Diabetic Neuropathy: The Nerve Damage Of Diabetes
Diabetic neuropathies are a family of nerve disorders caused by diabetes. People with diabetes can, over time, have damage to nerves throughout the body. Neuropathies lead to numbness and sometimes pain and weakness in the hands, arms, feet, and legs. Problems may also occur in every organ system, including the digestive tract, heart, and sex organs. People with diabetes can develop nerve problems at any time, but the longer a person has diabetes, the greater the risk.
An estimated 50 percent of those with diabetes have some form of neuropathy, but not all with neuropathy have symptoms. The highest rates of neuropathy are among people who have had the disease for at least 25 years.
Diabetic neuropathy also appears to be more common in people who have had problems controlling their blood glucose levels, in those with high levels of blood fat and blood pressure, in overweight people, and in people over the age of 40. The most common type is peripheral neuropathy, also called distal symmetric neuropathy, which affects the arms and legs.
The causes are probably different for different varieties of diabetic neuropathy. Researchers are studying the effect of glucose on nerves to find out exactly how prolonged exposure to high glucose causes neuropathy. Nerve damage is likely due to a combination of factors:
Symptoms depend on the type of neuropathy and which nerves are affected. Some people have no symptoms at all. For others, numbness, tingling, or pain in the feet is often the first sign. A person can 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 involve the sensory or motor nervous system, as well as the involuntary (autonomic) nervous system. In some people, mainly those with focal neuropathy, the onset of pain may be sudden and severe.
Symptoms may include
In addition, the following symptoms are not due to neuropathy but nevertheless often accompany it:
Types Of Diabetic Neuropathy
Diabetic neuropathies can be classified as peripheral, autonomic, proximal, and focal. Each affects different parts of the body in different ways.
Neuropathy Affects Nerves Throughout The Body
|Peripheral neuropathy affects the nerves in your arms, hands, legs, and feet.|
This type of neuropathy damages nerves in the arms and legs. The feet and legs are likely to be affected before the hands and arms. Many people with diabetes have signs of neuropathy upon examination but have no symptoms at all. Symptoms of peripheral neuropathy may include
These symptoms are often worse at night.
Peripheral neuropathy may also cause muscle weakness and loss of reflexes, especially at the ankle, leading to changes in gait (walking). Foot deformities, such as hammertoes and the collapse of the midfoot, may occur. Blisters and sores may appear on numb areas of the foot because pressure or injury goes unnoticed. If foot injuries are not treated promptly, the infection may spread to the bone, and the foot may then have to be amputated. Some experts estimate that half of all such amputations are preventable if minor problems are caught and treated in time.
|Autonomic neuropathy affects the nerves in your lungs, heart, stomach, intestines, bladder, and sex organs.|
Autonomic neuropathy affects the nerves that control the heart, regulate blood pressure, and control blood glucose levels. It also affects other internal organs, causing problems with digestion, respiratory function, urination, sexual response, and vision. In addition, the system that restores blood glucose levels to normal after a hypoglycemic episode may be affected, resulting in loss of the warning signs of hypoglycemia such as sweating and palpitations.
Unawareness of Hypoglycemia
Normally, symptoms such as shakiness occur as blood glucose levels drop below 70 mg/dL. In people with autonomic neuropathy, symptoms may not occur, making hypoglycemia difficult to recognize.
However, other problems can also cause hypoglycemia unawareness so this does not always indicate nerve damage.
Heart and Circulatory System
The heart and circulatory system are part of the cardiovascular system, which controls blood circulation. Damage to nerves in the cardiovascular system interferes with the body's ability to adjust blood pressure and heart rate. As a result, blood pressure may drop sharply after sitting or standing, causing a person to feel light-headedor even to faint. Damage to the nerves that control heart rate can mean that it stays high, instead of rising and falling in response to normal body functions and exercise.
Nerve damage to the digestive system most commonly causes constipation. Damage can also cause the stomach to empty too slowly, a condition called gastroparesis. Severe gastroparesis can lead to persistent nausea and vomiting, bloating, and loss of appetite. Gastroparesis can make blood glucose levels fluctuate widely as well, due to abnormal food digestion.
