SIRT1 and diabetes mellitus: For instance, in diabetes, the level of SIRT1 (sirtuin 1) in cardiomyocytes decreases, causing increased phosphorylation of Ser473 on AKT, leading to increased dephosphorylation of Ser637 on DRP1, thereby enhancing DRP1 activity, which subsequently increases mitochondrial fission and aggravates cardiac ischemia-reperfusion injury (39).