Neuropathy is a serious consequence of diabetes. The best way to prevent it is to maintain control of your blood glucose levels. Research shows that tight blood glucose control decreases the risk of diabetic nerve damage by as much as 60%. Once you have neuropathy, however, tight glucose control will do little to cure your symptoms.
About 60–70% of people with diabetes develop neuropathy, although they may not notice any symptoms at first. Diabetes can cause three types of nerve damage: peripheral neuropathy, focal neuropathy, and autonomic neuropathy.
This is damage to the peripheral nerves, the nerves that connect your spinal cord to the rest of your body. It is the most common type, and it is a serious disorder that causes a slow, progressive loss of function in the sensory nerves in the arms and legs due to a lack of oxygen or nutrients, compression, and inflammation. Symptoms include numbness, tingling, and pain—most commonly in the legs, hands, and feet—but it can affect any part of the body. Symptoms range from mild to severe, depending on what nerves are affected, and may be worse at night.
Further nerve damage can lead to total loss of feeling in the affected areas. It can also lead to loss of reflexes and muscle control, loss of muscle tone and strength, foot ulcers and injuries to the feet that can become infected, loss of coordination and balance, and hair loss in the affected area.
This refers to a disruption of blood supply to a single nerve or nerve group. It leads to sudden pain or weakness in the area of the body served by the affected nerve. Focal neuropathy often improves gradually over two to six months without any treatment.
This type of neuropathy develops when diabetes damages the autonomic nervous system, which regulates body functions that are not under your voluntary control—for example, digestion, heart rate, and blood pressure. Symptoms of autonomic neuropathy include slow emptying of your stomach, poor bladder control, erectile dysfunction, rapid or irregular heartbeat, and abnormal sweating. Most individuals with autonomic neuropathy also have peripheral neuropathy.
Treatment of nerve damage
Improved control of blood glucose is the first step in treating neuropathy, but unfortunately it is rarely helpful. Thus, medication is usually needed. Amitriptyline, a medication also used to treat depression, is the most effective drug for relieving symptoms of peripheral neuropathy. The medication works by making more norepinephrine available to nerve cells. (Norepinephrine is a neurotransmitter, which is a chemical that carries messages between nerve cells.) Amitriptyline can cause drowsiness, urinary retention (an inability to empty the bladder completely), and a severe drop in blood pressure upon standing (orthostatic hypotension).
Starting with a small dose and then gradually increasing the dose can minimize these effects. Taking amitriptyline at bedtime also helps.
Desipramine (Norpramin) is another antidepression drug used to treat peripheral neuropathy. It has fewer side effects and is almost as effective as amitriptyline. When antidepressants are ineffective or cause too many side effects, your doctor may prescribe gabapentin (Neurontin). Neurontin, an anticonvulsant drug used for epilepsy, can be taken alone or in combination with amitriptyline. If side effects occur (typically, drowsiness and confusion), they usually can be minimized by lowering the dosage. A gabapentin-like drug called pregabalin (Lyrica) was recently approved for treating pain in people with diabetic neuropathy.
When autonomic neuropathy affects nerves in the digestive system, eating frequent, small, low-fat meals instead of three large meals a day can help prevent the nausea and vomiting caused by slowed emptying of the stomach. Treatment with metoclopramide (Reglan) or the antibiotic erythromycin can also improve stomach emptying. Diarrhea sometimes responds to antibiotics such as tetracycline (which counteract the overgrowth of intestinal bacteria that may contribute to diarrhea) or conventional antidiarrhea drugs.
Men with autonomic neuropathy may have damage to nerves that control erections. Poor blood glucose control appears to worsen the problem. In a recent study, men who had HbA1c levels over 8% had the greatest risk of severe erectile dysfunction.