People with diabetes commonly develop temporary or permanent damage to nerve tissue. Nerve injuries are caused by decreased blood flow and high blood-sugar levels, and are more likely to develop if blood-glucose levels are poorly controlled. Some diabetics will not develop nerve damage, while others may develop this condition relatively early. On average, the onset of symptoms occurs 10 to 20 years after diabetes has been diagnosed. Approximately 50% of people with diabetes will eventually develop nerve damage.

Peripheral nerve injuries may affect cranial nerves or nerves from the spinal column and their branches. This type of neuropathy (nerve injury) tends to develop in stages. Early on, intermittent pain and tingling is noted in the extremities, particularly the feet. In later stages, the pain is more intense and constant. Finally, a painless neuropathy develops when pain sensation is lost to an area. This greatly increases the risk of severe tissue injury because pain no longer alerts the person to injury.

Autonomic neuropathies affect the nerves that regulate involuntary vital functions, including the heart muscle, smooth muscles and glands. Low blood pressure, diarrhea, constipation, sexual impotence, and other symptoms can be caused by autonomic neuropathies.