Peripheral neuropathy is one of the many complications of long-standing diabetes. Usually neuropathy occurs about 8 to 10 years after the onset of diabetes. However, it is not uncommon to see patients presenting with neuropathic symptoms that have their diabetes diagnosed at that time or patients with 20 or more years of diabetes with little or no evidence of neuropathy. The symptoms of diabetic neuropathy consist of a slow and insidious numbness and tingling of the lower extremities that can progress to become a painful neuropathy. The pain is usually described as a burning sensation in the feet. Occasionally, the pain is described as a sensation of sharp, electric jolts traveling down the lower extremities. As it worsens, the pain acquires a deep bony nature. It tends to be worse at night commonly preventing or awakening the patients from sleep. As the neuropathy worsens, it affects the upper extremities and may involve the motor nerves with the complaint of weakness in the distal muscles of the legs and arms. The neuropathy of diabetes can also involve the autonomic nervous system causing problems with sweating, blood pressure, and sexual function.
Diabetic neuropathy is suspected when the patient's history and physical examination are compatible with the clinical picture in a setting of diabetes. In the absence of the history of diabetes, diagnostic tests to rule out diabetes is required. The workup is completed by the performance of an electromyogram with nerve conduction studies to quantitate the extent of involvement of the peripheral nervous system.
Diabetic neuropathy, unfortunately, has no effective treatment at this point. Adequate control of the patient's blood sugar, however, has been shown to slow the progression of the symptoms. Symptomatic treatment with various medications that suppress neuropathic pain, including Elavil, Tegretol and more recently Ultram, have been successful. Several experimental therapeutic trials are currently in progress, including a placebo-controlled trial of tramadol hydrochloride in painful diabetic neuropathy and a study on the therapeutic effect of aldose-reductase inhibitor, zopolrestat, in peripheral symmetric diabetic polyneuropathy.