Carnitine increases glucose disposal in humans

Objective: The goal of this work is to assess the effect of L-carnitine on glucose disposal, particularly on insulin sensitivity, in healthy volunteer s. Methods: Fourteen healthy human volunteers were subjected to the intravenou s glucose tolerance test (analyzed by means of the minimal model technique) , together with indirect calorimetry and measurement of serum free fatty ac ids, after a bolus of glucose plus carnitine (C) or a bolus of glucose plus saline (P). Results: The minimal model demonstrated a significant increase in glucose d isposal from plasma with carnitine: Glucose effectiveness passed from 2.7%/ min to 3.8%/min. No significant changes were observed in the Insulin Sensit ivity Index or in Insulin/C-Peptide secretion. Calorimetry showed a signifi cant increase in respiratory quotient, resulting from a significant increas e in carbohydrate oxidation rate during carnitine administration by an aver age of 0.0176+/-0.0118 g/min (p=0.015). Energy expenditure was not modified by treatment. A smaller decrease in plasma fatty acid concentrations was n oted with carnitine plus glucose than after glucose alone. Conclusions: From these data it appears that carnitine stimulates glucose d isposal and oxidation in the healthy volunteer. Therefore, carnitine might be useful as an adjunct in the therapy of diabetes mellitus.