Diabetic neuropathies are nerve disorders that affect people with diabetes. They occur more often in people with persistently high blood sugar levels.
There are several different diabetic neuropathies. They include:
Peripheral neuropathy. This is the most common type. It affects the longest nerves in the body. These nerves are part of the peripheral nervous system. This is the network of nerves that carry signals from your brain and spinal cord to the rest of your body and back.
The most common symptoms of peripheral neuropathy are numbness or pain in the feet and lower legs.
Autonomic neuropathy. This neuropathy damages collections of nerves that control your unconscious body functions. It may affect your digestion, your circulation and your sexual function.
Localized nerve failures (focal neuropathy). A nerve that controls a single muscle can lose its function. For example, focal neuropathy may cause problems with eye movement that result in double vision. Or it may cause drooping of one cheek.
Diabetic neuropathies occur in both type 1 and type 2 diabetes. They are most common in people whose blood glucose (blood sugar) levels are not well controlled.
Diabetic neuropathies can occur in people who have had diabetes for a short time. But they are most likely to affect those who have had the disease for more than a decade. It is also more common in people older than 40. Diabetics who smoke are especially at risk.
Diabetic neuropathy results from several changes in the nerves. But the specific cause of neuropathy is not completely understood. A persistently high concentration of blood sugar surrounding nerve cells definitely plays a role. The nerve cells must adjust their internal sugar content to be in balance with their surroundings. To do so, nerve cells make and store the sugar sorbitol. Sorbitol can gradually damage nerve cells.
Damage to blood vessels also contributes to diabetic neuropathy. When blood vessels that feed nerve cells are damaged, the nerves may not get enough oxygen and nourishment.