What does my nervous system do?
Nerves carry messages back and forth between the brain and other parts of the body. All of your nerves together make up the nervous system.

Some nerves tell the brain what is happening in the body. For example, when you step on a tack, the nerve in your foot tells the brain about the pain. Other nerves tell the body what to do. For example, nerves from the brain tell your stomach when it is time to move food into your intestines.
Image of nervous system showing its four main parts.
The nervous system has four main parts—cranial, central, peripheral, and autonomic. Diabetes can damage the peripheral, autonomic, and cranial nerves.

How can diabetes hurt my nervous system?
Having high blood glucose for many years can damage the blood vessels that bring oxygen to some nerves. High blood glucose can also hurt the covering on the nerves. Damaged nerves may stop sending messages. Or they may send messages too slowly or at the wrong times.

Diabetic neuropathy (ne-ROP-uh-thee) is the medical term for damage to the nervous system from diabetes.

How can diabetes damage to the peripheral nerves affect me?

o Peripheral nerves go to the arms, hands, legs, and feet. Damage to these nerves can make your arms, hands, legs, or feet feel numb. Also, you might not be able to feel pain, heat, or cold when you should. You may feel shooting pains or burning or tingling, like "pins and needles." These feelings are often worse at night. They can make it hard to sleep. Most of the time these feelings are on both sides of your body, like in both of your feet. But they can be on just one side.

Peripheral nerve damage can change the shape of your feet. Foot muscles get weak and the tendons in the foot get shorter. You can get special shoes that are made to fit softly around your sore feet or feet that have changed shape. These special shoes help protect your feet. Medicare and other health insurance programs may pay for special shoes. Talk to your doctor about how and where to get these shoes.

How can diabetes damage to the autonomic nerves affect me?
o Autonomic nerves help you know your blood glucose is low. Some people take diabetes medicines that can accidentally make their blood glucose too low. Damage to the autonomic nerves can make it hard for them to feel the symptoms of hypoglycemia (hy-po-gly-SEE-mee-uh), also called low blood glucose.

This kind of damage is more likely to happen if you have had diabetes for a long time. It can also happen if your blood glucose has been too low very often.

o Autonomic nerves go to the stomach, intestines, and other parts of the digestive system. Damage to these nerves can make food pass through the digestive system too slowly or too quickly. Nerve problems can cause nausea (feeling sick to your stomach), vomiting, constipation, or diarrhea.

Nerve damage to your stomach is called gastroparesis (gas-tro-puh-REE-sis). When nerves to the stomach are damaged, the muscles of the stomach do not work well and food may stay in the stomach too long. Gastroparesis makes it hard to keep blood glucose under control.

o Autonomic nerves go to the penis. Damage to these nerves can prevent a man's penis from getting firm when he wants to have sex. This condition is called erectile dysfunction or impotence (IM-po-tents). Many men who have had diabetes for many years experience it.

o Autonomic nerves go to the vagina. Damage to these nerves prevents a woman's vagina from getting wet when she wants to have sex. A woman might also have less feeling around her vagina.

o Autonomic nerves go to the heart. Damage to these nerves might make your heart beat faster or at different speeds.

o Autonomic nerves go to the bladder. Damage to these nerves can make it hard to know when you should go to the bathroom. The damage can also make it hard to feel when your bladder is empty. Both problems can cause you to hold urine for too long, which can lead to bladder infections. Another problem can be leaking drops of urine accidentally.

o Autonomic nerves go to the blood vessels that keep your blood pressure steady. Damage to these nerves makes your blood move too slowly to keep your blood pressure steady when you change position. When you go from lying down to standing up or when you exercise a lot, the sudden changes in blood pressure can make you dizzy.

How can diabetes damage to the cranial nerves affect me?
o Cranial nerves go to the eye muscles. Damage to these nerves usually happens in one eye, causing double vision. This problem happens all of a sudden and usually lasts for a short time.

o Cranial nerves go to the sides of the face. Damage to these nerves usually happens on only one side of the face. This nerve damage causes that side of the face to hang lower or sag. Usually the lower eyelid and lips sag. This problem is called Bell's palsy. It happens all of a sudden and tends to correct itself.

How do I know if I have nerve damage?
If you have one or more of the problems mentioned in this booklet, you may have some nerve damage from diabetes. Tell your doctor about the problem. Ask your doctor what you can do to make the problem better and to stop it from getting worse.