Diabetic neuropathy: the nerve damage of diabetes – Pamphlet
What is diabetic neuropathy?
Diabetic neuropathy is a nerve disorder causEd by diabetes. People who have had diabetes for years may experience numbness and sometimes pain in their hands, feet, and legs. Nerve damage caused by diabetes can also lead to problems with indigestion, diarrhea or constipation, dizziness, bladder infections, and impotence. In some cases, damaged nerves can strike suddenly, causing pain, weakness, and weight loss. Depression may follow. While some treatments are available, a great deal of research still needs to be done to understand how diabetes affects the nerves and to find better treatments for this complication.
How common is diabetic neuropathy?
Nerve problems can affect anybody with diabetes, but they are most common in people who have had diabetes more than 10 years. The majority of patients with neurological impairment due to diabetes do not have symptoms such as pain or numbness. However, some recent studies have reported that:
* 10 years after diagnosis, 30 percent of diabetes patients have symptoms or signs of diabetic neuropathy;
* 25 years after diagnosis, 40 percent of diabetes patients have symptoms or signs of neuropathy;
* 50 years after diagnosis, half of all diabetes patients have symptoms or signs of neuropathy.
Diabetic neuropathy appears to be more common in smokers, people over 40 years of age, and those who have had problems controlling the levels of glucose in their blood.
What causes diabetic neuropathy?
Scientists do not know how diabetic neuropathy occurs, but it is likely that several factors come into play. High blood glucose causes chemical changes in nerves, impairing their ability to transmit nerve signals. High blood glucose also damages blood vessels that carry oxygen and nutrients to the nerves. Also, inherited factors probably unrelated to diabetes may make some people more susceptible to nerve disease than others.
The study of the chemical changes that happen to nerves exposed to high blood glucose is a very active area of research. A normal substance called aldose reductase converts glucose to a type of sugar alcohol called sorbitol. Scientists have found that when tissues have a high level of glucose, sorbitol builds up and apparently damages the membranes lining body tissues.
Scientists have noted that in animals and humans with diabetes, nerves have less than normal amounts of a substance called myoinositol. It is thought that myoinositol plays a role in how nerve cells use energy to maintain the correct balance of salts. This balance is important to cells’ ability to conduct nerve impulses.
Studies have also shown that proteins age more quickly when exposed to high glucose. This has the effect of weakening certain connective proteins called collagens, which line and support nerve tissue. While these changes occur with normal aging, high blood glucose speeds up the damage.
It is likely that all three processes are chemically linked. Scientists are studying how these changes occur, how they are connected, how they cause nerve damage, and how the damage can be prevented and treated.
What are the symptoms of diabetic neuropathy?
The symptoms of diabetic neuropathy vary a great deal. Some people notice no symptoms, while others are disabled by severe problems. Neuropathy may cause both pain and insensitivity to pain in the same person. Often, symptoms are slight at first, and since most nerve damage occurs over years, mild cases may go unnoticed for a long time. In some people, though, mainly those afflicted by mononeuropathy (see page 4), the onset of pain may be sudden and severe.
Doctors divide diabetic neuropathy into three main types:
(also called “somatic neuropathy” or “distal sensory polyneuropathy”) The most common type of neuropathy, peripheral neuropathy can affect any of the nerves that transmit sensation throughout the body. However, the nerves of the limbs, and especially the feet, seem affected most often. Peripheneuropathy usually involves nerves on both sides of the body. Some of the most common symptoms of this kind of neuropathy are:
* numbness or insensitivity to pain or temperature;
* tingling, burning, or prickling;
* sharp pains or cramps; and
* extreme sensitivity to touch, even very light touch.
These symptoms are often worse at night.
After years of peripheral neuropathy, the damage to nerves may result in loss of reflexes and muscle weakness. These, in turn, may cause:
* loss of balance and coordination;
* inability to raise the foot;
* curling of the toes or other foot problems.
Often the foot becomes wider and shorter, the gait changes, and foot ulcers appear as pressure is put on parts of the foot that are less protected.
