In fact, reductions in mitochondrial size and Mfn2 expression in skeletal muscle have been observed in both obesity and T2DM, and these reductions correlate with impaired insulin sensitivity (Hernández-Alvarez et al. 2010; Putti et al. 2015; Eshima 2021). This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.