Effect of carnitine supplementation on energy utilization in patients with type 2 diabetes and long-term tube feeding: A CARE-compliant case report

Abstract

Introduction: Carnitine is essential for the energy utilization of long-chain fatty acids. However, the effects of carnitine supplementation on patients undergoing tube feeding remain unclear, and some enteral formula products do not contain carnitine. In order to gain insights into the role of carnitine supplementation on energy utilization in patients with long-term tube feeding, we observed the changes in respiratory quotient (RQ) of patients before and after the addition of carnitine due to the renewal of an enteral formula product. Case presentation: We observed 6 patients who continued tube feeding with the same enteral formula product scheduled for renewal. All 6 participants had diabetes, and indirect calorimetry data were available for 4 patients. Participants were observed for 3 months after switching to the new formulation. After the switching, a carnitine supplementation of 120 to 180 mg/day was provided, depending on the intake amount. One month after switching, blood free carnitine and total carnitine levels in all 6 patients increased from below the lower limit to within the range of the Japanese reference standard. In 3 of the 4 patients for whom indirect calorimetry was possible, the fasting RQ at baseline was >0.90, suggesting impaired lipid utilization. The mean fasting RQ significantly decreased 2 months after the switch. The 1- and 2-hour postprandial RQ also showed a significant decrease after switching. Conclusion: Carnitine supplementation of enteral formulas may be important for normal energy utilization of lipids in patients receiving long-term tube feeding. An evaluation using randomized controlled trials with a larger number of patients is required.