Diabetics develop diabetic neuropathy because of chronically high blood sugar levels that cause nerve damage, according to the Joslin Diabetes Center. Because neuropathy occurs in patients who do not have diabetes, doctors are not sure exactly how high blood sugar levels lead to this condition. One theory hypothesizes that an enzyme in the body transforms the excess sugar into sorbitol, which causes nerve cells to swell, resulting in neuropathy.
Another theory suggests that excess sugar in the blood triggers certain pathways in the body, resulting in nerve complications such as neuropathy, notes the Joslin Diabetes Center. Patients may suffer from different kinds of diabetic neuropathy, including sensory, autonomic and motor neuropathy, depending on which nerves in the body receive damage.
Additional factors put diabetic patients at risk of neuropathy, including poor lifestyle habits, inherited traits, previous nerve injury and autoimmune factors, notes the National Institute of Diabetes and Digestive and Kidney diseases. For example, some autoimmune diseases cause inflammation in the nerves, and certain genetic traits make patients more susceptible to nerve diseases. Neurovascular factors also contribute to diabetic neuropathy since certain neurovascular conditions cause damage to the blood vessels, which carry nutrients to the nerves. Other risk factors for diabetic neuropathy include older age and the duration a patient has diabetes. Patients who develop diabetic neuropathy are often overweight, have high levels of fat in the blood, and have high blood pressure.