FGF21 and familial dilated cardiomyopathy: In addition, the authors believe that running exercise induces a significant up‐regulation of cardiac klotho β (KLB) protein (the co‐receptor of FGF21), which makes cardiomyocytes susceptible to the effect of FGF21, and reverses diabetes‐induced myocardial mitochondrial dysfunction, oxidative stress and fibrosis by stimulating mitochondrial SIRT3, thereby preventing or slowing down the process of DCM (Jin et al., 2022).