The authors evaluated the effect of carnitine on glucose insulin metabolism. Twenty-five subjects free from metabolic disorders or serious functional alterations in the liver, kidneys or myocardium were studied. All were infused with a 5% glucose-enriched solution (Group A); 48 h later the same subjects were infused with a 5% glucose solution containing 2g carnitine (Group B). Variations in blood glucose and insulin levels and range were measured at different times during and after infusion. Study results showed that the administration of carnitine lead to an improvement in glucose metabolism, as demonstrated by a saving in insulin secretion accompanied, at least on a temporary basis, by a corresponding decrease in blood glucose which, however, remained within normal parameters.