Dealing with Diabetic Neuropathy

Definition

 

Neuropathy is the medical term for nerve damage. Diabetic neuropathy is a common complication of type 1 and type 2 diabetes; up to 26 percent of people with type 2 diabetes have evidence of nerve damage at the time their diabetes is diagnosed.

High blood sugar can injure nerve fibers throughout your body, but nerves in your legs and feet are damaged most often.

Depending on the affected nerves, symptoms of diabetic neuropathy can range from pain and numbness in your extremities to problems with your digestive system, urinary tract, blood vessels and heart. For some people, these symptoms are mild; for others, diabetic neuropathy can be painful, disabling and even fatal.

Diabetic neuropathy is a very serious complication of diabetes. Yet you can often prevent diabetic neuropathy or slow its progress with tight blood sugar control and a healthy lifestyle.

Symptoms

There are four main types of diabetic neuropathy. You may have just one type or symptoms of several types. Most develop gradually, and you may not notice problems until considerable damage has occurred. For some people, symptoms of neuropathy develop before diabetes is ever diagnosed.

The signs and symptoms of diabetic neuropathy vary, depending on the type of neuropathy and which nerves are affected:

Peripheral Neuropathy

Peripheral neuropathy is the most common form of diabetic neuropathy. It damages nerves in your feet, legs, arms and hands, but your legs and feet are affected most often.

The most common symptoms of diabetic peripheral neuropathy include:

• Some people initially have intensely painful feet while others have few or no symptoms.
• Numbness, or reduced ability to feel pain or changes in temperature, especially in your toes or feet
• Extreme sensitivity to the lightest touch — for some people, even the weight of a sheet can be agonizing
• A tingling, burning or prickling sensation that starts in your toes or the balls of your feet and gradually spreads upward
• Sharp, jabbing or electric shock-like pain that's worse at night and at rest and improve with activity, such as walking.
• Loss of balance and coordination
• Muscle weakness and difficulty walking

Diabetic neuropathy usually affects both sides of the body. Symptoms are usually noticed first in the toes. If the disease progresses, symptoms may gradually move up the legs; if the mid-calves are affected, symptoms may develop in the hands. Over time, the ability to sense pain may be lost, which greatly increases the risk of injury.

Autonomic Neuropathy

The autonomic nervous system controls your heart, bladder, lungs, stomach, intestines, sex organs and eyes. Diabetes can affect the nerves in any of these areas, causing

• Bladder problems, including frequent urinary tract infections or urinary incontinence
• Digestive problems, such as bloating, belching and abdominal pain
• Constipation, uncontrolled diarrhea or a combination of the two
• Slow stomach emptying (gastroparesis), leading to nausea, vomiting and loss of appetite
• Erectile dysfunction, which affects more than half the men with diabetes who are age 60 or older
  Vaginal dryness and other sexual difficulties in women
• Increased or decreased sweating
• Inability of your body to adjust blood pressure and heart rate, leading to sharp drops in blood pressure after sitting or standing (orthostatic hypotension)
• Problems regulating your body temperature
• Changes in the way your eyes adjust from light to dark

Autonomic neuropathy is most likely to occur in people who have had poorly-controlled diabetes for many years.

Proximal Neuropathy

Also called femoral neuropathy or diabetic amyotrophy, proximal neuropathy is often marked by severe pain in your hip and thigh or buttocks, usually beginning on one side of your body. Eventually, your thigh muscles become weak and atrophied, making it difficult to rise from a sitting position. Many people have severe weight loss as well. Another form of this disorder causes severe pain in the trunk of your body. Proximal neuropathy mainly affects older adults and people with type 2 diabetes.

Focal Neuropathy

Focal neuropathy often comes on suddenly and usually involves a single nerve. It's most common in older adults. Although focal neuropathy can cause severe pain, it usually goes away on its own in a few weeks or months. Signs and symptoms include:

• Difficulty focusing your eyes, double vision or aching behind one eye
• Paralysis on one side of your face (Bell's palsy)
• Pain in your shin or foot
• Sometimes focal neuropathy occurs when a nerve is compressed. Carpal tunnel syndrome is the most common type of compression neuropathy in people with diabetes. Signs and symptoms of carpal tunnel syndrome include:
  
  
  • Numbness, swelling or tingling in your fingers when driving a car or holding a newspaper
  • Pain radiating or extending from your wrist up your arm to your shoulder or down into your palm or fingers, especially after forceful or repetitive use
  • A sense of weakness in your hands and a tendency to drop objects

Causes

A complex system of nerves runs through your body, connecting your brain to your muscles, skin and other organs. Through these nerves, your brain senses pain and temperature, controls your muscles, and performs automatic tasks such as digestion.

