What is diabetic neuropathy?
Some diseases consume the body like wildfire. Others are more like a slow burn. Diabetes is a malady that takes its time. If not controlled, diabetes slowly eats away at the body's cells, especially nerve cells. Doctors call the gradual breakdown of nerve cells "neuropathy." At first, nobody misses a few dead cells here and there. But after a decade or two, the damage can be impossible to ignore. Many patients suffer numbness or the opposite, extreme pain. As a result of decreased sensation, many people with diabetes may not be aware when they've broken the skin or suffered a cut or scrape on one of their feet. Bacteria can then set up housekeeping -- an invasion aided by impaired circulation and small vessel disease caused by diabetes. In some cases, these unnoticed infections can lead to raging infections and loss of the limb.
Despite many recent advances in diabetes treatment, neuropathy remains frighteningly common. About 60 to 70 percent of people with either type 1 or type 2 diabetes will eventually develop nerve damage, though not all of them will have symptoms.
But if you have diabetes, remember this: the key to avoiding nerve damage is prevention. By carefully controlling your blood sugar, you can help keep your nerve cells out of harm's way.
What causes diabetic neuropathy?
When people with diabetes experience pain, tingling, numbness or other sensory symptoms, typically in the feet, high blood sugar seems to be the real culprit. In general, nerve cells only start dying when blood sugar stays too high over a long period of time. Nobody knows why extra sugar is so toxic. Perhaps it upsets the chemical balance in the nerves. Or perhaps the sugar slows down blood circulation and cuts off the oxygen supply to the nervous system. Experts speculate that the small blood vessels of the nerves may be damaged, and that proteins within the nervous system may become coated with sugar and not function properly.
The good news is that keeping your blood glucose (sugar) under control will help protect you against neuropathy. In addition, many other risk factors are under your control, including high cholesterol level and blood pressure, smoking, and heavy alcohol use -- all of which increase the likelihood of diabetes-related nerve damage. To protect yourself, don't smoke (and if you do, quit). Drink moderately, if at all, and talk to your doctor about how to bring your cholesterol and blood pressure within a normal range. Risk factors you can't control include your age, heredity, height, and how long you've had diabetes.
What are the symptoms of neuropathy?
It depends what kind of neuropathy you have, but symptoms often include pain, increased sensitivity, numbness, tingling, and decreased sensation in your feet. Hands or other parts of your body can be involved as well, but much less often. You may suffer from severe leg cramps at night, or feel as if your feet are sunburned even in the dead of winter. One or both of your feet may be swollen and warm to the touch. Some types of neuropathy can also lead to impotence (in men), frequent urinary tract infections, or nausea, bloating, and constipation.
What are the types of neuropathy?
These are the major types of diabetic neuropathy:
Distal symmetrical polyneuropathy. This is the most common diabetes-related nerve damage. The two main symptoms are decreased sensation -- which you may not even notice -- and pain, including numbness, tingling, deep aching, and increased sensitivity.
The nerves that carry sensations from the fingers, toes, and feet are usually the first to succumb to neuropathy. At first, a person may feel intense pain in these areas. The skin may become so sensitive that even the weight of a sheet can bring sheer agony. Over time, the pain fades and gives way to numbness. Many people also develop leg cramps, especially at night, as the nerves that control the muscles are damaged and may cause spasms.
In some cases, the joints in the feet can break down, causing a condition known as Charcot foot. As the nerves supplying the muscles with information are damaged, the muscles don't hold the joints in proper alignment, and as sensation decreases, there is no feedback to the muscles to correct it. This, in turn, means that the joints begin to break down and be unable to support the body properly. (The early symptoms of Charcot foot are swelling, redness, and a foot that feels warm to the touch.)
Ischemic neuropathy. This occurs when blood vessels are damaged or clogged and the nerves can't get the oxygen they need. It comes on suddenly and usually affects just one area of the body, such as the head, thigh, or trunk. This kind of neuropathy tends to clear up by itself in a few days or weeks -- although damage to the thighs may last months or even years.
Entrapment neuropathy. This is a type of neuropathy many non-diabetic office and assembly line workers are familiar with: nerve damage related to movement or repetitive motion. The most common types are carpal tunnel syndrome (which affects the median nerve in the wrist) and tarsal tunnel syndrome (which affects the inside of the ankle). If you have diabetes, there's more of a chance that these tunnels will swell and "entrap" or squeeze the nerves inside.
Autonomic neuropathy. This type of neuropathy destroys the nerves that you can't directly control, including those in the stomach, bladder, intestinal tract, and genitals. Here are the most common forms of this neuropathy:
Gastroparesis is when you get nerve damage to the stomach. This condition can keep the stomach from emptying properly and cause unstable blood sugar. Symptoms of gastropareisis include nausea, bloating, vomiting, diarrhea, and constipation.
Bladder neuropathy occurs when you have nerve damage to the bladder. When the bladder loses nerves, it may feel empty even when it isn't. People with this type of neuropathy often don't empty the bladder completely, and the constant pool of urine can lead to frequent bladder infections.
Erectile dysfunction is what happens when there is nerve damage to the penis. If nerves in the penis become deadened, a man may have difficulty achieving or maintaining an erection.
How is diabetic neuropathy diagnosed?
