What are diabetic neuropathy?

 

Diabetic neuropathies are a family of nerve disorders caused by diabetes. People with diabetes can, over time, develop nerve damage throughout the body. Some people with nerve damage have no symptoms. Others may have symptoms such as pain, tingling, or numbness—loss of feeling—in the hands, arms, feet, and legs. Nerve problems can occur in every organ system, including the digestive tract, heart, and sex organs.

About 60 to 70 percent of people with diabetes have some form of neuropathy. People with diabetes can develop nerve problems at any time, but risk rises with age and longer duration of diabetes. The highest rates of neuropathy are among people who have had diabetes for at least 25 years. Diabetic neuropathies also appear to be more common in people who have problems controlling their blood glucose, also called blood sugar, as well as those with high levels of blood fat and blood pressure and those who are overweight.

 

What causes diabetic neuropathy?

 

The causes are probably different for different types of diabetic neuropathy. Researchers are studying how prolonged exposure to high blood glucose causes nerve damage. Nerve damage is likely due to a combination of factors:

• metabolic factors, such as high blood glucose, long duration of diabetes, abnormal blood fat levels, and possibly low levels of insulin
• neurovascular factors, leading to damage to the blood vessels that carry oxygen and nutrients to 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

 

What are the symptoms of diabetic neuropathy?

 

Symptoms depend on the type of neuropathy and which nerves are affected. Some people with nerve damage have no symptoms at all. For others, the first symptom is often numbness, tingling, or pain in the feet. Symptoms are often minor at first, and because most nerve damage occurs over several years, mild cases may go unnoticed for a long time. Symptoms can involve the sensory, motor, and autonomic—or involuntary—nervous systems. In some people, mainly those with focal neuropathy, the onset of pain may be sudden and severe.

Symptoms of nerve damage 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 blood pressure after standing or sitting up
• problems with urination
• erectile dysfunction in men or vaginal dryness in women
• weakness

Symptoms that are not due to neuropathy, but often accompany it, including weight loss and depression.

 

Can diabetic neuropathy be prevented?

 

The best way to prevent neuropathy is to keep blood glucose levels as close to the normal range as possible. Maintaining safe blood glucose levels protects nerves throughout the body.

 

How are diabetic neuropathy diagnosed?

 

Doctors diagnose neuropathy on the basis of symptoms and a physical exam. During the exam, the doctor may check blood pressure, heart rate, muscle strength, reflexes, and sensitivity to position changes, vibration, temperature, or light touch.

 

Foot Exams

 

Experts recommend that people with diabetes have a comprehensive foot exam each year to check for peripheral neuropathy. People diagnosed with peripheral neuropathy need more frequent foot exams. A comprehensive foot exam assesses the skin, muscles, bones, circulation, and sensation of the feet. The doctor may assess protective sensation or feeling in the feet by touching them with a nylon monofilament—similar to a bristle on a hairbrush—attached to a wand or by pricking them with a pin. People who cannot sense pressure from a pinprick or monofilament have lost protective sensation and are at risk for developing foot sores that may not heal properly. The doctor may also check temperature perception or use a tuning fork, which is more sensitive than touch pressure, to assess vibration perception.

 

Other Tests

 

The doctor may perform other tests as part of the diagnosis.

• Nerve conduction studies or electromyography are sometimes used to help determine the type and extent of nerve damage. Nerve conduction studies check the transmission of electrical current through a nerve. Electromyography shows how well muscles respond to electrical signals transmitted by nearby nerves. These tests are rarely needed to diagnose neuropathy.
• 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 be used to assess the structure of these organs and show whether the bladder empties completely after urination.

 

How are diabetic neuropathy treated?

 

The first treatment step is to bring blood glucose levels within the normal range to help prevent further nerve damage. Blood glucose monitoring, meal planning, physical activity, and diabetes medicines or insulin will help control blood glucose levels. Symptoms may get worse when blood glucose is first brought under control, but over time, maintaining lower blood glucose levels helps lessen symptoms. Good blood glucose control may also help prevent or delay the onset of further problems. As scientists learn more about the underlying causes of neuropathy, new treatments may become available to help slow, prevent, or even reverse nerve damage.