• High Blood Sugar
  
  Prolonged exposure to high blood sugar (glucose) can damage delicate nerve fibers, but exactly why this happens isn't completely clear. It's likely that a combination of factors plays a role, including the complex interaction between nerves and blood vessels. High blood glucose interferes with the ability of the nerves to transmit signals. It also weakens the walls of the small blood vessels (capillaries) that supply the nerves with oxygen and nutrients.
• Protein glycation. This occurs when sugars in your body react with proteins, altering the nature of the proteins. Glycated proteins have been linked to aging and to complications of diabetes, including diabetic neuropathy.
• Inflammation in the nerves caused by an autoimmune response. This occurs when your immune system mistakenly attacks part of your body as if it were a foreign organism.
• Genetic factors unrelated to diabetes that make some people more susceptible to nerve damage.
• Smoking and alcohol abuse, which damage both nerves and blood vessels and significantly increase the risk of infections.

Risk Factors

Anyone who has diabetes can develop neuropathy, but these factors make you more susceptible to nerve damage:

• Poor blood sugar control. This is the greatest risk factor for every complication of diabetes, including nerve damage. In people with type 1 diabetes, nerve damage can occur within 5 to 10 years of being diagnosed with diabetes, while in people with type 2 diabetes, neuropathy can be present even before the condition is detected. Keeping blood sugar consistently within your target range is the best way to protect the health of your nerves and blood vessels.
• Length of time you have diabetes. Your risk of diabetic neuropathy increases the longer you have diabetes, especially if your blood sugar isn't well controlled. Autonomic neuropathy, which can affect digestion and bladder and sexual functioning, occurs mainly in people who have had poorly-controlled diabetes for two decades or more. And the highest rates of peripheral neuropathy occur in people who have had diabetes for at least 25 years.
• Age. The older you are, the greater your chance of developing diabetic neuropathy.
• Your sex. Men are more likely to have diabetic neuropathy than women are.
• High cholesterol. A high level of low-density lipoprotein (LDL) cholesterol (the "bad" cholesterol) damages the small blood vessels that nourish your nerves.
• Smoking. Smoking narrows and hardens your arteries, reducing blood flow to your legs and feet. This makes it more difficult for wounds to heal and damages the integrity of the peripheral nerves.

Other factors can further increase the risk of developing neuropathy, including

• Coronary artery disease
• Being overweight (a body mass index >25)
• High blood pressure

When to Seek Medical Advice

Seek medical care if you notice

• Unusual burning, tingling weakness or pain in your hands or feet
• Dizziness
• Markedly increased or decreased sweating
• Changes in your digestion, urination or sexual function

These symptoms don't always indicate nerve damage, but they may signal other problems that require medical care. In either case, early diagnosis and treatment offer the best chance for controlling symptoms and preventing more-severe problems.

See your doctor immediately if you have a cut or sore on your foot that doesn't seem to be healing, is infected or is getting worse. Even minor sores that don't heal can turn into ulcers. In the most severe cases, untreated foot ulcers may become gangrenous — a condition in which the tissue dies — and require surgery or even amputation of your foot.

Diagnosis

Diabetic neuropathy is usually diagnosed based on your symptoms, your medical history and a physical exam.

During the exam, your doctor is likely to check your muscle strength and tone, tendon reflexes, sensitivity to light touch, pain, temperature, vibration, and directional movement in the toes (e.g., when the toe is moved up or down)

The American Diabetes Association recommends that all people with diabetes have a comprehensive foot exam — either by a doctor or a foot specialist (podiatrist) — at least once a year. In addition, your feet should be checked for sores, cracked skin, calluses, blisters, and bone and joint abnormalities at every office visit (usually every 3 to 4 months). If you already have diabetic neuropathy, you'll likely be referred to a podiatrist or other specialist for monitoring and treatment.

