The acute effects of glycemic control on axonal excitability in human diabetic nerves

Abstract

Objective: To investigate whether glycemic control is associated with reversible changes in axonal excitability in human diabetic nerves. It is known that voluntary contraction or compression ischemia alters nerve Na+/K+ pump activity, and axonal excitability changes due to the pump activity can be estimated by threshold tracking.

Methods: Threshold, the current required to produce a compound muscle action potential 50% of maximum, was determined from the stimulus-response curve, and threshold changes produced by maximal voluntary contraction or ischemia were measured before and after insulin treatment in 10 diabetic patients.

Results: Within 3 weeks of the start of treatment, the threshold changes became greater following voluntary contractions (+13+/-4% versus +23+/-5%; mean+/-SEM; p=0.04) and during ischemia (-5+/-2% versus -11+/-2%; p=0.04).

Conclusions: The extent of threshold fluctuation depends on multiple metabolic factors associated with diabetes such as decreased Na+/K+ ATPase activity, increased anaerobic glycolysis, and tissue acidosis, and nerve excitability can respond quickly to glycemic control in diabetic patients.