How can diabetes affect your patients’ feet? Emma Howard, Specialist Podiatrist and Team Leader, Oxford Health NHS Foundation Trust – on behalf of the Diabetes Research & Wellness Foundation – investigates, overviews what neuropathy is, and presents tips as to how individuals can keep their feet healthy.
What is Neuropathy?
Diabetic foot complications develop as a result of raised blood glucose levels over time and are of two main types.
Ischaemia happens when small blood vessels in the feet become partially blocked, leading to reduced blood supply to the feet.
Diabetic neuropathy occurs in people with type 1 and type 2 diabetes and is the commonest cause of loss of feeling in the leg.
Damage to the nerves results from erosion of the protective sheath surrounding the nerves. This can result from raised blood glucose levels disrupting the structure and function of the nerve, or reduced flow in small blood vessels supplying nerves in the feet.
Neuropathy can affect nerves throughout the body, but due to the long length of the nerves to the foot, damage occurs there first.
Different Symptoms and Types of Neuropathy
Sensory Diabetic Neuropathy
This neuropathy affects the nerves which carry messages from the skin, bones and muscles to the brain and is the most common. The changes usually happen in both feet at the same time and can progress from your toes to your feet and sometimes the legs, fingers and hands can be affected, although this is less common.
Symptoms can range from feelings of numbness or walking on cotton wool or sponges, to more severe symptoms like pins and needles, tingling, burning or small electric shocks. Symptoms are typically worse at night.
Sensory neuropathy can affect balance, but the main problem is the inability to feel damage to your feet, and sense pain associated with this. You could tread on a sharp object, or even burn your feet in hot water without your feet detecting pain to tell you your foot is damaged. The lack of sensation can allow further damage to occur which may result in a foot ulcer.
Autonomic neuropathy affects the nerves which control involuntary activity in the body. Damaged nerves can lead to more blood flowing to the foot. This results in a reduction of sweating and moisture in the foot. The skin will be warm but very dry. Overtly dry skin can lead to deep cracks in the skin, especially around the heels, and could lead to a foot ulcer (see Figure 2).
Small muscles in the foot could lose strength and size due to the loss of nerve function. This means that the toes start to claw and the arch of the foot becomes higher. As the foot changes shape more pressure is loaded on the bones under the foot and calluses can form.
Reduced Blood Flow
Reduced blood flow (ischaemia) is caused by a process called atherosclerosis where small blood vessels within the foot develop thickened walls. Thickened walls means less blood flow to the foot. Ischaemia is exacerbated by raised blood glucose, high blood pressure, high cholesterol and smoking.
The absence of foot pulses will indicate that blood flow is reduced to the foot. Other symptoms which suggest ischaemia are cramp in the calves during exercise, which is relieved by rest, or pain in the feet when the feet are elevated. If your patient has neuropathy, symptoms are not always present, but signs such as cold feet or thin / discoloured skin may also indicate ischaemia.
Diagnosis and Treatment
Assessment of the feet for neuropathy should be carried out annually. This may be by a podiatrist or trained health professional. Tests include the use of a monofilament (a graded nylon filament applied to the foot), or using a tuning fork, which tests the perception of vibration.
Tests determine the presence of neuropathy and reduce the risk of foot ulcers developing.
Reduced blood supply to the foot should always be taken seriously.
Carefully managed exercise and stopping smoking are essential.
Medication for raised cholesterol and high blood pressure may also be appropriate.
Top Tips for Healthy Feet
Check Feet Daily
If your patient has poor sight, they should ask a family member or carer to help. They should look for colour change, swelling, damage to skin, heat, redness, discharge, and pain / discomfort.
Your patient should never try to treat corns or hard skin themselves (see Figure 3). A trained podiatrist will remove the callus or corn thereby reducing pressure on the area. If not treated the pressure may lead to ulceration. Never apply corn plasters or acid preparations. They can burn the skin and cause a wound. Neuropathy or ischaemia makes you especially susceptible.
If your patient can easily cut their toenails, do not let diabetes stop them. Trim them straight across and file rough edges. If they suspect a deformity, infection or ingrown nails, they should consult a podiatrist.
Your patient should always wear footwear for protection; feet are easily damaged when bare. They should check shoes and socks for foreign objects which cause skin damage and purchase well-fitting shoes.
Your patient should check the temperature of water and avoid hot water bottles. Heat sources can burn the skin if neuropathy is present and a wound can develop.
Your patient should wash their feet daily and dry well between the toes to avoid athlete’s foot. Skin can get very dry; they should apply moisturising cream daily, except between the toes.
Your patient should apply sun cream to prevent burning and protect their soles of their feet from heat by wearing sandals. They should take a small first aid kit to treat wounds and seek advice if they don’t heal (see Figure 4).
Diabetic foot complications can be prevented, but without care will progress with time. The following measures can be advised to your patients to help prevent complications:
• Control diabetes as effectively as possible
• Attend foot screening
• Seek treatment for foot problems, such as corns and hard skin
• Don’t trust the nerves in the foot if they are damaged; your patient should trust their sight and their instincts
When looking for a podiatrist, remember that they all should be registered with the Health Care Professions Council.
Patients can search for a local podiatrist at www.cop.org.uk/find-a-podiatrist or ask your diabetes healthcare professional.
*V6.0 published: October 2018
About the Diabetes Research & Wellness Foundation
Staying Well Until a Cure is Found
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