Impaired glucose tolerance and neuropathy.
BACKGROUND
Peripheral neuropathy is common. Diabetes is the most common cause, accounting for approximately half of cases, but up to 1/3rd of neuropathy patients have no identifiable etiology. Among this population, impaired glucose tolerance (IGT or "prediabetes") is observed in approximately 40%. The exact nature of the relationship between IGT and neuropathy is debated.


RESULTS
A variety of evidence suggests IGT causes neuropathy. Neuropathy may occur early in diabetes. The neuropathy associated with IGT is clinically similar to early diabetic neuropathy, with preferential injury to small nerve fibers resulting in pain and autonomic dysfunction. IGT and diabetic neuropathy patients share abnormal microvascular endothelial dysfunction. Treatment of IGT subjects with diet and exercise reduces risk of progression to diabetes, and those with neuropathy experience a short-term improvement in small fiber function with sustained benefit for pain. An evolving literature links other aspects of the metabolic syndrome to peripheral neuropathy.


CONCLUSIONS
IGT is common in peripheral neuropathy patients. The extent to which IGT directly causes nerve injury as opposed to being a covariant with other equally or more important features (eg, obesity, metabolic syndrome) remains to be determined. Preliminary data suggest diet and exercise counseling may be a useful treatment strategy.
Smith
A Gordon
AG
Department of Neurology, University of Utah, Salt Lake City, Utah 84132, USA. gordon.smith@hsc.utah.edu
Singleton
J Robinson
JR
D003929:Diabetic Neuropathies / Q000378:metabolism* / Q000503:physiopathology*; D018450:Disease Progression; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D024821:Metabolic Syndrome / Q000150:complications / Q000378:metabolism / Q000503:physiopathology; D008833:Microcirculation / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D036421:Nerve Fibers, Unmyelinated / Q000378:metabolism / Q000473:pathology; D010525:Peripheral Nerves / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D010523:Peripheral Nervous System Diseases / Q000209:etiology / Q000378:metabolism* / Q000503:physiopathology*; D040242:Risk Reduction Behavior
D005947:Glucose