Diabetic neuropathy

What are the causes?

The causes are different for different varieties of diabetic neuropathy. Nerve damage is likely due to a combination of factors:

• metabolic factors, such as high blood glucose, long duration of diabetes, low levels of insulin, and abnormal blood fat levels
  
• neurovascular factors, leading to damage to the blood vessels that carry oxygen and nutrients to the nerves
  
• autoimmune factors that cause inflammation in nerves
  
• mechanical injury to nerves, such as carpal tunnel syndrome
  
• inherited traits that increase susceptibility to nerve disease
  
• lifestyle factors such as smoking or alcohol use

What are the symptoms?

Symptoms depend on the type of neuropathy and the nerves affected. Some people have no symptoms at all. For others, numbness, tingling, or pain in the feet is often the first sign. A person may experience both pain and numbness. Often, symptoms are minor at first, and since most nerve damage occurs over several years, mild cases may go unnoticed for a long time.

Symptoms may include:

• numbness, tingling, or pain in the toes, feet, legs, hands, arms, and fingers
  
• wasting of the muscles of the feet or hands
  
• indigestion, nausea, or vomiting
  
• diarrhoea or constipation
  
• dizziness or faintness due to a fall in blood pressure on standing
  
• problems with urination
  
• erectile dysfunction (impotence) or vaginal dryness
  
• weakness

What are the types of diabetes neuropathy?

Diabetic neuropathies may be classified as peripheral, autonomic, proximal, and focal. Each affects different parts of the body in different ways.

• Peripheral neuropathy causes either pain or loss of feeling in the toes, feet, legs, hands, and arms.
  
• Autonomic neuropathy causes changes in digestion, bowel and bladder function, sexual response, and perspiration. It may also affect the nerves that serve the heart and control blood pressure. Autonomic neuropathy may also cause hypoglycaemia (low blood sugar) unawareness, a condition in which people no longer experience the warning signs of hypoglycaemia.
  
• Proximal neuropathy causes pain in the thighs, hips, or buttocks and leads to weakness in the legs.
  
• Focal neuropathy results in the sudden weakness of one nerve, or a group of nerves, causing muscle weakness or pain. Any nerve in the body may be affected.

How is the diagnosis made?

Neuropathy is diagnosed on the basis of symptoms and a physical examination. During the examination, the doctor may check the blood pressure and heart rate, muscle strength, reflexes, and sensitivity to position, vibration, temperature, or a light touch. The doctor may also do other tests to help determine the type and extent of nerve damage.

What is the treatment?

The first step is to bring the blood glucose levels within the normal range to prevent further nerve damage. Blood glucose monitoring, meal planning, exercise, and oral drugs or insulin injections are needed to control blood glucose levels. Although symptoms may get worse when blood glucose is first brought under control, over time, maintaining lower blood glucose levels helps lessen neuropathic symptoms.

Foot care

People with neuropathy need to take special care of their feet. The nerves to the feet are the longest in the body and are the ones most often affected by neuropathy. Loss of sensation in the feet means that sores or injuries may not be noticed and may become ulcerated or infected. Circulation problems also increase the risk of foot ulcers.
Here are the steps to follow:

• Clean your feet daily, using warm and not hot water and a mild soap. Avoid soaking your feet. Dry them with a soft towel; dry carefully between your toes.
  
• Inspect your feet and toes every day for cuts, blisters, redness, swelling, calluses, or other problems.
  
• Moisturize your feet with lotion, but avoid getting it between your toes.
  
• After a bath or shower, file corns and calluses gently with a pumice stone.
  
• Each week or when needed, cut your toenails to the shape of your toes.
  
• Always wear shoes or slippers to protect your feet from injuries. Prevent skin irritation by wearing thick, soft, seamless socks.
  
• Wear shoes that fit well and allow your toes to move.
  
• Before putting your shoes on, look them over carefully and feel the insides with your hand to make sure they have no tears, sharp edges, or objects in them that might injure your feet.

Pain relief

To relieve pain, burning, tingling, or numbness, the doctor may suggest aspirin, acetaminophen, or nonsteroidal anti-inflammatory drugs (NSAIDs). Topical creams and antidepressant medications or anticonvulsant medications may relieve pain in some people.

Gastrointestinal problems

To relieve mild symptoms of gastroparesis, indigestion, belching, nausea, or vomiting, doctors suggest eating small, frequent meals, avoiding fats, and eating less fibre. When symptoms are severe, the doctor may prescribe medication to speed digestion and help relieve nausea.

Dizziness and weakness

Sitting or standing slowly may help prevent dizziness or fainting associated with blood pressure and circulation problems. Some people may benefit from increased salt in the diet and treatment with salt-retaining hormones.

Urinary and sexual problems

To clear up a urinary tract infection, the doctor will probably prescribe an antibiotic. Drinking plenty of fluids will help prevent another infection. People who have incontinence should try to urinate at regular intervals (every 3 hours, for example) since they may not be able to tell when their bladder is full.

To treat erectile dysfunction in men, the doctor will first do tests to rule out a hormonal cause. Several methods are available to treat erectile dysfunction caused by neuropathy, including taking oral drugs, using a mechanical vacuum device, or injecting a drug called a vasodilator into the penis before sex. The vacuum and vasodilator raise blood flow to the penis, making it easier to have and maintain an erection. Another option is to surgically implant an inflatable or semirigid device in the penis. A constriction ring or penile sling may be helpful.

Vaginal lubricants may be useful for women when neuropathy causes vaginal dryness. To treat problems with arousal and orgasm, the doctor may refer the woman to a gynaecologist.

What is the prevention?

The best way to prevent neuropathy is to keep the blood glucose levels as close to the normal range as possible. Maintaining safe blood glucose levels protects nerves throughout the body.