Loss of sensation may occur without the warning signs of pain, numbness or tingling. As the damaged nerve grows less sensitive to pain, it is easy to overlook foot problems when they first happen. Injuries can easily become infected because the poor circulation caused by diabetes impedes healing. If an injury is not treated in time, the infection may lead to gangrene, sometimes requiring amputation of the limb. However, problems caused by minor injuries can usually be controlled if they are caught in time.
(also called “visceral neuropathy”) Autonomic neuropathy is usually found in people who already have peripheral neuropathy. Autonomic neuropathy affects the nerves that serve the heart and internal organs and produces changes in:
Urination and Sexual Response
Autonomic neuropathy most often affects the organs that control urination and reproduction. Nerve damage prevents the bladder from emptying completely, so bacteria grow more easily in the urinary tract (bladder or kidneys). When the nerves of the bladder are damaged, it may be difficult to control the bladder or to know when it is full.
The nerve damage and circulatory problems of diabetes can also lead to frequent vaginal infections and a gradual loss of sexual sensation or response in both men and women, although sex drive is unchanged. A man may be unable to have erections or may reach sexual climax without ejaculating normally.
Autonomic neuropathy can also affect how food is digested. Nerve damage can cause the stomach to empty too slowly, a disorder called gastric stasis. When the condition is severe (gastroparesis), a person can have persistent nausea and vomiting, bloating, and loss of appetite. Blood glucose levels tend to fluctuate wildly.
If nerves in the esophagus are involved, swallowing may be difficult. Nerve damage, to the bowels can cause constipation or frequent diarrhea, especially at night. Problems with the digestive system often lead to weight loss.
Autonomic neuropathy least often affects the cardiovascular system, which controls the circulation of blood throughout the body. When it occurs, the nerve impulses from various parts of the body which signal the need for blood are not transmitted normally. As a result, blood pressure may drop sharply after sitting or standing, causing a person to feel dizzy or lightheaded, or even to faint (orthostatic hypotension).
Neuropathy that affects the cardiovascular system may also cause painless heart attacks and may raise the risk of a heart attack during general anesthesia. It can also hinder the body’s normal response to low blood sugar or hypoglycemia.
Sweating and Salivation
Autonomic neuropathy can affect the nerves that control sweating and salivation. Sometimes, nerve damage interferes with the activity of the sweat glands, making it difficult to tolerate heat. Other times, it causes profuse sweating at night or while eating (gustatory sweating).
(including “multiplex neuropathy”) Occasionally, diabetic neuropathy appears suddenly and affects specific nerves, most often in the torso, leg, or head. When mononeuropathy occurs, it may cause:
* pain in the front of the thigh;
* severe pain in the lower back or pelvis;
* Chest or abdominal pain sometimes mistaken for angina, heart attack, or appendicitis;
* aching behind the eye;
* inability to focus the eye;
* double vision;
* paralysis on one side of the face (Bell’s palsy); or problems with hearing.
This kind of neuropathy is unpredictable and occurs most often in older people who have mild diabetes. Although mononeuropathy can be very painful, it tends to improve by itself after a period of weeks or months without causing long-term damage.
How do doctors diagnose diabetic neuropathy?
A doctor diagnoses neuropathy from symptoms and a physical exam. During the exam, the doctor may check muscle strength, reflexes, and sensitivity to position, vibration, temperature, and light touch. Sometimes special tests are used to help pinpoint the cause of symptoms and suggest treatment:
* Ultrasound employs sound waves too high to hear, which produce an image showing how well the bladder and other parts of the urinary tract are functioning.
* Nerve conduction studies check the flow of electrical current through a nerve. With this test, an image of the nerve impulse is projected on a screen as it transmits an electrical impulse. Impulses that seem slower or weaker than usual indicate possible damage to the nerve. This test allows the doctor to assess the condition of all of the nerves in the limb.
* Electromyography (EMG) is used to see how well muscles respond to electrical impulses transmitted by the nerves nearby. With an EMG, the electrical activity of the muscle is displayed on screen. A response that is slower or weaker than usual suggests damage, to the muscle. This test is often done at the same time as nerve conduction studies.
* Nerve biopsy involves removing a sample of nerve tissue, which is examined for damage. This test is most often used in research settings.
If your doctor suspects autonomic neuropathy, you may also be referred to a specialist in digestive disorders (gastroenterologist) for additional tests.
