Diabetic Foot Ulcer

A diabetic foot ulcer is a break in the skin of the foot that fails to heal in the normal way. Two problems drive it, and most people who develop one have both.

The first is nerve damage. Years of raised blood glucose damage the nerves in the feet, so pressure, heat and injury stop registering. Pain is the signal that makes a person limp, change shoes or stop walking, and without it an injury is walked on for days. The nerves that keep the skin supple are affected too, so the skin dries and cracks, and the small foot muscles weaken, changing the shape of the foot and putting weight through places it was never meant to go.

The second is blood supply. The arteries below the knee narrow, and healing a wound needs more blood than resting skin does. A foot that manages perfectly well while intact cannot repair itself once broken.

Ulcers start from something small: a new pair of shoes, a crack in dry heel skin, a stone inside a sandal, walking barefoot on a hot floor, a burn from hot water, or a cut taken while trimming a nail. Raised glucose also blunts the body's response to infection, so bacteria spread further and faster than they would otherwise.

Your doctor examines the whole foot, not just the wound, with both shoes and socks off and with the other foot checked in the same detail. They look between the toes, along the sole, at the heel and around the nails, since ulcers hide in all of those places.

They will measure the wound and, importantly, probe its depth. What they are establishing is how far down it goes and whether bone can be felt at the base, because a wound reaching bone is a different problem from one in the skin, and depth matters far more than width.

Sensation is tested with a fine nylon filament pressed at set points on the sole and with a tuning fork, which shows how much protective feeling has been lost. Your doctor then feels the pulses at the ankle and the top of the foot, and usually measures the pressure in the leg arteries, since a wound cannot heal on a blood supply that is inadequate and finding that out early changes the whole plan.

They will look for spreading redness, warmth, swelling, discharge and smell, check your glucose control, and look inside your footwear for the object or the seam that caused it.

Healing is measured in months and it asks more of you than of anyone else.

A shallow ulcer on a foot with a good blood supply commonly heals in six to twelve weeks. A deep one, or one on a foot whose blood supply has to be improved first, takes three to six months, and sometimes longer. Where bone is involved, add weeks of antibiotic treatment to that.

The single thing that decides the timetable is keeping weight off the wound. An ulcer on the sole heals while you stay off it and stops healing the moment you walk on it, and because it does not hurt, walking on it feels harmless. Whatever device your team provides to take the load has to be worn for every step, including the short trips inside the house at night.

Dressings are changed every two to three days and the wound is reviewed every one to two weeks. Blood glucose control, stopping smoking and good nutrition all measurably affect healing speed.

Once it has healed, the work continues. Protective footwear, daily inspection of both feet including between the toes and with a mirror for the soles, and regular foot checks are lifelong, because a foot that has ulcerated once frequently ulcerates again within a year.