All About Diabetic
Neuropathy
& Nerve Damage Caused By Diabetes
What Is Diabetic Neuropathy?
Diabetic neuropathy is a nerve disorder caused by
diabetes. Common symptoms of neuropathy include numbness
and sometimes pain in the hands, feet, or legs.
Nerve damage caused by diabetes can also lead to
future problems with internal organs such as the digestive
tract, heart, and sexual organs causing indigestion,
diarrhea or constipation, dizziness, bladder infections,
and impotence. In some cases, neuropathy can flare
up suddenly, causing weakness and weight loss. Depression
may follow.
While some diabetes treatments are available, a great
deal of research is still needed to understand how
diabetes affects the nerves and to find more effective
treatments for this diabetic complication.
Can
Diabetic Neuropathy Be Prevented?
A 10-yr clinical study involving more than 1,400
volunteers with insulin-dependent diabetes was
recently completed by the National Institute of Diabetes
and Digestive and Kidney Diseases. The National Institute's
study verified keeping blood sugar levels as close
to the normal range as possible slows the onset and
progression of nerve disease caused by diabetes.
The Diabetes Control and Complications Trial studied
2 groups of volunteers: those who followed a standard
diabetes management routine and those who intensively
managed their diabetes.
Persons in the intensive diabetes management group took multiple
injections of insulin daily or used an insulin pump
and monitored their blood glucose at least four times
a day to try to lower their blood glucose levels to
the normal range.
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After 5-yrs tests of neurological function showed
the risk of nerve damage was reduced by 60 percent
in the intensively managed group. People in the standard
treatment group, whose average blood glucose levels
were higher, had higher rates of neuropathy.
Although the DCCT included only patients with IDDM,
researchers believe people with non-insulin-dependent
diabetes would also benefit from maintaining generally
lower levels of blood sugar/glucose.
What
Causes Diabetic Neuropathy?
Unfortunately, researchers and doctors do not really
know what causes neuropathy, but several factors are
likely to contribute to the disorder. High blood glucose,
a condition associated with diabetes, causes chemical
changes in nerves. These changes impair nerves abilities
to transmit signals. High blood glucose also damages
blood vessels that carry oxygen and nutrients to the
nerves. In addition, inherited factors probably unrelated
to diabetes may make some people more susceptible
to nerve disease than others.
How high blood glucose leads to nerve damage is a
subject of intense research. The precise mechanism
is not known. Researchers have discovered high glucose
levels affect many metabolic pathways in the nerves,
leading to an accumulation of a sugar called sorbitol
and depletion of a substance called myoinositol. However,
studies in humans have not shown convincingly these
changes are the mechanism that causes nerve damage.
More recently, researchers have focused on the effects
of excessive glucose metabolism on the amount of nitric
oxide in nerves. Nitric oxide dilates blood vessels.
In a person with diabetes, low levels of nitric oxide
may lead to constriction of blood vessels supplying
the nerve, contributing to nerve damage.
Another promising area of research centers on the
effect of high glucose attaching to proteins, altering
the structure and function of the proteins and affecting
vascular function. Researchers are studying how these
changes occur, how they are connected, how they cause
nerve damage, and how to prevent and treat damage.
People with diabetes can develop nerve problems at
any time. Significant clinical neuropathy can develop
within the first 10 years after diagnosis of diabetes
and the risk of developing neuropathy increases the
longer a person has diabetes. Some recent studies
have reported that 60 percent of patients with diabetes
have some form of neuropathy, but in most cases (30
to 40 percent) there are no symptoms. Approx' 30 to
40 percent of patients with diabetes have symptoms
suggesting neuropathy, compared with only 10 percent
of people without diabetes. Diabetic neuropathy appears
to be more common in smokers, people over age 40,
and those who have had problems controlling their
blood glucose levels.
What
Are Typical Symptoms Of Diabetic Neuropathy?
Symptoms of diabetic neuropathy vary. Numbness and
tingling in feet are often the first sign. Some people
notice no symptoms, while others are severely disabled.
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
a period of years, mild cases may go unnoticed for
a long time. In some people, mainly those afflicted
by focal neuropathy, the onset of pain may be sudden
and severe.
Diabetic
Neuropathy Can Affect Virtually Every Part Of The Body
Diffuse (Peripheral) Neuropathy
Diffuse (Autonomic) Neuropathy
- Heart
- Digestive System
- Sexual organs
- Urinary tract
- Sweat glands
Focal Neuropathy
- Eyes
- Facial muscles
- Hearing
- Pelvis and lower back
- Thigh
- Abdomen
What
Are The Major Types Of Neuropathy?