Doctors usually suspect neuropathy whenever a patient with diabetes complains of symptoms such as pain, numbness, tingling, or frequent urinary tract infections. After getting a detailed description of the symptoms you're feeling, the physician will sometimes do a neurological evaluation -- a series of simple procedures that measure muscle strength, nerve function, and sensation -- that can confirm or rule out those suspicions. (Many times, however, the tests are not needed to make the diagnosis.) Neurological exams to test sensation and reflexes are done in the physician's office, if necessary.
In one common test, a doctor attaches a disk to the skin over a muscle. The disk releases small, usually painless electric shocks, and a needle measures how quickly the electricity moves along the nerves. In a patient with neuropathy, the impulse will be unusually slow.
In a similar test, known as an electromyogram (EMG), a doctor may insert a needle into the muscles to measure the electrical flow in deeper nerves. This test can determine whether the nerves are breaking down or healing. The doctor may also do a gastric emptying test to check for autonomic neuropathy.
What can I do to prevent neuropathy?
Tightly controlling your blood sugar with insulin and other diabetes medications, if necessary, is the best way to keep your nerve cells healthy. (Tight, or good, control is generally between 70 and 130 milligrams before meals and under 180 milligrams after eating, with a glycated hemoglobin under 7 percent.) However, you shouldn't try to achieve tight control on your own. The American Diabetes Association says that tight control can be hazardous for certain groups, including children, the elderly, people with end-stage kidney disease or severe vision loss, and diabetics with heart disease. Tight control can increase the risk of hypoglycemia, particularly in people with type 1 diabetes. So work closely with your doctor to determine what your blood sugar should be.
For those who can safely manage it, tight control can pay off. A seven-year study of more than 1,400 people with type 1 diabetes found that those who kept their blood sugar levels as close to the normal range as possible reduced their risk of nerve damage by 60 percent. Along with the medication, exercise and a fiber-rich, balanced diet can help you keep your blood glucose under control. Seeing your doctor regularly can also help: be sure to have a diabetes check-up at least once every three months.
According to the latest ADA guidelines, doctors should perform an annual test to assess urine albumin excretion in patients with type 1 diabetes who have had diabetes for at least 5 years and in all type 2 diabetic patients starting at diagnosis. The guidelines also recommend measuring serum creatinine at least annually in all adults with diabetes, regardless of the degree of urine albumin excretion.
How is neuropathy treated?
Once nerves have died, they can't be restored. But the right treatment can ease the symptoms of neuropathy and greatly improve a person's quality of life. The treatment, in fact, will be tailored to the type of neuropathy and complications you have:
If you're suffering from a burning pain or increased sensation, the doctor may treat you with a topical ointment called capsacin to relieve pain.
If you have a pins-and-needles sensation or shooting pain, your doctor may prescribe medicines approved specifically to help with this problem, such as antidepressants like duloxetine (Cymbalta) or anticonvulsants like pregabalin (Lyrica).
New guidelines that the American Diabetes Association released in 2017 urge physicians not to prescribe narcotics (opioids) as a first or even second-line treatment for diabetic nerve-related pain; as physician and study leader Rodica Pop-Busul, MD, PhD, explained, overprescription of opioids for neuropathy had resulted in addiction. Besides duloxetine and pregabalin, doctors could consider gabapentin or tricyclic antidepressants, the guidelines noted, but warned that the latter two carried the risk of more serious side effects and drug interactions.
If you're bothered by sudden spasms or cramping, a regime of stretching may help relieve your distress. Avoid high heels, cowboy boots, or other shoes that pinch your muscles. Taken for a couple of weeks, over-the counter medications such as acetaminophen (Tylenol) or ibuprofen (Motrin or Advil) may help ease the pain.
For gastroparesis, or nerve damage to the stomach, doctors frequently prescribe metoclopramide (Reglan), a drug that helps empty the stomach.
If you have bladder neuropathy, the drug bethanechol (Urecholine) can help clear urine from the bladder and prevent urinary tract infections.
If you're suffering from erectile dysfunction (ED), consult with your physician or a diabetes specialist. You may be prescribed an oral medication such as phosphodiesterase inhibitors like sildenafil (Viagra). Other possible options include vacuum erection devices and inflatable implants. (Diabetes Review also suggests that "no attempt should ever be made to treat ED without first consulting the significant other.")
If you have symptoms of Charcot foot, such as redness, swelling, and warmth, you should see a podiatrist or orthotist. He or she may immobilize your foot in a cast or splint while your foot heals. You may also need to protect the other foot with braces or crutches. In advanced cases, surgery may be necessary.
If you have an entrapment neuropathy, such as carpal tunnel syndrome, and pain, you may be treated with steroid injections (watch for temporarily increased blood sugars), braces, or surgery.
What else can I do to cope with neuropathy?
If you already have neuropathy, the following tips can help you manage the condition.
Avoid alcohol and cigarettes (especially the latter). They can worsen nerve damage.
Don't use electric blankets and heating pads on numb areas. You may burn yourself before you realize it.
For bladder neuropathy, try scheduling bathroom breaks every three or four hours even if you don't feel the need.
Take off your shoes and socks at every visit to the doctor and have him or her check your feet.
Protect your feet by wearing comfortable shoes that fit properly. Don't go barefoot, even around the house, and inspect your feet and toes daily for overlooked injuries. [See Diabetes and Foot Care for more suggestions.]
Take regular walks or do gentle stretching exercises such as yoga. This may help reduce discomfort for some types of neuropathy.
Regular stretching, a balanced diet with lots of fiber, and an exercise program that you and your physician develop will also help keep your blood sugar in check and help keep neuropathy from worsening.
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