Irisin, interleukin-6/10/15 (IL-6, IL-10, IL-15), brain-derived neurotrophic factor (BDNF), fibroblast growth factors 2 and 21 (FGF2/21), leukemia inhibitory factor (LIF) and insulin-like growth factor 1 (IGF-1) and other myokines [5,7,8] have been proved to be able to resist chronic and inflammatory diseases, such as diabetes and tumor growth [9]. Here, FNDC5 is linked to diabetes mellitus.