The symptoms of neuropathy also depend on which
nerves and what part of the body is affected. Neuropathy
may be diffuse, affecting many parts of the body,
or focal, affecting a single, specific nerve and part
of the body.
Diffuse Neuropathy
The two categories of diffuse neuropathy are peripheral
neuropathy affecting the feet and hands and autonomic
neuropathy affecting the internal organs.
Peripheral Neuropathy The most common type of peripheral
neuropathy damages the nerves of the limbs, especially
the feet. Nerves on both sides of the body are affected.
Common symptoms of this kind of neuropathy are:
- Numbness or insensitivity to pain or temperature
- Tingling, burning, or prickling
- Sharp pains or cramps
- Extreme sensitivity to touch, even light touch
- Loss of balance and coordination.
These symptoms are often worse at night.
The damage to nerves often results in loss of reflexes
and muscle weakness.
The foot often becomes wider and shorter, the gait
changes, and foot ulcers appear as pressure is put
on parts of the foot that are less protected. Because
of the loss of sensation, injuries may go unnoticed
and often become infected. If ulcers or foot injuries
are not treated in time, the infection may involve
the bone and require amputation. However, problems
caused by minor injuries can usually be controlled
if they are caught in time. Avoiding foot injury by
wearing well-fitted shoes and examining the feet daily
can help prevent amputations.
Autonomic Neuropathy (also called visceral neuropathy)
Autonomic neuropathy is another form of diffuse neuropathy.
It affects the nerves that serve the heart and internal
organs and produces changes in many processes and
systems. Urination and sexual response
Autonomic neuropathy most often affects the organs
that control urination and sexual function. Nerve
damage can prevent the bladder from emptying completely,
so bacteria grow more easily in the urinary tract
(bladder and kidneys).
When the nerves of the bladder are damaged, a person
may have difficulty knowing when the bladder is full
or controlling it, resulting in urinary incontinence.
The nerve damage and circulatory problems of diabetes
can also lead to a gradual loss of sexual response
in both men and women, although sex drive is unchanged.
Digestion
Autonomic neuropathy can affect digestion. 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 greatly with
this condition. 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.
Cardiovascular system
Autonomic neuropathy can affect the cardiovascular
system, which controls the circulation of blood throughout
the body. Damage to this system interferes with the
nerve impulses from various parts of the body that
signal the need for blood and regulate blood pressure
and heart rate. As a result, blood pressure may drop
sharply after sitting or standing, causing a person
to feel dizzy or light-headed, or even to faint (orthostatic
hypotension).
Neuropathy that affects the cardiovascular system
may also affect the perception of pain from heart
disease. People may not experience angina as a warning
sign of heart disease or may suffer painless heart
attacks. It may also raise the risk of a heart attack
during general anesthesia.
Hypoglycemia
Autonomic neuropathy can hinder the body's normal
response to low blood sugar or hypoglycemia, which
makes it difficult to recognize and treat an insulin
reaction. Sweating
Autonomic neuropathy can affect the nerves that control
sweating. Sometimes, nerve damage interferes with
the activity of the sweat glands, making it difficult
for the body to regulate its temperature. Other times,
the result can be profuse sweating at night or while
eating (gustatory sweating).
What
Are The Major Types Of Neuropathy?
The symptoms of neuropathy also depend on which nerves
and what part of the body is affected. Neuropathy may
be diffuse, affecting many parts of the body, or focal,
affecting a single, specific nerve and part of the body.
Focal Neuropathy - (including multiplex neuropathy)
Occasionally, diabetic neuropathy appears suddenly
and affects specific nerves, most often in the torso,
leg, or head. Focal neuropathy may cause:
Pain in the front of a thigh
Severe pain in the lower back or pelvis
Pain in the chest, stomach, or flank
Chest or abdominal pain sometimes mistaken for angina,
heart attack, or appendicitis
Aching behind an eye
Inability to focus the eye
Double vision
Paralysis on one side of the face (Bell's palsy)
Problems with hearing
This kind of neuropathy is unpredictable and occurs
most often in older people who have mild diabetes.
Although focal neuropathy can be painful, it tends
to improve by itself after a period of weeks or months
without causing long-term damage.
People with diabetes are also prone to developing
compression neuropathies. The most common form of
compression neuropathy is carpal tunnel syndrome.
Asymptomatic carpal tunnel syndrome occurs in 20 to
30 percent of people with diabetes, and symptomatic
carpal tunnel syndrome occurs in 6 to 11 percent.
Numbness and tingling of the hand are the most common
symptoms. Muscle weakness may also develop.
How
Do Doctors Diagnose Diabetic Neuropathy?
