Insulin action on glucose and protein metabolism during L-carnitine supplementation in maintenance haemodialysis patients

Background. Impaired protein anabolism and insulin resistance are characteristic features of maintenance haemodialysis patients. We have used a randomised, matched-paired, double-blind, placebo-controlled experimental design to determine the capability of intravenous L-carnitine supplementation to modify insulin resistance and protein catabolism in non-diabetic patients with end-stage renal disease (ESRD) undergoing chronic haemodialysis treatment. Methods. L-carnitine (20 mg(.)kg(-1)) (n = 9) or placebo (n = 10) were given intravenously at the end of seven consecutive dialysis sessions. Whole-body protein and glucose metabolism were assessed on interdialytic days by the L[1-C-13]leucine and the [2,2-H-2(2)]glucose kinetic models in the postabsorptive state and during euglicemic hyperinsulinemic clamp studies at baseline and at the end of the treatment period. Results. L-carnitine supplementation was associated with lower (P < 0.05) rates of leucine oxidation (-11 +/- 12%) and appearance from proteolysis (-6 +/- 2%) during the clamp studies than after placebo supplementation. The rates of glucose appearance in the postabsorptive state did not change significantly in the patients receiving L-carnitine treatment. Insulin-mediated glucose disappearance was improved by L-carnitine only in those patients (n = 5) (+18 +/- 3%, P < 0.05 vs placebo group, n = 5) with greater baseline insulin resistance, selected according to the median value of insulin sensitivity before treatment. Conclusions. L-carnitine supplementation was associated with protein-sparing effects in maintenance haemodialysis patients during hyperinsulinemia.