Diabetic Neuropathy
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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.
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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:
- metabolic factors, such as high blood glucose, long duration
of diabetes, possibly 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
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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
- 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
- diarrhea or constipation
- dizziness or faintness due to a drop in postural blood
pressure
- problems with urination
- erectile dysfunction (impotence) or vaginal dryness
- weakness
In addition, the following symptoms are not due to neuropathy but
nevertheless often accompany it:
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Diabetic neuropathies can 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 can also
affect the nerves that serve the heart and control blood pressure.
Autonomic neuropathy can also cause hypoglycemia (low blood sugar)
unawareness, a condition in which people no longer experience the
warning signs of hypoglycemia.
- 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.
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Peripheral
Neuropathy
- toes
- feet
- legs
- hands
- arms
Autonomic Neuropathy
- heart and blood vessels
- digestive system
- urinary tract
- sex organs
- sweat glands
- eyes
Proximal Neuropathy
Focal Neuropathy
- eyes
- facial muscles
- ears
- pelvis and lower back
- thighs
- abdomen
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| 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
- numbness or insensitivity to pain or temperature
- a tingling, burning, or prickling sensation
- sharp pains or cramps
- extreme sensitivity to touch, even a light touch
- loss of balance and coordination
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.
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| 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-headed--or 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.
Digestive System
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.
Sweat Glands
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.
Eyes
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.
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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.
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Occasionally, diabetic neuropathy appears suddenly and affects
specific nerves, most often in the head, torso, or leg. Focal
neuropathy may cause
- inability to focus the eye
- double vision
- aching behind one eye
- paralysis on one side of the face (Bell's palsy)
- severe pain in the lower back or pelvis
- pain in the front of a thigh
- pain in the chest, stomach, or flank
- pain on the outside of the shin or inside the foot
- chest or abdominal pain that is sometimes mistaken for heart
disease, heart attack, or appendicitis
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.
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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.
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.
- A comprehensive foot exam assesses skin,
circulation, and sensation. The test can be done during a routine
office visit. To assess protective sensation or feeling in the
foot, a nylon monofilament (similar to a bristle on a hairbrush)
attached to a wand is used to touch the foot. Those who cannot
sense pressure from the monofilament have lost protective
sensation and are at risk for developing foot sores that may not
heal properly. Other tests include checking reflexes and assessing
vibration perception, which is more sensitive than touch
pressure.
- Nerve conduction studies check the transmission
of electrical current through a nerve. With this test, an image of
the nerve conducting an electrical signal is projected onto a
screen. Nerve impulses that seem slower or weaker than usual
indicate possible damage. This test allows the doctor to assess
the condition of all the nerves in the arms and legs.
- Electromyography (EMG) shows how well muscles
respond to electrical signals 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.
- Quantitative sensory testing (QST) uses the
response to stimuli, such as pressure, vibration, and temperature,
to check for neuropathy. QST is increasingly used to recognize
sensation loss and excessive irritability of nerves.
- A check of heart rate variability shows how the
heart responds to deep breathing and to changes in blood pressure
and posture.
- Ultrasound uses sound waves to produce an image
of internal organs. An ultrasound of the bladder and other parts
of the urinary tract, for example, can show how these organs
preserve a normal structure and whether the bladder empties
completely after urination.
- Nerve or skin biopsy involves removing a sample
of nerve or skin tissue for examination by microscope. This test
is most often used in research settings.
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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.
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.
More than half of all lower limb amputations in the United States
occur in people with diabetes--86,000 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:
- Clean your feet daily, using warm--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. Use a mirror
(laying a mirror on the floor works well) or get help from someone
else if you cannot see the bottoms of your feet. Notify your
health care provider of any 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 and file the edges with an emery board.
- 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. Break in
new shoes gradually by wearing them for only an hour at a time at
first.
- 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.
- If you need help taking care of your feet, make an appointment
to see a foot doctor, also called a podiatrist.
Pain Relief
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.
Gastrointestinal Problems
To relieve mild symptoms of gastroparesis--indigestion, belching,
nausea, or vomiting--doctors 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.
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- Diabetic neuropathies are nerve disorders caused by many of
the abnormalities common to diabetes, such as high blood
glucose.
- Neuropathy can affect nerves throughout the body, causing
numbness and sometimes pain in the hands, arms, feet, or legs, and
problems with the digestive tract, heart, and sex organs.
- Treatment first involves bringing blood glucose levels within
the normal range. Good blood glucose control may help prevent or
delay the onset of further problems.
- Foot care is another important part of treatment. People with
neuropathy need to inspect their feet daily for any injuries.
Untreated injuries increase the risk of infected foot sores and
amputation.
- Treatment also includes pain relief and other medications as
needed, depending on the type of nerve damage.
- Smoking significantly increases the risk of foot problems and
amputation. If you smoke, ask your health care provider for help
in quitting.
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American Diabetes Association
American Foundation for Urologic
Disease
Centers for Disease
Control and Prevention
Juvenile Diabetes Research
Foundation International
National Diabetes Education Program
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