Filament Test

Sensitivity to touch is often tested using a soft nylon monofilament. If you're unable to feel the filament on your feet, it's a sign that you've lost sensation in those nerves.

Other Tests

More extensive testing, including nerve conduction studies, nerve biopsy, or imaging tests (e.g., x-ray or CT scan), is not usually needed to diagnose diabetic neuropathy.

In some cases, other tests may be needed, including:

• Nerve conduction studies. This test measures how quickly the nerves in your arms and legs conduct electrical signals. It's often used to diagnose carpal tunnel syndrome.
• Electromyography (EMG) Often performed along with nerve conduction studies, electromyography measures the electrical discharges produced in your muscles.
• Quantitative sensory testing. This noninvasive test is used to assess how your nerves respond to vibration and changes in temperature.

Complications 

Diabetic neuropathy can cause a number of serious complications, including

• Loss of a limb. Because nerve damage can cause a lack of feeling in your feet, cuts and sores may go unnoticed and eventually become severely infected or ulcerated — a condition in which the skin and soft tissues break down. The risk of infection is high because diabetes reduces blood flow to your feet. Infections that spread to the bone and cause tissue death (gangrene) may be impossible to treat and require amputation of a toe, foot or even the lower leg. More than half the nontraumatic lower limb amputations performed every year in the United States are due to diabetes.
• Charcot joint. This occurs when a joint, usually in the foot, deteriorates because of nerve damage. Charcot joint is marked by a loss of sensation, as well as swelling, instability and sometimes deformity in the joint itself.
• Urinary tract infections and urinary incontinence. Damage to the nerves that control your bladder can prevent it from emptying completely. This allows bacteria to grow in your bladder and kidneys, leading to urinary tract infections. Nerve damage can also affect your ability to sense when you need to urinate or to control the muscles that release urine.
• Hypoglycemia unawareness. Normally, when your blood sugar drops too low (below 70 milligrams per deciliter (mg/dL), or below 3.0 millimoles per liter (mmol/L)) you develop symptoms such as shakiness, sweating and a fast heartbeat. These symptoms alert you to the problem so that you can take steps to raise your blood sugar quickly. Autonomic neuropathy can interfere with your ability to notice these symptoms. This is extremely serious — untreated hypoglycemia can be fatal.
• Low blood pressure. Damage to the nerves that control circulation can affect your body's ability to adjust blood pressure. This can cause a sharp drop in pressure when you stand after sitting (orthostatic hypotension), which may lead to dizziness and fainting.
• Digestive problems. Nerve damage to the digestive system can cause a range of problems, including severe constipation or diarrhea — or alternating bouts of constipation and diarrhea — as well as nausea, vomiting, bloating and loss of appetite. One particularly serious digestive problem is gastroparesis, a condition in which the stomach empties too slowly or not at all. This can interfere with digestion, cause nausea and vomiting, and severely affect blood sugar levels and nutrition.
• Sexual dysfunction Autonomic neuropathy often damages the nerves that affect the sex organs, leading to erectile dysfunction in men and problems with lubrication and arousal in women.
• Increased or decreased sweating. When the sweat glands don't function normally, your body isn't able to regulate its temperature properly. A reduced or complete lack of perspiration (anhidrosis) can be life-threatening. More often, autonomic neuropathy causes excessive sweating, particularly at night.
• Social isolation The pain, disability and embarrassment caused by nerve damage can rob people — particularly older adults — of their independence, leaving them increasingly isolated and depressed.

Treatment

 

Diabetic neuropathy has no known cure. Treatment for diabetic neuropathy focuses on:

• 
  
  Relieving pain
• Managing complications
• Restoring function

Slowing Disease Progression

One of the most important treatments for diabetic neuropathy is to control blood glucose levels. Consistently keeping blood sugar within a narrow target range can help delay the progression of peripheral neuropathy and may even cause an improvement in symptoms you already have. In some people, intense glucose control may reduce the overall risk of diabetic neuropathy by more than 60 percent.

