Effect of an L-carnitine-containing peritoneal dialysate on insulin sensitivity in patients treated with CAPD: a 4-month, prospective, multicenter randomized trial

Background: In peritoneal dialysis, the high glucose load absorbed from dialysis fluid contributes to several metabolic abnormalities, including insulin resistance. We evaluate the efficacy of a peritoneal dialysis solution containing L-carnitine as an additive to improve insulin sensitivity. Study Design: Multicenter parallel randomized controlled trial. Setting & Participants: Nondiabetic uremic patients on continuous ambulatory peritoneal dialysis enrolled in 8 peritoneal dialysis centers. Intervention: Patients were randomly assigned to receive peritoneal dialysis diurnal exchanges with either a standard glucose-based solution (1.5% or 2.5% according to the patient’s need) or a glucose-based solution (identical glucose amount) enriched with L-carnitine (0.1%, weight/volume; 2 g/bag) for 4 months, the nocturnal exchange with icodextrin being unmodified. Outcomes & Measurements: The primary outcome was insulin sensitivity, measured by the magnitude of change from baseline in glucose infusion rate (in milligrams per kilogram of body weight per minute) during a euglycemic hyperinsulinemic clamp. Secondary outcomes were safety and tolerability, body fluid management, peritoneal dialysis efficiency parameters, and biochemistry tests. Results: 35 patients were randomly assigned, whereas 27 patients (standard solution, n12; experimental solution, n 15) were analyzed. Adverse events were not attributable to treatment. Glucose infusion rates in the L-carnitine–treated group increased from 3.8 2.0 (SD) mg/kg/min at baseline to 5.0 2.2 mg/kg/min at day 120 (P 0.03) compared with 4.8 2.4 mg/kg/min at baseline and 4.7 2.4 mg/kg/min at day 120 observed in the control group (P 0.8). The difference in glucose infusion rates between groups was 1.3 (95% CI, 0.0-2.6) mg/kg/min. In patients treated with L-carnitine– containing solution, urine volume did not change significantly (P 0.1) compared to a significant diuresis reduction found in the other group (P 0.02). For peritoneal function, no differences were observed during the observation period. Limitations: Small sample size. Conclusions: The use of L-carnitine in dialysis solutions may represent a new approach to improving insulin sensitivity in nondiabetic peritoneal dialysis patients.