The diabetic foot ulcer: a case-based approach

The presentation

Picture an adult who has lived with diabetes for many years. They notice a sore on the sole of the foot, under the ball or the big toe, that they cannot really feel. It may have been there for a while, perhaps with some staining on the sock, before they spotted it. There is no pain, which is exactly why it is dangerous — the warning system that would normally make someone stop and rest the foot is not working. On looking, the skin may be broken with hard skin around it, and the foot may feel numb. This quiet, painless sore is the classic diabetic foot ulcer, and it deserves urgent attention even when it seems small.

Why diabetic feet are vulnerable

Two long-term effects of diabetes combine to put feet at risk. First, nerve damage (neuropathy) reduces feeling, so cuts, blisters and pressure sores are not felt and go unnoticed. Nerve damage can also change the foot's shape, creating high-pressure spots where ulcers form. Second, poor circulation from narrowed blood vessels means wounds get less oxygen and healing slows. On top of this, high blood sugar weakens the body's defence against infection. Together these mean a minor injury — a tight shoe, a stone, a small burn from a hot water bottle — can become an ulcer, and an ulcer can become a deep infection quickly and silently.

Assessing the ulcer

Clinicians look at several things. How big and how deep is the ulcer, and can they see or feel bone at the base? Are there signs of infection — spreading redness, warmth, swelling, discharge, a bad smell, or the person feeling generally unwell? Is the circulation good, checked by feeling for foot pulses and sometimes measuring blood flow? Is there feeling in the foot, tested with a fine thread or tuning fork? They also look for a hot, red, swollen foot without an obvious wound, which can be a serious condition called Charcot foot. Each finding shapes how urgently the person needs specialist care and whether infection needs treating.

Why it matters

Diabetic foot ulcers are a leading reason people with diabetes end up in hospital, and they carry a real risk of amputation if neglected. Infection can spread into the deeper tissues and bone, and poor circulation makes it hard for the body to fight back. The good news is that most of this harm is preventable. Ulcers found early, protected from pressure, kept clean and treated promptly can heal. The key is not to wait: because these ulcers often do not hurt, people can carry on walking on them, which drives the damage deeper. Fast referral to a specialist foot service changes outcomes dramatically.

The UK pathway and prevention

In the UK, people with diabetes should have their feet checked at least once a year to grade their risk. Anyone with a new foot ulcer, signs of infection, or a hot swollen foot should be referred urgently — usually within one working day — to the multidisciplinary foot care team, which brings together specialists to treat the wound, control infection, improve circulation and take pressure off the foot. Prevention is central: checking feet daily, wearing well-fitting shoes, never walking barefoot, avoiding hot water bottles, keeping blood sugar controlled, not smoking, and seeing a podiatrist. A small change spotted early can prevent an ulcer altogether.