Nerve damage to the esophagus may make swallowing difficult, while nerve damage to the bowels can cause constipation alternating with frequent, uncontrolled diarrhea, especially at night. Problems with the digestive system may lead to weight loss.
Urinary Tract and Sex Organs
Autonomic neuropathy most often affects the organs that control urination and sexual function. Nerve damage can prevent the bladder from emptying completely, allowing bacteria to grow in the bladder and kidneys and causing urinary tract infections. When the nerves of the bladder are damaged, urinary incontinence may result because a person may not be able to sense when the bladder is full or control the muscles that release urine.
Neuropathy can also gradually decrease sexual response in men and women, although the sex drive is unchanged. A man may be unable to have erections or may reach sexual climax without ejaculating normally. A woman may have difficulty with lubrication, arousal, or orgasm.
Autonomic neuropathy can affect the nerves that control sweating. When nerve damage prevents the sweat glands from working properly, the body cannot regulate its temperature properly. Nerve damage can also cause profuse sweating at night or while eating.
Finally, autonomic neuropathy can affect the pupils of the eyes, making them less responsive to changes in light. As a result, a person may not be able to see well when the light is turned on in a dark room or may have trouble driving at night.
Proximal neuropathy, sometimes called lumbosacral plexus neuropathy, femoral neuropathy, or diabetic amyotrophy, starts with pain in either the thighs, hips, buttocks, or legs, usually on one side of the body. This type of neuropathy is more common in those with type 2 diabetes and in older people. It causes weakness in the legs, manifested by an inability to go from a sitting to a standing position without help. Treatment for weakness or pain is usually needed. The length of the recovery period varies, depending on the type of nerve damage.
Occasionally, diabetic neuropathy appears suddenly and affects specific nerves, most often in the head, torso, or leg. Focal neuropathy may cause
Focal neuropathy is painful and unpredictable and occurs most often in older people. However, it tends to improve by itself over weeks or months and does not cause long-term damage.
People with diabetes also tend to develop nerve compressions, also called entrapment syndromes. One of the most common is carpal tunnel syndrome, which causes numbness and tingling of the hand and sometimes muscle weakness or pain. Other nerves susceptible to entrapment may cause pain on the outside of the shin or the inside of the foot.
Preventing Diabetic Neuropathy
The best way to prevent neuropathy is to keep your blood glucose levels as close to the normal range as possible. Maintaining safe blood glucose levels protects nerves throughout your body.
For additional information on preventing diabetes complications, including neuropathy, see the Prevent Diabetes Problems series, available from the National Diabetes Information Clearinghouse at 1-800-860-8747.
Neuropathy is diagnosed on the basis of symptoms and a physical exam. During the exam, the doctor may check 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.
The first step is to bring 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. Importantly, good blood glucose control may also help prevent or delay the onset of further problems.
Additional treatment depends on the type of nerve problem and symptom, as described in the following sections.
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.
More than half of all lower limb amputations in the United States occur in people with diabetes86,000 amputations per year. Doctors estimate that nearly half of the amputations caused by neuropathy and poor circulation could have been prevented by careful foot care. Here are the steps to follow:
For additional information on foot care, contact the National Diabetes Information Clearinghouse at 1-800-860-8747. Materials are also available at http://ndep.nih.gov/materials/pubs/feet/feet.htm.
To relieve pain, burning, tingling, or numbness, the doctor may suggest aspirin, acetaminophen, or nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen. (People with renal disease should use NSAIDs only under a doctor's supervision.) A topical cream called capsaicin is another option. Tricyclic antidepressant medications such as amitriptyline, imipramine, and nortriptyline, or anticonvulsant medications such as carbamazepine or gabapentin may relieve pain in some people. Codeine may be prescribed for a short time to relieve severe pain. Also, mexiletine, used to regulate heartbeat, has been effective in treating pain in several clinical trials.
Other pain treatments include transcutaneous electronic nerve stimulation (TENS), which uses small amounts of electricity to block pain signals, as well as hypnosis, relaxation training, biofeedback, and acupuncture. Walking regularly or using elastic stockings may also help leg pain.
