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Abstract
Principles: Previous studies have demonstrated that L-carnitine has important effects on the mitochondrial beta oxidation of long-chain fatty acids and glucose metabolism. In the present study, effects of the L-carnitine on lactic acid levels and glucose during the oral glucose tolerance test were investigated. Methods:
The blood was collected at the initial, first and second hours during the oral glucose tolerance test. The oral glucose tolerance test was repeated after oral carnitine therapy (3 gr/day) for seven days. According to the ADA criteria ten subjects (7 women / 3 men) had normal glucose tolerance (NGT) and eight subjects (4 women / 4 men) had impaired glucose tolerance (IGT).
Results: At the baseline, first hour and second hour plasma lactic acid levels showed difference between the NGT and IGT subjects before the carnitine therapy but this difference was not statistically significant. During the glucose loading, plasma lactic acid levels were increased at the first hour and returned to initial levels at the second hour in all subjects both before and after carnitine therapy. Carnitine therapy decreased the lactic acid levels in both groups in the all samples. In NGT group, there was significant decrease in lactic acid levels at the baseline and first hour; P< 0.05, <0.05. In IGT group, also, significant decrease in lactic acid levels at the first and second hour was observed; P<0.05, <0.05.
Conclusions : Effect of the carnitine on the lactic acid levels was higher in the subject with IGT than the NGT group at the baseline and first hour during the oral glucose tolerance test. Reduced plasma levels of lactic acid levels following L-carnitine treatment may be related with both improved insulin resistance
and increased oxidative glucose use by activating pyruvate dehydrogenase and decraesing intramithochondrial Acetyl CoA / CoA ratio.