How is diabetic neuropathy usually treated?
Treatment aims at relieving discomfort and preventing further tissue damage. The first step is to bring blood sugar under control by diet and oral drugs or insulin injections, if needed. Although symptoms can sometimes worsen as blood sugar is brought under control with intensive treatment, careful long-term monitoring of blood sugar helps reverse the pain or loss of sensation that neuropathy can cause. Good control of blood sugar with diet and, if necessary, drug therapy may also help prevent or delay the onset of further problems.
Another important part of treatment involves special care of the feet, which are especially prone to problems. (See section under foot care.)
A number of medications are used to relieve the symptoms of diabetic neuropathy:
* Pain, burning, tingling, or numbness
Your doctor may suggest an analgesic such as aspirin or acetaminophen; an anti-inflammatory drug containing ibuprofen; antidepressant medications such as amitriptyline, sometimes used with fluphenazine; or nerve medications such as carbamazepine or phenytoin sodium. Codeine is sometimes prescribed for short-term use to relieve severe pain.
Your doctor may also prescribe a therapy known as transcutaneous electronic nerve stimulation (TENS). In this treatment, small amounts of electricity block pain signals as they pass through a patient’s skin. Other treatments include hypnosis, relaxation training, biofeedback, and acupuncture. Some people find that walking regularly or using elastic stockings helps relieve leg pain. Warm (not hot) baths, massage, or an analgesic ointment such as Ben Gay may also help.
* Indigestion, belching, nausea or vomiting
For patients with mild symptoms of slow stomach emptying, doctors suggest eating small, frequent meals and avoiding fats. Eating less fiber may also relieve symptoms. For patients with severe gastroparesis, the doctor may prescribe metoclopramide, which speeds digestion and relieves nausea. Other drugs that help regulate digestion or reduce stomach acid secretion may also be used. In each case, the potential benefits of these drugs need to be weighed against their side effects.
* Diarrhea or other bowel problems
Antibiotics or clonidine HCl, a drug used to treat high blood pressure, are some times prescribed. A wheat-free diet may also help bring relief since the gluten in flour sometimes causes diarrhea.
* Urinary tract infections
Your doctor may prescribe an antibiotic to clear up an infection and suggest drinking more fluids to prevent further infections. It is also a good idea to urinate at regular times (every 3 hours, for example) since you may not be able to tell when your bladder is full.
* Lightheadedness, dizziness, or fainting
Sitting or standing very slowly may help prevent these problems. Raising the head of your bed and wearing elastic stockings may also help. Increased salt in the diet and treatment with salt-retaining hormones such as fludrocortisone are other possible approaches. In research studies, drugs used to treat hypertension have increased blood pressure in some patients.
* Muscle weakness or loss of coordination
Physical therapy can often help strengthen muscles and improve coordination.
The nerve and circulatory problems of diabetes can disrupt normal sexual function. After ruling out a hormonal cause of impotence, your doctor can advise you about the different methods available to treat impotence caused by neuropathy. Short-term solutions involve using a mechanical vacuum device or injecting a drug called a vasodilator into the penis before sex. Both methods raise blood flow to the penis, making it easier to have and maintain an erection. Surgical procedures, in which an inflatable or semi-rigid device is implanted in the penis, offer a more permanent solution. For some people, counseling may help relieve the stress caused by neuropathy and restore sexual function.
In women who feel their sexual life is not satisfactory, the role of diabetes and the solutions are less clear. Illness, vaginal or urinary infections, and anxiety about pregnancy complicated by diabetes can, for example, interfere with a woman’s ability to enjoy intimacy. Infections can be reduced by good blood glucose control. Counseling may also help a woman identify and cope with sexual concerns.
People with diabetes have to take special care of their feet. Since the nerves to the feet are the longest in the body, they are most often affected by neuropathy. At least 15 percent of all people with diabetes eventually have a foot ulcer, and 6 out of every 1,000 lose a limb to infection. However, doctors estimate that nearly three quarters of all amputations caused by neuropathy can be prevented with careful foot care.
