Diabetic neuropathy is damage to nerves in the body that occurs due to high blood sugar levels from diabetes.
Nerve injuries are caused by decreased blood flow and high blood sugar levels. They are more likely to develop if blood sugar levels are not well controlled.
About half of people with diabetes will develop nerve damage. Most of the time symptoms do not begin until 10 to 20 years after diabetes has been diagnosed.
Nerve injuries may affect:
Nerves in the skull (cranial nerves)
Nerves from the spinal column and their branches
Nerves that help your body manage vital organs, such as the heart, bladder, stomach, and intestines (called autonomic neuropathy)
Symptoms often develop slowly over several years. They can vary depending on the nerves that are affected.
People with diabetes may have trouble digesting food. These problems can make your diabetes harder to control. Symptoms of this problem are:
Feeling full after eating only a small amount of food
Heartburn and bloating
Nausea, constipation, or diarrhea
Throwing up food you have eaten a few hours after a meal
Tingling or burning in the arms and legs may be an early sign of nerve damage. These feelings often start in your toes and feet. You may have deep pain, often in the feet and legs.
Nerve damage may cause you to lose feeling in your arms and legs. Because of this you may:
Not notice when you step on something sharp
Not know that you have a blister or small cut
Not notice when you touch something that is too hot or cold
Damage to nervves in your heart and blood vessels may cause you to:
Feel light-headed when you stand up (orthostatic hypotension)
Have a fast heart rate
Not notice angina, the chest pain that warns of heart disease and heart attack
Other symptoms of nerve damage are:
Sexual problems. Men may have problems with erections. Women may have trouble with vaginal dryness or orgasm.
Not being able to tell when your blood sugar gets too low
Bladder problems. You may leak urine and may not be able to tell when your bladder is full. Some people are not able to empty their bladder.
Sweating too much — when the temperature is cool, when you are at rest, or at other unusual times
Signs and tests
A physical exam may show:
A lack of reflexes in the ankle
A loss of feeling in the feet (your health care provider will check this with a brush-like instrument called a monofilament)
Changes in the skin
Drop in blood pressure when you stand up after sitting or lying down
Tests that may be done include:
Electromyogram (EMG) — a recording of electrical activity in muscles
Nerve conduction velocity tests (NCV) — a recording of the speed at which signals travel along nerves