Altered C-Fiber Function as an Indicator of Early Peripheral Neuropathy in Individuals With Impaired Glucose Tolerance

OBJECTIVE - This study explored the importance of glycemic burden compared with features of the metabolic syndrome in the pathogenesis of diabetic neuropathy by comparing C-fiber function in People With type I diabetes to that in people with impaired glucose tolerance (IGT). RESEARCH DESIGN AND METHODS - The axon reflex-elicited flare areas (LDI-flares) were measured With a laser Doppler imager (LDI) in age-, height-, and BMI-matched groups, with IGT (n = 14) and type 1 diabetes (n = 16) and in healthy control subjects (n = 16). RESULTS - The flare area was reduced in the IGT group compared With the control (2.78 +/- 1.1 vs. 5.23 +/- 1.7 cm(2), p = 0.0001) and type 1 diabetic (5.16 +/- 2.3 cm(2), p = 0.002) groups, whereas the flare area was similar in the type 1 diabetic and control groups. CONCLUSIONS - This technique Suggests that small-fiber neuropathy is a feature of IGT. The absence of similar small-fiber neuropathy in those With longstanding type 1 diabetes suggests that glycemia may not be the major determinant of small-fiber neuropathy in IGT,