Diabetic neuropathy is nerve damage that occurs as the result of the high blood sugar seen in diabetes. Mononeuropathy is neuropathy that affects only a single nerve. Mononeuropathy can involve any nerve, but the third cranial nerve, which controls eye movement, is the nerve most often affected when other sources of nerve damage, such as entrapment, are not involved. Diabetic neuropathy usually causes sensory symptoms, involving pain, numbness and a "pins and needles" sensation," and it sometimes compromises motor function as well.
Controling Blood Sugar
There are a limited number of treatments available for any sort of diabetic neuropathy. What treatments exist are effective only against the sensory symptoms, the pain in particular. Very little can be done for motor dysfunction, which points to the central importance of keeping blood sugar under tight control to avoid further damage. Additional measures that will prevent further nerve damage include avoiding neurotoxins, such as alcohol, and avoiding deficiencies in vitamins B6 and B12 and folate, which are involved in nerve conduction. Some aspects of nerve function do improve when blood sugar is well controlled, although symptoms may not necessarily improve at the same time.
Improving Circulation
Multiple theories have been proposed to explain how high blood sugar leads to nerve damage, but the exact mechanism by which it occurs is still uncertain. However, poor circulation from diabetic damage to small blood vessels plays at least some role. In addition to controlling blood sugar, other measures that improve vascular health, such as controlling high cholesterol and blood pressure and not smoking, will help prevent the nerve damage that causes neuropathy. Most of the vascular damage from diabetes is irreversible, but it may still be possible to somewhat improve the circulation to nerves in patients with neuropathy. In a study reported in the March 13, 1999, issue of The Lancet, the high blood pressure drug trandolapril, an ACE inhibitor, was shown to improve some measures of nerve function in patients with diabetic neuropathy, although these changes were not accompanied by significant improvements in symptoms. ACE inhibitors are not routinely used to treat diabetic neuropathy, but current treatment guidelines do specify that all diabetics should be on an ACE inhibitor anyway to help prevent kidney damage.
Treatments For Neuropathic Pain
As of 2010, the only drugs approved for diabetic neuropathy treat the neuropathic pain. Gabapentin, sold under the trade name Neurontin, is an antiseizure medication that reduces nerve pain from a number of causes, including diabetes. Other drugs used for seizure control, such as carbamazepine, are sometimes used instead of or along with gabapentin in cases where gabapentin alone isn't working. Tricyclic antidepressants, such as amitriptyline and nortriptyline, also sometimes help with diabetic neuropathic pain, although they tend to have more side effects than the antiseizure drugs. None of these medications help with the motor symptoms of diabetic mononeuropathy, and they have limited benefit for sensory symptoms other than pain, such as numbness or "pins and needles."
References
- "Harrison's Principles of Internal Medicine," 16th edition; Dennis L. Kasper, et. al. ed.; 2005
- "Diabetes Care;" Diabetic Somatic Neuropathies; AJM Boulton, et. al.; June 2004
- "The Lancet;" Trandolapril and human diabetic neuropathy; Nicola Bell, et. al.; March 13, 1999
