Your body is thick with nerves. The brain sends electrical messages through these wiry filaments of tissue, which snake down the spine before branching off in every direction. From fingertips to toes, nerves control everything from heartbeats to itches. This complex network is vital for health.

Unfortunately, diabetes can damage this crucial system. An estimated 60 to 70 percent of people with diabetes have neuropathy, a disease of the nerves. While diabetic neuropathy rarely hurts the nerves of the brain or spine, those in the rest of the body are fair game. (Some types of neuropathy, not discussed here, aren’t related to diabetes.) Here’s a look at the basics of neuropathy caused by diabetes.

Got the Nerve?
Just how diabetes can damage nerves remains largely the subject of scientific speculation, though researchers are eager to solve the puzzle in hopes of developing new therapies for a disease that is still a challenge to treat. Some suspect that abnormal proteins, which are abundant in diabetes because of high blood glucose, directly hurt the nerves. Or it may be that glucose itself interferes with chemical signaling or causes damage to the blood vessels that supply nerves with nourishment.

Whatever the reason, since nerves are responsible for so many different bodily functions, neuropathy can produce a wide range of symptoms. These tend to be mild at first and get worse over time. Sometimes neuropathy has no symptoms at all.

Three main types of neuropathy affect people with diabetes: peripheral, focal, and autonomic. Peripheral neuropathy is the most common type and can cause pain, tingling, weakness, or a loss of feeling in the legs, feet, toes, arms, hands, or fingers.

Focal neuropathy may come on rapidly and is caused by diabetes-related damage done to a particular nerve or group of nerves. For example, vision problems may be the result of damage to ocular nerves. Most focal neuropathies clear up over a period of months.

Autonomic neuropathy affects the system that controls body processes that don’t require conscious thought. It can cause problems with digestion, sexual function, and bladder control, though these issues can of course have other causes, too. One type of autonomic neuropathy is gastroparesis, which is caused by damage to the nerves that control how long food stays in the stomach before entering the small intestine. It affects 5 to 12 percent of people with diabetes.

Taking Control
Older people or those who’ve had diabetes for many years are in the most danger of developing neuropathy. Poor blood glucose control may also trigger the nerve disease, even among younger people or those who have had diabetes for only a short time. The best way to reduce your chances of getting neuropathy is by keeping blood glucose levels in check. A groundbreaking 1993 study, the Diabetes Control and Complications Trial (DCCT), found that tight control cut the risk of neuropathy by 60 percent. But even after nerves become damaged, improving blood glucose control may be able to relieve symptoms in many people. Exercise can help, too, although some workouts or sports may be dangerous for people with neuropathy.

The feet are a sore point for many people with diabetes, because neuropathy, along with poor circulation, tends to target them first. This is why annual foot exams are essential. The doctor may touch the feet with a thin nylon wire or a pin to look for hypersensitivity or numbness. Lack of sensation from neuropathy is a serious problem; it can lead foot wounds to go unnoticed and untended. If a deteriorating foot wound ulcerates and a resulting infection becomes unmanageable, amputation of the toe, foot, or even leg may be necessary. In 2004, the most recent year for which statistics are available, about 71,000 lower-limb amputations were performed in people with diabetes in the United States, not including those caused by injuries. Taking proper care of the feet, including frequent self-examinations and regular professional checkups coupled with good hygiene, can help prevent such a tragic outcome.

Other ways of diagnosing neuropathy include checking how a person senses temperature or vibration, measuring the nerves’ ability to send electrical signals, using ultrasound to observe the body’s inner workings, and running tests to detect abnormal changes in heart rate and blood pressure.

Combating neuropathy begins with trying to keep blood glucose levels in a healthy range. Beyond that, treatment depends on the type of neuropathy. For treating pain from peripheral neuropathy, the Food and Drug Administration has approved a few drugs, including duloxetine (Cymbalta, Yentreve) and pregabalin (Lyrica). Certain antidepressants, anticonvulsants, and, for severe cases, opioids may also be prescribed.

Meanwhile, researchers are racing to develop new medicines that work directly to prevent, stop, or even reverse nerve damage. Until better ways of treating neuropathy are found, vigilance—in blood glucose control, exercise, and foot care—will go a long way toward ensuring a happy nerve ending.