A doctor diagnoses neuropathy based on 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 also used to help determine
the cause of symptoms and to suggest treatment.
A simple screening test to check point sensation
in the feet can be done in the doctor's office. The
test uses a nylon filament mounted on a small wand.
The filament delivers a standardized 10-gram force
when touched to areas of the foot. Patients who cannot
sense pressure from the filament have lost protective
sensation and are at risk for developing neuropathic
foot ulcers. Physicians may order the filament (with
instructions for use) free from the Gillis W. Long
Hansen's Disease Center, LEAP Program, 5445 Point
Clair Road, Carville,
Louisiana 70721; telephone (504) 642-4714.
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 signal. 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 the nerves in the arms and legs.
Electromyography (EMG) is used to see how well muscles
respond to electrical impulses transmitted by nearby
nerves. The electrical activity of the muscle is displayed
on a screen. A response that is slower or weaker than
usual suggests damage to the nerve or muscle. This
test is often done at the same time as nerve conduction
studies.
Ultrasound employs sound waves. The sound waves
are too high to hear, but they produce an image showing
how well the bladder and other parts of the urinary
tract are functioning.
Nerve biopsy involves removing a sample of nerve
tissue for examination. This test is most often used
in research settings.
If your doctor suspects autonomic neuropathy, you
may also be referred to a physician who specializes
in digestive disorders (gastroenterologist) for additional
tests.
How
Is Diabetic Neuropathy Usually Treated?
Neuropathy treatment tries relieving discomfort
and prevent further tissue damage. The first step
is to bring blood sugar under control by diet and
oral drugs or insulin injections, if needed, and by
careful monitoring of blood sugar levels. Although
symptoms can sometimes worsen at first as blood sugar
is brought under control, maintaining lower blood
sugar levels helps reverse the pain or loss of sensation
that neuropathy can cause. Good control of blood sugar
may also help prevent or delay the onset of further
problems. Another important part of treatment involves
special care of the feet, which are prone to problems.
A number of medications and other approaches are
used to relieve the symptoms of diabetic neuropathy.
Relief of Pain -- For relief of pain, burning, tingling,
or numbness, the doctor may suggest an analgesic such
as aspirin or acetaminophen or anti-inflammatory drugs
containing ibuprofen. Nonsteroidal anti-inflammatory
drugs should be used with caution in people with renal
disease. Antidepressant medications such as amitriptyline
(sometimes used with fluphenazine) or nerve medications
such as carbamazepine or phenytoin sodium may be helpful.
Codeine is sometimes prescribed for short-term use
to relieve severe pain. In addition, a topical cream,
capsaicin, is now available to help relieve the pain
of neuropathy.
The doctor may also prescribe a therapy known as
transcutaneous electronic nerve stimulations (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.
Gastrointestinal Problems -- Indigestion,
belching, nausea or vomiting are symptoms of gastroparesis.
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 helps relieve nausea. Other drugs that help regulate
digestion or reduce stomach acid secretion may also
be used or erythromycine may be prescribed. In each
case, the potential benefits of these drugs need to
be weighed against their side effects.
To relieve diarrhea or other bowel problems, antibiotics
or clonidine HCl, a drug used to treat high blood
pressure, are sometimes prescribed. The antibiotic
tetracycline may be prescribed. A wheat-free diet
may also bring relief since the gluten in flour sometimes
causes diarrhea.
Neurological problems affecting the urinary tract
can result in infections or incontinence. The doctor
may prescribe an antibiotic to clear up an infection
and suggest drinking more fluids to prevent further
infections. If incontinence is a problem, patients
may be advised to urinate at regular times (every
3 hours, for example) since they may not be able to
tell when the bladder is full.
Dizziness, Weakness -- Sitting or standing
slowly may help prevent light-headedness, dizziness,
or fainting, which are symptoms that may be associated
with some forms of autonomic neuropathy. Raising the
head of the 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 certain patients,
drugs used to treat hypertension can instead raise
blood pressure, although predicting which patients
will have this paradoxical reaction is difficult.
Muscle weakness or loss of coordination caused by
diabetic neuropathy can often be helped by physical
therapy.
Urinary and Sexual Problems -- Nerve and
circulatory problems of diabetes can disrupt normal
male sexual function, resulting in impotence. After
ruling out a hormonal cause of impotence, the doctor
can provide information about 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 semirigid device
is implanted in the penis, offer a more permanent
solution. For some people, counseling may help relieve
the stress caused by neuropathy and thereby help restore
sexual function.
