Diabetic Foot Disease

Diabetic foot disease involves three elements: peripheral neuropathy (distal symmetrical polyneuropathy), peripheral vascular disease and infection. Neuropathy is usually the principal factor in diabetic foot disease, causing a loss of sensation and disruption of the normal pattern of nerves supplying the muscles of the foot. As a consequence, local areas of high pressure develop due to subtle changes in the internal anatomy of the foot, increasing the risk of the formation of calluses, especially on the 'pad' below the big toe. The neuropathic foot remains warm and the skin is of normal colour (as the blood supply is intact), although it tends to be dry. The foot is highly susceptible to mechanical damage due to loss of sensation, for example from objects that are trodden on and not noticed, or from grit in a shoe, or from inadvertent scalding or burning. Other clinical signs include diminished reflexes and although pain is often absent, this is not invariably the case. If present, the foot is often especially painful at night. People with neuropathic diabetic foot disease are at risk of ulceration on the sole of the foot and, more rarely, charcot arthropathy.

Peripheral vascular disease relates to disease and damage of the blood vessels supplying outlying areas of the body, in this case, the feet. About half of people with diabetic foot problems have peripheral vascular damage as a contributory cause and may be said to have neuro-ischaemic foot disease. The clinical signs and symptoms of this are somewhat different to those of purely neuropathic foot disease. Sensation in the foot is retained to a greater extent but it tends to feel cold and look pale due to the poor blood supply. Reflexes are retained but pulses are absent, again reflecting the poor blood supply. Calluses are less likely to form but there is a risk of ulcers developing on the extremities of the foot and in extreme cases, gangrene.

Ulcers are one manifestation of the third contributory cause of diabetic foot disease, which is infection. People with neuropathic or neuro-ischaemic foot disease are especially at risk of infection in their feet. In practice, the two types of foot disease are treated and managed in similar ways. However, peripheral vascular disease can occur in the absence of diabetes and known risk factors for its occurrence are smoking, hypertension and elevated levels of blood cholesterol. All these are of particular significance in diabetes and risks can be reduced by adopting a healthy lifestyle and diet and taking regular exercise.

Overall, ulceration and infection of the feet are the most common reason for hospital admittance in people with diabetes. Unfortunately, people with diabetes are 10 to 15 times more likely to undergo amputation (of one or more toes or, rarely, the whole foot), than the non-diabetic population. However, it must be emphasized that amputation is only ever carried out in extreme circumstances, when other treatments have failed and where there is a risk of non-healing and the spread of infection. Amputation may be needed, for example, if serious lesions or osteomyelitis (infection in the bone) occur repeatedly at the same site and do not heal or respond to antibiotic treatment, or if gangrene has set in.

General advice on foot care for diabetes patient

See more diabetic complications information.