Kronlage et al. showed that O-GlcNAcylation of HDAC4 alleviates HF in diabetes and found that O-GlcNAcylation of HDAC4 at serine (Ser)-642 is cardioprotective in DCM and inhibits Ca2+/calmodulin-dependent protein kinase II signaling (Kronlage et al., 2019). Here, HDAC4 is linked to diabetes mellitus.