Nerve Damage - Long Term Complications: Diabetes

Content provided by the Faculty of the Harvard Medical School

Nerve damage

Nerve damage, or neuropathy, from diabetes has widespread effects, and again, the blame rests with abnormally high blood sugar levels. When nerve damage occurs, the network of nerves that relays messages to and from different parts of the body slows down, sends the wrong cues, or fails to work. Scientists aren't certain why this happens, but they think the damage may result when glucose attaches to or affects proteins in nerve cells, causing a chemical imbalance inside the nerves or restricting the blood flow to the nerves.

Nerve damage can cause changes in sensory perception, pain, or problems with digestive, bladder, bowel, or sexual function. About 60%–70% of people with diabetes have some signs of neuropathy that may be detectable only with a physical exam or special testing, and a smaller percentage has more severe symptoms. Serious neuropathy, especially when combined with vascular complications, can lead to foot ulcers and the loss of lower limbs.

Peripheral neuropathy

The most common type of nerve damage, known as peripheral neuropathy, affects the long nerves that extend from your spine to your arms and legs. Symptoms include numbness, tingling, and reduced sensitivity to light touch. Although more rare, a burning, shooting, or stabbing pain may also occur.

The real danger of this condition is that it lessens your sensitivity to vibration, touch, and pain, especially in your feet. This puts you at greater risk of injuring your feet due to poorly fitting shoes, high-impact exercise, or even walking. Peripheral neuropathy can make many daily activities difficult and can impair your ability to drive a car. It's essential to check your feet daily because a blister or even a puncture wound from a nail can be easily missed. If these problems go unnoticed, infections and decreased blood flow can complicate the situation, leading to sores or ulcers that sometimes become severe enough to warrant amputation (see "Damage to the feet and legs").

Focal neuropathy

A less common type of damage, focal neuropathy, targets a specific nerve or set of nerves, causing a weakness in facial, leg, arm, or eye muscles. Experts suspect that the nerves malfunction because an obstruction in a small blood vessel blocks their blood supply. The condition can appear as hand weakness, an inability to lift your leg, or double vision. The problem typically disappears over two to six months. Carpal tunnel syndrome, a nerve disorder of the hand and wrist, is especially common because the nerves appear to be more sensitive to compression from repeated motion.

Autonomic neuropathy

This nerve damage involves the autonomic nervous system, the nerves controlling automatic body functions such as digestion, sweating, and erections. Autonomic neuropathy produces a variety of unpleasant effects, such as racing heartbeat, profuse sweating, bloating, dizziness or nausea, vomiting, diarrhea, and constipation. People with this condition may not be able to empty their bladders completely (which can predispose them to bladder infections), and as many as half of diabetic men may develop erectile dysfunction (impotence). This is especially true for men who've had diabetes for many years.

Diagnosing nerve damage

Your doctor can usually diagnose diabetic neuropathy at an office visit. During the exam, he or she will test your reflexes and sensory perception. Although tests to confirm the diagnosis aren't usually necessary, some doctors perform nerve conduction tests to see if individual arm or leg nerves are affected. Other specialized tests can be used to diagnose slow stomach emptying, bladder sluggishness, or erectile dysfunction.

Treatment

Neuropathy, like retinopathy, can be prevented with tight glucose control. Gaining better control over your blood glucose can also ease discomfort. Your doctor may prescribe oral medications or topical creams to reduce pain and ensure a good night's rest. Occasionally, painkillers may be necessary as well.

Bowel disturbances. Eating more fiber may correct bowel disturbances. If your stomach empties too slowly, your doctor may recommend a medication such as metoclopramide (Reglan). If you're bothered by diarrhea, taking an antidiarrheal drug such as loperamide (Imodium) may help.

Erectile dysfunction. For men who suffer erectile dysfunction due to diabetes, about half can be helped by drugs that are phosphodiesterase inhibitors such as sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra); the use of vacuum devices before intercourse; or surgical implants.

Bladder problems. One way to prevent or handle bladder problems or incontinence is by training yourself to go to the bathroom every hour or two rather than waiting until you feel the urge. If this isn't helpful, your doctor may recommend oral drugs or surgery.

Dizziness. Dizziness or lightheadedness may also require some simple lifestyle changes. If standing up quickly brings on lightheadedness, try taking more time to change positions. Cutting out alcohol and increasing your dietary salt intake may also help.

The many forms of nerve damage are not easy to treat. The best way to avoid them is by keeping your blood glucose levels as close to normal as possible.

Last updated:	January 23, 2007