Reviewed by Deborah Wexler, MD
Diabetic neuropathy is a family of nerve disorders caused by diabetes. People with diabetes can, over time, develop nerve damage throughout the body. Neuropathies lead to numbness and sometimes pain and weakness in the hands, arms, feet, and legs. Problems may also occur in organ systems including the digestive tract, heart, and sex organs. People with diabetes can develop nerve problems at any time, but the longer a person has had diabetes, the greater the risk.
An estimated 50 percent of those with diabetes have some form of neuropathy, but not all with neuropathy have symptoms. The highest rates of neuropathy are among people who have had the disease for at least 25 years.
Diabetic neuropathy also appears to be more common in people who have had problems controlling their blood glucose levels, in those with high levels of blood fat and blood pressure, in overweight people, and in people over the age of 40. The most common type is peripheral neuropathy, also called distal symmetric neuropathy, which affects the arms and legs.
The causes are probably different for different varieties of diabetic neuropathy. Researchers are studying the effect of glucose on nerves to find out exactly how prolonged exposure to high glucose causes neuropathy.
Nerve damage is likely caused by a combination of factors:Metabolic factors, such as high blood glucose, long duration of diabetes, possibly low levels of insulin, and abnormal blood fat levels
Neurovascular factors, leading to damage to the blood vessels that carry oxygen and nutrients to the 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
Types of Diabetic Neuropathy
Diabetic neuropathies can be classified as peripheral, autonomic, proximal, or focal. Each affects different parts of the body in different ways:Peripheral neuropathy causes either pain or loss of feeling in the toes, feet, legs, hands, and arms.
Autonomic neuropathy causes changes in digestion, bowel and bladder function, sexual response, and perspiration. It can also affect the nerves that serve the heart and control blood pressure. Autonomic neuropathy can cause hypoglycemia (low blood sugar) unawareness, a condition in which people no longer experience the warning signs of hypoglycemia.
Proximal neuropathy causes pain in the thighs, hips, or buttocks and leads to weakness in the legs
Focal neuropathy results in the sudden weakness of one nerve, or a group of nerves, causing muscle weakness or pain. Any nerve in the body may be affected.