INS and type 2 diabetes mellitus: In 2014, Lindeboom et al. [68] utilized long-echo time 1H MRS to measure skeletal muscle acetylcarnitine concentrations and investigated the relationship between acetylcarnitine concentrations, insulin sensitivity, and mitochondrial function in different groups of individuals, including endurance-trained athletes, lean sedentary subjects, obese sedentary subjects, and patients with type 2 diabetes mellitus (T2DM).