Why Diabetes Raises Neuropathy Risk

Diabetic neuropathy is not bad luck. It builds up over years, and several of the things that drive it are within your control.

How common is it?

Nerve damage is one of the most common complications of diabetes. Medical reviews estimate that up to about half of people with diabetes develop some form of neuropathy over their lifetime. The most common type, distal symmetric polyneuropathy, starts in the toes and feet and can slowly move up the legs, and later the hands.

What high blood sugar does to nerves

Nerves are long, thin cells. The nerves that run to your toes are the longest in your body, which is why the feet are usually hit first. Years of high blood sugar damage them in two main ways:

• Direct damage to nerve cells. Extra glucose is pushed into chemical pathways that create harmful by-products and oxidative stress. Over time this injures the nerve fibers and their protective coating.
• Damage to the tiny blood vessels that feed the nerves. Nerves depend on very small blood vessels for oxygen and nutrients. Diabetes damages those vessels, so the nerves are slowly starved.

The smallest fibers, which carry pain and temperature, are often damaged first. That is why early symptoms can include burning or tingling, and why some people lose the ability to feel heat or a small cut.

Risk factors you cannot change

• How long you have had diabetes. Risk rises with every year.
• Age and height (taller people have longer nerves).
• Genetics. Some people develop neuropathy with relatively good control; others do not with worse control.

Risk factors you can control

• Blood sugar. In the landmark Diabetes Control and Complications Trial, people with type 1 diabetes who kept tighter glucose control cut their risk of clinical neuropathy by about 60 percent. In type 2 diabetes the benefit of glucose control alone is smaller, which is why the other factors below matter so much.
• Blood pressure. High blood pressure further damages the small vessels that feed nerves.
• Blood fats. High triglycerides and abnormal cholesterol are linked to neuropathy, especially in type 2 diabetes.
• Weight and activity. Excess weight and metabolic syndrome are independent risk factors. Regular physical activity improves blood sugar, blood pressure and circulation.
• Smoking. Smoking narrows blood vessels and is consistently linked to more nerve damage.
• Heavy alcohol use. Alcohol is toxic to nerves on its own and adds to the damage from diabetes.
• Vitamin B12. Long-term use of metformin, a very common diabetes medicine, can lower B12 levels, and B12 deficiency causes its own neuropathy. Diabetes guidelines recommend periodic B12 testing for people who take metformin. Do not stop any medicine on your own; ask your doctor about the test.

The bottom line

Neuropathy usually develops slowly, and the earlier it is found the more you can do to slow it and protect your feet. Ask your doctor for a foot and nerve check at least once a year, and work on the risk factors above. They also lower your risk of heart disease, kidney disease and eye disease.

Medical disclaimer: The information on this site is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always talk with your physician or other qualified healthcare provider about any medical condition or before starting any new treatment or supplement.