water bottle, an electric blanket, a room heater pointed at the feet, or bare feet on sand, tile or a marble floor. A foot that cannot feel heat is a foot that cannot warn you it is burning.

Footwear is part of the prescription

Buy shoes in the evening, when feet are at their largest. Choose a wide, deep toe box that lets the toes sit flat, a firm heel, and a sole thick enough to stop a nail or a stone from reaching the skin. Two pairs of shoes rotated daily last longer and rub less. Socks should be seamless, not too tight at the calf, and changed daily. Before every shoe goes on, put a hand inside it - a staple, a torn lining or a pebble is exactly the kind of thing a numb foot will not report.

Slippers with a strap beat bare feet indoors, and beat walking on tile at night. Driving shoes should be closed and thin-soled enough to feel the pedal; chappals while driving are an accident waiting to happen.

What to ask to be checked

Bring the foot up at your next diabetes review and ask for it to be examined, not just discussed. In clinic that means the pulses at the ankle and foot, a simple filament or tuning-fork test on the sole, a look at the skin and nails, and a comparison of the two feet. Alongside that, vitamin B12, thyroid function, kidney function and haemoglobin, and an honest account of alcohol and of every medicine you take. Nerve conduction studies are useful when the picture is atypical or one-sided; they are not a ticket you must buy before anything can be done.

And the uncomfortable truth: sugar control is the only treatment that changes the course of diabetic nerve damage. Not stopping it. If a medicine is being blamed for the tingling, that conversation happens with the doctor who prescribed it, and until that conversation happens the medicine continues.

When the foot stops being a home matter

These are not wait-and-watch signs. Any one of them means being seen the same day or the next, not after the weekend.

• Any break in the skin that has not clearly improved in a week, or any ulcer, however small, especially under a callus or on the ball of the foot.
• Discharge, a bad smell, a black scab, red streaks moving up the foot, swelling that has started on one side, or fever with any of these.
• A foot that has become warm, swollen and deformed with only mild pain - that is a bone problem inside the foot, and walking on it is what destroys the shape.
• A cold, pale or blue, suddenly painful foot, or a wound where bone or tendon shows.
• New loss of feeling that is climbing up the leg quickly, or new weakness like dropping the foot while walking.

Where we fit in

What we do alongside your diabetes team is the unglamorous half: making the daily check a habit, choosing shoes that fit, keeping the skin on the top and sole conditioned, supporting circulation and strength with walking and light resistance work that a foot can tolerate, keeping protein and calories adequate so a wound has something to heal with, and correcting the two habits that cause the most damage - rubbing and hard massage on a numb foot, and soaking an ulcer because it looks cleaner afterwards. We do not touch prescribed insulin or metformin, we do not dress a deep wound at home, and we do not promise a numb foot its feeling back.

At our two centres, a diabetic foot review starts with the shoes, the nails and the pulses, and with a decision about whether this is a care plan or a referral - and if the skin is broken, that decision is made the same day.

Every individual is different. Before starting any new remedy, oil or routine, please consult a qualified doctor who knows your diabetes treatment, so the plan fits your nerves, your circulation and your medicines as they actually are.