For intense blood sugar control, your goals will likely be:

• Blood sugar level before meals 90 to 130 mg/dL (5 to 7 mmol/L)
• Blood sugar level two hours after meals less than 180 mg/dL (10 mmol/L)
• Hemoglobin A1C (an indicator of your blood sugar control over the past 3 months) less than 7 percent. A1C is the amount of sugar that has bound to hemoglobin (the substance that carries oxygen inside red blood cells) in your blood. The higher your average blood sugar level for the past two or three months, the higher your A1C number will be. People who don't have diabetes have an A1C between 4 percent and 6 percent.

The American Diabetes Association recommends that people with diabetes have an A1C test at least twice a year if blood sugar levels are consistently in a healthy range. If your blood sugar isn't well controlled or you change medications, you should be tested more often.

If blood glucose levels are not adequately controlled with the current treatment regimen, a different regimen may be recommended. For people with type 1 diabetes, this may mean taking more frequent insulin injections or using an insulin pump. For people with type 2 diabetes, this may mean taking an additional oral medication or starting insulin injections.

Relieving Pain

Neuropathic pain can be difficult to control and can seriously affect a person's quality of life. Neuropathic pain is often worse at night, seriously disrupting sleep.

Fortunately, only a small percentage of people with diabetic neuropathy experience pain. Pain resolves without treatment in some people over a period of weeks to months, especially if the episode of pain developed after a sudden change in health (e.g., an episode of diabetic ketoacidosis, a significant weight loss, or a significant change in blood glucose control).

Several medications are used to relieve nerve pain, but they don't work for everyone and most have side effects that must be weighed against the benefits they offer.

• Anti-seizure medications. Drugs such as gabapentin (Neurontin), pregabalin (Lyrica) and carbamazepine (Tegretol) were originally developed to treat seizure disorders (epilepsy), but they're also prescribed for nerve pain.
• Gabapentin (Neurontin®): It is usually taken by mouth three times per day. Side effects can include dizziness and confusion. Gabapentin can be taken with a TCA or duloxetine. In some cases, a large dose of gabapentin can be taken at night to help with sleep.
• Pregabalin (Lyrica®): It is similar to gabapentin. Pregabalin is taken by mouth, starting at bedtime at a low dose, and then gradually increasing to three times per day over a period of several weeks.

Side effects can include dizziness, sleepiness, confusion, swelling in the feet and ankles, and weight gain. It may be possible to become addicted to pregabalin, and changes in dosing should be monitored carefully. Pregabalin can be taken with duloxetine or TCAs, but not with gabapentin.

• Tricyclic antidepressants — There are several tricyclic antidepressants (TCAs) available for the treatment of chronic pain, including amitriptyline, nortriptyline, imipramine and desipramine. The dose of TCA used to treat neuropathy is much lower than that used to treat depression. TCAs may provide relief for mild to moderate symptoms by interfering with chemical processes in your brain that cause you to feel pain, but they also cause a number of side effects. TCAs are usually taken at bedtime, starting with a low dose and gradually increasing over a period of several weeks. People with heart disease should not take amitriptyline or nortriptyline. TCAs can be taken with gabapentin and pregabalin, but should not be taken with duloxetine. Side effects can include dry mouth, sleepiness, dizziness, and constipation.

• Selective serotonin reuptake inhibitors (SSRIs), such as paroxetine and fluoxetine hydrochloride, have fewer side effects but work less well for pain. Newer antidepressants called serotonin and norepinephrine reuptake inhibitors (SNRIs) are often a better choice, relieving pain with few side effects.
• Duloxetine (Cymbalta®): is an antidepressant that is often effective in relieving pain caused by diabetic neuropathy. In short-term clinical trials, duloxetine was more effective than placebo. However, the long-term effectiveness and safety of duloxetine for diabetic neuropathy is uncertain. There are no trials comparing duloxetine with other drugs for the treatment of diabetic polyneuropathy.

Duloxetine is usually taken by mouth once per day on a full stomach, although in some cases it is taken twice per day. It should not be taken by people who take other antidepressant medications. Side effects can include nausea, sleepiness, dizziness, decreased appetite, and constipation.

