Damage to one or more of the peripheral nerves caused by diabetes mellitus
- More common over the age of 40
- Diabetes mellitus sometimes runs in families
- Poor control of diabetes mellitus and smoking are risk factors
- Gender is not a significant factor
In diabetic neuropathy, one or more of the peripheral nerves that branch from the brain and spinal cord to the rest of the body are damaged as a result of diabetes mellitus. Diabetic neuropathy is the most common cause of peripheral neuropathy. If diabetes is poorly controlled, it results in high levels of glucose in the blood that damage the peripheral nerves directly and the blood vessels that supply them (see Diabetic vascular disease). Good control of diabetes reduces this risk.
About 3 in 10 people with diabetes mellitus have damage to one or more peripheral nerves, but only 1 of these 3 people develops significant symptoms.
People with diabetes mellitus who smoke increase the risk of damaging the blood vessels that supply the nerves.
What are the symptoms?
The symptoms of diabetic neuropathy usually develop slowly over a number of years. Rarely, they develop rapidly over days or weeks. Symptoms vary depending on which nerves are involved, but the feet are frequently affected. Less commonly, diabetic neuropathy may affect the larger nerves, mainly in the thighs. Symptoms may include:
Pins and needles.
Sharp, stabbing pains, which may disrupt sleep.
Discomfort or pain when walking (like walking on pebbles).
If sensation is lost, a minor injury to the foot, such as rubbing by badly fitting shoes, may not be noticed. Slow healing due to poor blood supply may lead to infection. If left untreated, ulcers may develop (see Leg ulcer) and, in severe cases, gangrene occurs.
Eventually, diabetic neuropathy may also affect the autonomic nerves that regulate automatic body functions such as blood pressure control and digestion. Damage to these nerves causes symptoms such as dizziness when standing (see Hypotension), diarrhoea, and erectile dysfunction.
What might be done?
Careful control of diabetes reduces the risk of developing diabetic neuropathy. However, if you develop symptoms of nerve damage, you should consult your doctor. He or she will probably be able to diagnose the condition from your symptoms. However, nerve conduction tests may need to be carried out in hospital to confirm which nerves are affected and to assess the severity of the damage (see Nerve and muscle electrical tests).
The goal of treatment of diabetic neuropathy is to prevent further nerve damage and the development of complications. Your doctor will help you to monitor your blood sugar level carefully and advise you about good foot care (see Living with diabetes). For example, you should check your feet regularly for cuts or abrasions, particularly if you have been wearing new shoes. You should avoid wearing open-toed sandals or walking barefoot. If you smoke, you should try to give up.
What is the prognosis?
Good control of blood glucose levels in diabetes mellitus not only reduces the risk of developing diabetic neuropathy but may also halt further progression of the disease. However, in most cases, nerve damage is irreversible.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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