Diabetic Neuropathy
Diabetic Neuropathy
Dianna Quan, MD
emedicine
Neuropathies are characterized by a progressive loss of nerve fibers that can be assessed noninvasively by several tests of nerve function, including nerve conduction studies and electromyography, quantitative sensory testing, and autonomic function tests. A widely accepted definition of diabetic peripheral neuropathy is "the presence of symptoms and/or signs of peripheral nerve dysfunction in people with diabetes after exclusion of other causes."1 Diabetic neuropathy is classified into several syndromes, each with a distinct pattern of involvement of peripheral nerves. Patients often have multiple or overlapping syndromes.
Peripheral neuropathies have been described in patients with primary (types 1 and 2) and secondary diabetes of diverse causes, suggesting a common etiologic mechanism based on chronic hyperglycemia. The contribution of hyperglycemia has received strong support from the Diabetes Control and Complications Trial (DCCT).2 The dose-dependent effect of hyperglycemia on nerves has been supported further in recent years by increasing recognition of an association between impaired glucose tolerance (prediabetes) and peripheral neuropathy.3 Pathologically, numerous changes have been demonstrated in both myelinated and unmyelinated fibers.
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