Every day, you should check your feet and toes for any cuts, sores, bruises, bumps, or infections–using a mirror if necessary. Since diabetic neuropathy often causes numbness, you may be able to see injuries before you feel any discomfort. Also, poor circulation may cause infections to heal more slowly. To prevent foot problems from developing:
* Wash your feet daily, using warm water and a mild soap. (If you have neuropathy, you should test water temperature with your wrist.) Doctors do not advise soaking your feet for long periods since you may lose protective calluses. Dry your feet carefully with a soft towel, especially between toes.
* Cover your feet (except for the skin between the toes) with petroleum jelly, a lotion containing lanolin, or cold cream before putting on shoes and socks. The diabetic foot tends to sweat less than normal, leading to dry, cracked skin.
* Wear thick, soft socks, and avoid wearing slippery stockings, mended stockings, or stockings with seams.
* Wear shoes that fit your feet well and allow your toes to move. Break in new shoes gradually, wearing them for only an hour at a time. After years of neuropathy, as reflexes are lost, it is common for the feet to become wider and flatter. If you have problems finding shoes that fit well, ask your doctor to refer you to a specialist who can fit you with corrective shoes or inserts.
* Examine your shoes before putting them on to make sure they have no tears o sharp edges that might injure your feet.
* Cut your toenails straight across, but be careful not to leave any sharp corners that could cut the next toe.
* Use an emery board or a pumice stone to file away dead skin, but don’t remove calluses, which act as protective padding. Don’t try to cut off any growths yourself, and avoid using harsh chemicals such as wart remover on your feet.
* Don’t take very hot baths and never go barefoot, even on the beach or by a pool.
* Wear socks if feet are cold at night–no heating pads or hot water bottles.
* Avoid sitting with your legs crossed. This can reduce the flow of blood to the feet.
* Ask your doctor to check your feet at every visit, and call your doctor if you notice that a sore isn’t healing well.
* If you’re not able to take care of your own feet, ask your doctor to recommend a podiatrist (specialist in the care and treatment of feet) who can help.
Some General Hints
* If you smoke, try to stop since smoking makes circulatory problems worse and increases the risk of neuropathy and heart disease.
* Ask your doctor to suggest an exercise routine that’s right for you. Many people who exercise regularly find the pain of neuropathy is less severe. Aside from helping you reach and maintain your ideal weight, exercise also improves the body’s use of insulin, helps improve circulation, and strengthens muscles. Check with your doctor before starting exercise that can be hard on your feet, such as running or aerobics.
* Cut back on the amount of alcohol you drink. Recent research has indicated that as few as four drinks per week can worsen neuropathy.
Are there any experimental treatments for diabetic neuropathy?
Though still under study, new therapies may eventually prevent or reverse diabetic neuropathy. Extensive testing is required by the U.S. Food and Drug Administration to establish the safety and efficacy of drugs before they are approved for widespread use.
A new topical cream, capsaicin, is now in clinical trials and may prove to reduce the pain of neuropathy. Scientists believe that the ointment, a cayenne pepper extract, depletes the chemical that transmits pain signals to the brain.
Many doctors prescribe vitamin Bl because it appears to keep neuropathy from progressing, but there is no hard evidence of its benefits, and others feel it should not be prescribed. In addition, researchers are exploring treatment with another B vitamin called myoinositol. Early findings have shown that nerves in diabetic animals and humans have less than normal amounts of this substance. With supplements, myoinositol levels are increased in tissues of diabetic animals, but research is still needed to show any concrete, lasting benefits.
Another area of research concerns the drug aminoguanidine. In animals, aminoguanidine blocks cross-linking of proteins that occurs more quickly than normal in tissues exposed to high glucose. Very early clinical tests are under way to determine the effects of aminoguanidine in humans.
One approach that appeared promising involved the use of aldose reductase inhibitors. These are a class of drugs that block the formation of the sugar alcohol sorbitol, which is thought to damage nerves. Scientists hoped these drugs would prevent and might even repair nerve damage. But so far, clinical trials have shown these drugs to have major side effects while improving neuropathy in only a small number of patients.
The National Institutes of Health (NIH) is an agency of the Public Health Service under the U.S. Department of Health and Human Services. Its mission is to improve human health through biomedical research. Several components of NIH–the National Institute of Diabetes and Digestive and Kidney Diseases, the National Institute of Neurological Disorders and Stroke, and the National Institute of Dental Research–conduct and support research on the nerve complications of diabetes. The knowledge gained from this research may one day offer a way to prevent or cure diabetic neuropathy and bring relief to millions of people.