• Tramadol (Ultram®): is a pain medication that can be taken for breakthrough pain; in severe cases, it can be taken every 6 hours (4 times per day). It can cause sedation, dizziness and confusion. It can be taken with pregabalin, duloxetine, gabapentin and TCAs.
• Lidocaine patch: Lidocaine is an anesthetic drug that may be recommended if other treatments have not improved pain. You apply it to the area where your pain is most severe. The patch slowly releases the medication over time. Up to four patches may be applied for up to 18 hours per day. It has almost no side effects, although it may cause a rash in some people.
• Alpha-lipoic acid: One of the most interesting developments in pain research is the discovery that alpha-lipoic acid, a powerful antioxidant found in food, may be effective at relieving the symptoms of peripheral neuropathy. Studies used an intravenous form of ALA, which isn't yet available, however, and researchers caution that it's not known whether over-the-counter supplements have the same effect. Several short-term trials showed that it was helpful in relieving pain caused by diabetic neuropathy. Thus, ALA may be recommended to people with diabetic neuropathy who do not improve with or who cannot tolerate other treatments. However, longer-term studies are still needed to confirm its safety and effectiveness. In the United States, ALA is available without a prescription as a dietary supplement. It is usually taken by mouth once per day.

• Capsaicin: This is the chemical that gives hot peppers their bite. When applied to the skin, capsaicin creams can reduce pain sensations in some people.
• Opioid analgesics, such as codeine or oxycodone may be used to relieve pain. But this class of medications may produce serious side effects, including addiction, that make long-term use of them undesirable.

Other Types of Therapy

Several drug-free therapies and techniques also may help with pain relief. Doctors frequently use them in conjunction with medications, but some may be effective on their own. They include:

• Transcutaneous electrical nerve stimulation (TENS). Your doctor may prescribe this therapy, which can help prevent pain signals from reaching your brain. TENS delivers tiny electrical impulses to specific nerve pathways through small electrodes placed on your skin. Although safe and painless, TENS doesn't work for everyone or for all types of pain.
• Biofeedback. This therapy uses a special machine to teach you how to control certain body responses that reduce pain. You then learn how to control these same responses yourself. Biofeedback techniques are often taught in medical centers and hospitals.
• Acupuncture. The National Institutes of Health has found that acupuncture can be an effective treatment for chronic pain, possibly including the pain of neuropathy. Keep in mind that you may not get immediate relief with acupuncture and will likely require more than one session.
• Hypnosis. Many adults can be hypnotized by a trained professional, but for hypnosis to be most effective, you also have to be a willing and motivated participant. During hypnosis, you'll typically receive suggestions intended to decrease your perception of pain.
• Relaxation techniques. Designed to help reduce the muscle tension that makes pain worse, relaxation techniques range from deep-breathing exercises to visualization (imagining yourself floating in a tropical ocean, for example), yoga and meditation. You might want to take classes in one or more of these techniques, or you can learn them yourself using books or tapes.

Managing Complications

 

Specific treatments exist for many of the complications of neuropathy, including:

• Urinary tract problems. Antispasmodic medications (anticholinergics), behavioral techniques such as timed urination, and devices such as pessaries — rings inserted into the vagina to prevent urine leakage — may be helpful in treating loss of bladder control. Often, a combination of therapies may be most effective.
• Digestive problems. Gastroparesis can usually be helped by eating smaller, more frequent meals, reducing fiber and fat in the diet, and, for many people, eating soups and pureed foods. Diarrhea, constipation and nausea may be helped with dietary changes and medications.
• Low blood pressure on standing (orthostatic hypertension). This is often helped with simple lifestyle measures, such as avoiding alcohol, drinking plenty of water and standing up slowly. Several medications, either alone or together, also may be used to treat orthostatic hypotension. For example, the drug fludrocortisone helps boost your blood volume, which in turn raises blood pressure.
• Sexual dysfunction. Sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra) can improve sexual function in some men, but these medications aren't effective or safe for everyone. When medications don't work, many men turn to vacuum devices, or, if these fail, to penile implants. Women may be helped with vaginal lubricants and estrogen creams.

Prevention

You can help prevent or delay diabetic neuropathy and its complications by keeping your blood sugar consistently well controlled, taking good care of your feet and following a healthy lifestyle.

Blood Sugar Control

Keeping your blood sugar tightly controlled every day is a big commitment. It requires constant monitoring and, if you take insulin, frequent doses of medication. But keeping your blood sugar as close to normal as possible is the best way to help prevent neuropathy and other complications of diabetes. Consistency is important because shifts in blood sugar levels can accelerate nerve damage.