To relieve mild symptoms of gastroparesis indigestion, belching, nausea, or vomitingdoctors suggest eating small, frequent meals, avoiding fats, and eating less fiber. When symptoms are severe, the doctor may prescribe erythromycin to speed digestion, metoclopramide to speed digestion and help relieve nausea, or other drugs to help regulate digestion or reduce stomach acid secretion.
To relieve diarrhea or other bowel problems, the doctor may prescribe an antibiotic such as tetracycline, or other medications as appropriate.
Dizziness and Weakness
Sitting or standing slowly may help prevent the light-headedness, dizziness, or fainting associated with blood pressure and circulation problems. Raising the head of the bed or wearing elastic stockings may also help. Some people may benefit from increased salt in the diet and treatment with salt-retaining hormones. Others may benefit from high blood pressure medications. Physical therapy can help when muscle weakness or loss of coordination is a problem.
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 gynecologist.
Points To Remember
Hope Through Research
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and the National Institute of Neurological Disorders and Stroke (NINDS) conduct and support research to help people with diabetes, including studies related to diabetic neuropathy. A complete listing of clinical research studies can be found at http://ClinicalTrials.gov.
For More Information
For more information, contact the following organizations:
American Diabetes Association
National Service Center
1701 North Beauregard Street
Alexandria, VA 22311
Phone: 1-800-232-3472 or 1-800-DIABETES (1-800-342-2383) Fax: (703) 549-6995
American Podiatric Medical Association
9312 Old Georgetown Road
Bethesda, MD 20814-1698
(1-800-366-8227) or (301) 571-9200
Fax: (301) 530-2752
Centers for Disease Control and Prevention
National Center for Chronic Disease
Prevention and Health Promotion
Division of Diabetes Translation
Mail Stop K-10
4770 Buford Highway, NE.
Atlanta, GA 30341-3717
Fax: (301) 562-1050
Juvenile Diabetes Research Foundation International
120 Wall Street, 19th floor
New York, NY 10005
Phone: 1-800-533-2873 or (212) 785-9500
Fax: (212) 785-9595
Lower Extremity Amputation Prevention Program
4350 East-West Highway, 9th floor
Bethesda, MD 20814
National Diabetes Education Program
1 Diabetes Way
Bethesda, MD 20892-3600
National Digestive Diseases Information Clearinghouse
2 Information Way
Bethesda, MD 20892-3570
Phone: 1-800-891-5389 or (301) 654-3810
Fax: (301) 907-8906
National Heart, Lung, and Blood Institute Information Center
P.O. Box 30105
Bethesda, MD 20824-0105
Phone: (301) 592-8573
Fax: (301) 592-8563
National Institute of Neurological Disorders and Stroke
P.O. Box 5801
Bethesda, MD 20824
National Kidney and Urologic Diseases Information Clearinghouse
3 Information Way
Bethesda, MD 20892-3580
Phone: 1-800-891-5390 or (301) 654-4415
Fax: (301) 907-8906
Pedorthic Footwear Association
7150 Columbia Gateway Drive, Suite G
Columbia, MD 21046-1151
Phone: 1-800-673-8447 or (410) 381-7278
Fax: (410) 381-1167
National Diabetes Information Clearinghouse
1 Information Way
Bethesda, MD 20892-3560
The National Diabetes Information Clearinghouse (NDIC) is a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The NIDDK is part of the National Institutes of Health under the U.S. Department of Health and Human Services. Established in 1978, the clearinghouse provides information about diabetes to people with diabetes and to their families, health care professionals, and the public. NDIC answers inquiries, develops and distributes publications, and works closely with professional and patient organizations and Government agencies to coordinate resources about diabetes.
Publications produced by the clearinghouse are carefully reviewed by both NIDDK scientists and outside experts. This fact sheet was reviewed by Peter J. Dyck, M.D., Peripheral Neuropathy Research Center, Mayo Clinic Rochester, Rochester, MN; Eva L. Feldman, M.D., Ph.D., Department of Neurology, University of Michigan, Ann Arbor, MI; and Aaron I. Vinik, M.D., The Diabetes Research Institute, Eastern Virginia Medical School, Norfolk, VA.
This e-text is not copyrighted. The clearinghouse encourages users of this e-pub to duplicate and distribute as many copies as desired.
NIH Publication No. 02-3185
Current as of June 24, 2005