Resources on Diabetes
American Diabetes Association
National Service Center
1660 Duke Street
Alexandria, VA 22314
1-800-232-3472 or (703) 549-1500
A private, voluntary organization that fosters public awareness of diabetes and supports and promotes diabetes research. The American Diabetes Association has printed information on many aspects of diabetes, and local affiliates sponsor community programs. Local affiliates can be found in the telephone directory or through the national office.
American Dietetic Association
216 W. Jackson Boulevard
Chicago, IL 60606-6995
A professional organization that can help someone locate a nutritionist in the community.
American Heart Association
7320 Greenville Avenue
Dallas, TX 75231
A private, voluntary organization that has literature on heart disease and how to prevent it. Contact the local affiliate of the American Heart Association listed in telephone directories.
Juvenile Diabetes Foundation International
432 Park Avenue, South
New York, NY 10016
A private, voluntary organization with an interest in insulin-dependent diabetes. Local affiliates are located across the country.
National Diabetes Information Clearinghouse
9000 Rockville Pike
Bethesda, MD 20892
The National Diabetes Information Clearinghouse has a variety of publications for distribution to the public and to health professionals. The clearinghouse is a program of the National Institute of Diabetes and Digestive and Kidney Diseases, the lead federal agency in diabetes research.
For general information about diabetes:
Insulin-Dependent Diabetes, 1990,
A booklet prepared by the National Institute of Diabetes and Digestive and Kidney Diseases. Single copies are free from the National Diabetes Information Clearinghouse.
Noninsulin-Dependent Diabetes, 1987,
A booklet prepared by the National Institute of Diabetes and Digestive and Kidney Diseases. Single copies are free from the National Diabetes Information Clearing house.
Diabetes Dictionary, 1989, A booklet prepared by the National Institute of Diabetes and Digestive and Kidney Diseases.
Single copies are free from the National Diabetes Information Clearinghouse.
For more information about diabetic neuropathy and diabetes research:
Albert, Leonard, “Restraining Pail: What’s available for easing the pain of diabetic neuropathy,” Diabetes Forecast, January 1988, pp. 39-41.
Bell, David and Clements, Jr., Rex, “Diabetes and the Digestive System,” Diabetes Forecast, December 1987, pp. 43-46.
Cohen, Margo et al., Managing Diabetes Complications,” Patient Care, December 15, 1988, pp. 28-39.
Diabetes Mellitus: Trans-NIH Research, NIDDK 1991. Single copies are free from the National Diabetes Information Clearinghouse.
Dyck, Peter James, “Aldose Reductase Inhibitors and Diabetic Neuropathy,” Diabetes Forecast, May 1989, pp. 41-43.
Dyck, Peter James, “Resolvable Problems in Diabetic Neuropathy,” The Journal of NIH Research, June 1990, pp. 57-62.
Gerding, Dale et al., “Problems in Diabetic Foot Care,” Patient Care, August 15, 1988, pp. 102-118.
Haase, Gunter et al., “Neuropathy: Diabetic? Nutritional?,” Patient Care, May 15, 1990, pp. 112-134.
Jaspan, Jonathan et al., “GI Complications of Diabetes,” Patient Care, January 15, 1990, pp. 108-128.
“Report and Recommendations of the San Antonio Conference on Diabetic Neuropathy,” sponsored by the American Diabetes Association and the American Academy of Neurology, Diabetes Care, July/August 1988, pp. 592-597.
Vinik, Aaron and Mitchell, B. “Clinical Aspects of Diabetic Neuropathies,” Diabetes/Metabolism Reviews, May 1988, pp. 223-253.
This publication is not copyrighted. Readers are encouraged to duplicate and distribute as many copies as needed. Single copies may be obtained from the National Diabetes Information Clearinghouse, Box NDIC, 9000 Rockville Pike, Bethesda, MD 20892.
COPYRIGHT 1991 U.S. Department of Health and Human Services
COPYRIGHT 2004 Gale Group