Carnitine supplementation improves metabolic flexibility and skeletal muscle acetylcarnitine formation in volunteers with impaired glucose tolerance: A randomised controlled trial eBioMedicine Muscle Specific Deletion of Carnitine Acetyltransferase Compromises Glucose Tolerance and Metabolic Flexibility ScienceDirect Frontiers The effects of L carnitine supplementation on glycemic markers in adults: A systematic review and dose response meta analysis There's a reason L carnitine keeps showing up in PCOS research Because PCOS is closely tied to insulin resistance, inflammation, and metabolic dysfunctionand L carnitine plays a role in energy metabolism and fat utilization.