How does diabetes affect your feet?

You might have heard of the phrase “diabetic foot” – but what does it actually mean? Why does diabetes affect the feet in particular? We spoke to Consultant Vascular Surgeon Mr S Tawqeer Rashid, a specialist in diabetic foot disease:

What is the diabetic foot?

A diabetic foot is a foot that shows problems usually due to type 2 diabetes, otherwise known as diabetes mellitus, but it can also occur due to type 1 diabetes. These problems include skin damage, ulceration, and infection.

Research estimates that someone with diabetes has a 15% risk of getting diabetic foot disease in their lifetime – though it may become as high as 25%.

How does a diabetic foot happen?

There are three main ways that diabetes can cause problems in your feet.

Firstly, over time the nerves in the foot get damaged, especially if you have poor control over your blood sugar levels. This is known as neuropathy. Neuropathy reduces the sensation in diabetic feet and the ability to feel pain, meaning that minor and especially repetitive injuries can cause loss of skin on the foot which is known as an ulcer - which may remain undiscovered for a long while.

Secondly, diabetic patients can also have a reduction in the blood supply to their feet known as ischaemia or peripheral arterial disease. If there is a poor blood supply to the foot, then the body also can’t support its own natural healing pathways – just think of not having enough fuel to operate a machine. This is the case in around half of diabetic foot ulcer patients.

Finally, diabetes can cause changes to the shape and structure of their feet (osteoarthropathy). If your foot shape has changed then certain parts may become more prominent, taking more of the weight than they should when you walk or rest your feet. Repetitive pressure damage to one area of skin on the foot may results in loss of that skin and formation of an ulcer.

Diabetic foot can also affect the toes. They can lose protective feeling (sensation), change shape, develop ulcers and become infected.

Is the diabetic foot painful?

Sometimes the damaged nerves in your foot can cause pain. This is called neuropathic pain and you’ll need a special type of pain killer to treat this.

However, most of the time the diabetic foot is not painful – and this is the problem. Normally, too much pressure over a long period of time on one area of your skin causes pain, so you move to re-distribute your weight away from that area. If you actually have skin damage or an ulcer that would normally be so painful that you would be unable to put any more pressure on it. Just think how painful a cut is! This is one time when it is good to feel pain – to prevent you damaging your body further.

Unfortunately, when diabetic patients have lost this “gift of pain” they can continue to damage the ulcerated area without realising they are doing this. As a result the ulcer can’t heal naturally.

What happens if the ulcer doesn’t heal?

If the ulcer doesn’t heal, it can become infected. When there is an infection - especially if it is trapped inside the foot and forms an abscess - the foot can be very painful. This situation is an emergency requiring immediate assessment in hospital and possibly surgery.

Unfortunately, diabetic patients are less able than other patients to fight off infection, meaning a diabetic foot is at a much higher risk of amputation - where either part of the foot or sometimes the leg needs to be removed. If the infection occurs in the toes, these can become gangrenous when they become black and die off. This also results in amputation – either naturally by the body (auto-amputation) or performed by a surgeon.

In general, 50% of diabetic foot ulcers go onto to get infected – and of these 20% end up with an amputation. Half of these amputations are “minor” where part of the foot is removed but half of these amputations are “major” where part of the leg is removed.

Therefore just over 5% of diabetic foot ulcers result in the loss of a leg.

How to avoid a diabetic foot ulcer and an amputation?

Firstly, good control of your diabetes is imperative. Studies have clearly shown that lower levels of glucose (sugar) in your blood reduces the chances of developing neuropathy and other complications of diabetes.

Secondly, regular and thorough checks of your feet will detect any early signs of damage. This is especially true if you have neuropathy. You should do this regularly yourself and at least annually through your GP who may feel you need to be under the care of a foot specialist called a podiatrist. They may even recommend specialist footwear. Diabetes UK have some good information on this.

Thirdly any other risk factors need to be well-controlled especially if you have peripheral arterial disease, including:

• high blood pressure
• high cholesterol
• avoidance of smoking
• a healthy diet and regular exercise.

Finally and most importantly if you develop an ulcer you must report to your podiatrist, GP or diabetic centre as soon as possible. Early treatment before the ulcer gets larger or infected is imperative and management of these ulcers are usually in specialist high-risk foot clinics with team of dedicated specialists working together in multi-disciplinary teams.