Foot Care

Foot problems, including sores that don't heal, ulcers and even amputation, are the most common complication of diabetic neuropathy. But many of these problems can be prevented by having a comprehensive foot exam at least once a year, having your doctor check your feet at each office visit and taking good care of your feet at home.

To protect the health of your feet:

• Check your feet every day. People with neuropathy do not always feel pain when there is a wound or injury on the foot. As a result, daily foot care is necessary to monitor for changes in the skin (such as cracks or wounds), which can increase the risk of infection. Check the entire surface of both feet for skin breaks, blisters, swelling, or redness, including between and underneath the toes where damage may be hidden. If you can't see some parts of your feet, use a mirror or ask a family member or friend to examine those areas. Look for blisters, cuts, bruises, cracked and peeling skin, and redness and swelling.
• Keep your feet clean and dry. Wash your feet every day with lukewarm water and mild soap. If your feet can't sense temperature, test the water by touching a dampened washcloth to a sensitive part of your body, such as your neck or wrist. Dry your feet gently by blotting or patting. Rubbing may damage your skin. Dry carefully between your toes. Then moisturize your skin thoroughly to prevent cracking.
• Trim your toenails carefully. Trim the toe nails along the shape of the toe and file the nails to remove any sharp edges. Never cut (or allow a manicurist to cut) the cuticles. Do not open blisters, try to free ingrown toenails, or otherwise break the skin on the feet. See a healthcare provider or podiatrist for even minor procedures. If you're not able to reach your feet, ask a family member, your doctor or a podiatrist to help you.
• Wear clean, dry socks. You don't need to buy special socks for people with diabetes, but do look for socks made of cotton or moisture-wicking fibers that don't have tight bands or thick seams. Select socks that fit loosely, and change socks every day.
• Wear shoes that fit well. Always wear shoes to protect your feet from injury. Make sure that your shoes fit properly and are not tight. Break new shoes in slowly to prevent blisters. It's best to try on shoes later in the day when your feet are more swollen to ensure that the shoes aren't too tight. A podiatrist can teach you how to buy properly fitted shoes and to prevent problems such as corns and calluses. Ask about customized shoes if the feet are misshapen or have ulcers; specialized shoes can reduce the chances of developing foot ulcers in the future. Shoe inserts may also help cushion the step and decrease pressure on the soles of the feet.
• Avoid activities that can injure the feet. Some activities increase the risk of foot injury and are not recommended, including walking barefoot, using a heating pad or hot water bottle on the feet, and stepping into the bathtub before testing the temperature with the hand.
• Ask for foot exams — Screening for foot complications should be a routine part of most medical visits, but is sometimes overlooked. At each visit, the shoes and socks should be removed and the clinician should visually examine the feet. Do not hesitate to ask the healthcare provider for a complete foot check at least once a year, and more frequently if there are problems.

If problems do occur, a podiatrist can help treat them to prevent more-serious conditions from developing. Even small sores can quickly turn into severe infections if left untreated. Shoes that fit well can be costly.

Lifestyle Choices

These measures also can help reduce your risk of diabetic neuropathy:

• Keep your blood pressure under control. People with diabetes are about twice as likely to have high blood pressure as people who don't have diabetes. Having both high blood pressure and diabetes greatly increases your risk of complications because both damage your blood vessels and reduce blood flow. Try to keep your blood pressure in the range your healthcare provider recommends, and be sure to have it checked at every office visit. Also consider checking it regularly at home.
• Make healthy food choices. Eat a balanced diet that includes a variety of healthy foods — especially fruits, vegetables and whole grains — and limit portion sizes to help achieve or maintain a healthy weight.
• Be active every day. In addition to helping you achieve a healthy weight, daily activity protects your heart and improves blood flow. It also plays a major role in keeping your blood sugar and blood pressure under control.
• Stop smoking. If you have diabetes and use tobacco in any form, you're more than twice as likely as nonsmokers with diabetes to die of heart attack and stroke. And you're more likely to develop circulation problems in your feet. If you use tobacco, talk to your doctor about ways to quit.
• Follow your doctor's recommendations for good foot care
• Maintain a healthy weight
• Avoid alcohol entirely or, if drinking is allowed, have no more than one drink a day if you're a woman and no more than two drinks a day if you're a man.