L-CARNITINE ADMINISTRATION IMPROVES INSULIN SENSITIVITY IN PATIENTS WITH IMPAIRED GLUCOSE METABOLISM

Rationale: Insulin resistance and type II diabetes are characterized by hyperglycemia and hyperinsulinemia. Insulin resistance may be associated with mitochondrial dysfunction. L-carnitine, an intramitochondrial carrier of acylic groups, is a molecule involved in lipids and carbohydrates metabolism. Lcarnitine therefore may modulate cell energy metabolism. We designed a study to investigate the effects of oral L-carnitine administration on plasma glycemic and insulinemic profile in patients with impaired fasting glucose or diabetes mellitus type II. Methods: The effect of L-carnitine was investigated in 16 patients (12 males and 4 females); the mean age ± SD was 66.69±13.37 y. Patients were randomly assigned to two groups. The first group (LC, n=8; 5 M and 3 F) received L-carnitine (4 grams/day) and 1200 or 1400 Kcal/day standard diet for women or men respectively, for 10 consecutive days. The second group (C, n=8; 7 M and 1 F) received only 1200 or 1400 Kcal/day standard diet for women or men respectively, for 10 consecutive days. Oral glucose tolerance test (OGTT, basal and 2 hours), fasting plasma insulin levels and Homeostasis Model Assessment (HOMA-IR) were assessed in each group before and after treatment. Results: Fasting plasma glucose levels were not statistically different in the two groups after treatment. OGTT-2 hours significantly improved after treatment both in LC (232.62±64.75 mg/dl vs 146.25±59.04 mg/dl, p=0.015) and C group (193.25±64.11 mg/dl vs 128±53.29 mg/dl, p=0.04). Interestingly, we observed a significant improvement in plasma insulin levels and HOMA-IR after treatment in LC group (7.04±2.6 μU/ml vs 4.51±1.79 μU/ml, p=0.04; 1.95±0.79 vs 1.17±0.51, p=0.03). No significant differences in plasma insulin levels and HOMA-IR were observed in C group. Conlcusions: L-carnitine in association with low calorie diet significantly ameliorates OGTT-2 hours, reduces plasma insulin levels and diminishes insulin resistance, as indicated by HOMA-IR improvement.