Caloric restriction and L-carnitine administration improves insulin sensitivity in patients with impaired glucose metabolism

JPEN J Parenter Enteral Nutr. 2010 May-Jun;34(3):295-9. doi: 10.1177/0148607109353440.


Background: Reduced circulating and tissue carnitine levels, possibly leading to impaired mitochondrial function, have been postulated to be involved in the pathogenesis of insulin resistance. However, whether L-carnitine administration may improve insulin sensitivity in patients with impaired fasting glucose (IFG) or type 2 diabetes mellitus (DM-2) is still controversial. The aim of the study was to explore the role of L-carnitine supplementation in influencing insulin sensitivity.

Methods: A randomized controlled study involving adult outpatients was designed. Adult patients referred to the outpatient clinic and within 10 days of the diagnosis of IFG or DM-2 were consecutively enrolled. Exclusion criteria were concomitant antidiabetic therapy and modifications of lifestyle during the previous 4 weeks. Patients were randomly assigned to receive a hypocaloric diet for 10 days (group C; n = 8) or the same dietetic regimen in addition to oral L-carnitine (2 g twice daily) supplementation (group LC; n = 8). Oral glucose tolerance test (OGTT), fasting plasma insulin levels, and homeostasis model assessment of insulin resistance (HOMA-IR) were assessed at the beginning and end of the study. Data were statistically analyzed using the Student t test for paired and unpaired data.

Results: OGTT at 2 hours improved in both groups. Only in the L-carnitine-supplemented group did plasma insulin levels and HOMA-IR significantly decrease when compared to baseline values.

Conclusions: Considering the role of caloric restriction in increasing the intestinal uptake of carnitine, the results suggest that oral L-carnitine administration, when associated with a hypocaloric feeding regimen, improves insulin resistance and may represent an adjunctive treatment for IFG and DM-2.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Blood Glucose / metabolism
  • Caloric Restriction*
  • Carnitine / pharmacology
  • Carnitine / therapeutic use*
  • Diabetes Mellitus, Type 2 / blood
  • Diabetes Mellitus, Type 2 / drug therapy
  • Female
  • Glucose Intolerance / blood
  • Glucose Intolerance / drug therapy
  • Glucose Metabolism Disorders / blood
  • Glucose Metabolism Disorders / drug therapy*
  • Glucose Tolerance Test
  • Humans
  • Insulin / blood*
  • Insulin Resistance*
  • Male
  • Middle Aged


  • Blood Glucose
  • Insulin
  • Carnitine