Physicians and scientists are not sure what causes diabetic neuropathy. It is thought that several factors contribute to the disorder. High levels of glucose (blood sugar) contribute to chronic nerve damage. The extra sugar in the body appears to react chemically with the nerves or cells around the nerves. This reaction damages the nerves, causing poor transmission of signals and pain in most cases.

Studies also have shown that poor circulation or blood flow may contribute to neuropathy. High blood glucose (hyperglycemia) damages the blood vessels that carry oxygen and nutrients to the nerves. Without healthy blood flow, these nerves become damaged and die.

Other factors that may contribute to diabetic neuropathy include:

• Long duration of diabetes
• High fat (lipid) levels in the blood
• Mechanical injuries to nerves
• Genetics or inherited traits such as body type and cholesterol
• Smoking or use of alcohol

It is thought that there is no one cause for diabetic neuropathy. It is believed that a combination of factors present in patients with diabetes contributes to the development of the condition. Scientists are continuing to study glucose, protein and chemical reactions to more fully understand the causes of diabetic neuropathy.

Recent research into diabetic neuropathy includes these findings:

• U.S. and Japanese scientists have linked diabetic neuropathy to malfunctioning bone marrow cells that make insulin, a glucose-controlling hormone normally produced in the pancreas. They found that only those nerve cells that merged with the abnormal marrow cells had neuropathy.

• European researchers have found autoantibodies (self antibodies) linked to autonomic neuropathy in people with type 1 diabetes. The work suggests that neuropathy can in some cases be an autoimmune disorder, in which the body mistakenly attacks itself.

Scientists hope that such research into the origins of diabetic neuropathy could eventually lead to treatments.