What are diabetic neuropathies?

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 neuropathies?

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 neuropathies?

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, include weight loss and depression

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