In women who feel their sexual life is not satisfactory,
the role of diabetic neuropathy is less clear. Illness,
vaginal or urinary tract infections, and anxiety about
pregnancy complicated by diabetes can 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 need to take special care of
their feet. Neuropathy and blood vessel disease both
increase the risk of foot ulcers. The nerves to the
feet are the longest in the body, and are most often
affected by neuropathy. Because of the loss of sensation
caused by neuropathy, sores or injuries to the feet
may not be noticed and may become ulcerated.
At least 15 percent of all people with diabetes eventually
have a foot ulcer, and 6 out of every 1,000 people
with diabetes have an amputation. However, doctors
estimate that nearly three quarters of all amputations
caused by neuropathy and poor circulation could be
prevented with careful foot care. To prevent foot
problems from developing, people with diabetes should
follow these rules for foot care:
Check your feet and toes daily for any cuts, sores,
bruises, bumps, or infections, use a mirror if necessary.
Wash your feet daily, using warm water and mild soap.
If you have neuropathy, you should test the water
temperature with your wrist before putting your feet
in the water. We 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 the 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. In
people with diabetes, the feet tend to sweat less
than normal. Using a moisturizer helps prevent 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 at first.
After years of neuropathy, reflexes decline, and
feet are likely to become wider and flatter. If you
have difficulty finding shoes that fit, ask your doctor
to refer you to a specialist, called a pedorthist,
who can provide you with corrective shoes or inserts.
Examine your shoes before putting them on to make
sure they have no tears, rough areas or sharp edges,
or objects in them that might injure your feet. Never
go barefoot, especially on the beach, hot sand, or
rocks. 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 pumice stone to file away dead
skin, but do not remove calluses, which act as protective
padding. Do not try to cut-off any growths yourself,
and avoid using harsh chemicals such as wart remover
on your feet.
Test the water temperature with your elbow before
stepping in a bath. If your feet are cold at night
wear socks. (Do not use heating pads or hot water
bottles.)
Avoid sitting with your legs crossed. Crossing your
legs 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 is not
healing well.
If you are 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.
Are
There Any Experimental Treatments For Diabetic Neuropathy?
Several new drugs under study may eventually prevent
or reverse diabetic neuropathy. However, 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.
Researchers are exploring treatment with a compound
called myoinositol. Early findings have shown that
nerves in diabetic animals and humans have less than
normal amounts of this substance.
Myoinositol supplements increase the levels of this
substance in tissues of diabetic animals, but research
is still needed to show any concrete lasting benefits
from this treatment.
Another area of research concerns the drug aminoguanidine.
In animals, this drug blocks cross-linking of proteins
that occurs more quickly than normal in tissues exposed
to high levels of glucose. 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 (ARIs). ARIs 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 that these drugs have major side effects
and, consequently, they are not available for clinical
use.
Some General Hints
Ask your doctor to suggest an exercise routine that
is right for you. Many people who exercise regularly
find the pain of neuropathy less severe.
Aside from helping you reach and maintain a healthy
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.
If you smoke, try to stop because smoking makes circulatory
problems worse and increases the risk of neuropathy
and heart disease. Reduce the amount of alcohol you
drink. Recent research has indicated that as few as
four drinks per week can worsen neuropathy. Take special
care of your feet!
What
Resources Are Available For People With Diabetic Neuropathy?
American Association of Diabetes Educators
444 N. Michigan Avenue
Suite 1240
Chicago, IL 60611
800-832-6874 or 312-644-2233
A professional organization that can help individuals
locate a diabetes educator in their community.
American Diabetes Association National Service Center
1660 Duke Street
Alexandria, VA 22314
800-232-3472 or 703-549-1500
A private, voluntary organization that fosters public
awareness of diabetes and supports and promotes diabetes
research and education. The 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
800-877-1600 or 312-899-0040
Professional organization which can help individuals
locate a registered dietitian in their community.
American Heart Association
7320 Greenville Avenue
Dallas, TX 75231
800-242-1793
A private, voluntary organization distributing literature
on heart disease and how to prevent it. Local affiliates
can be found in your local telephone directory.
Juvenile Diabetes Foundation International
381 Park Ave S Ste 507
New York, NY 10016
1-212-689-2860 or 1-800-223-1138
Private, voluntary organization that funds research
on diabetes and promotes> public awareness. Local
chapters located across the country sponsor programs
and fund-raising activities. Information about local
groups is available in telephone directories or from
the national office.
National Diabetes Information Clearinghouse
1 Information Way
Bethesda, MD 20892
301-654-3327
Program of the National Institute of Diabetes and
Digestive and Kidney Diseases, the Federal Government's
lead agency for diabetes research. The institute distributes
several publications to the public and to health professionals.
Diabetic
Neuropathy.org & Diabetic-Neuropathy.org
Diabetes
