HDAC4 and Hyperglycemia: Representative links include mTORC1-driven mislocalization of slit proteins and autophagy suppression [58,59], TXNIP coupling hyperglycemia to oxidative and EMT programs [13], EGFR–Rubicon autophagy blockade [123], ERK/VEGF activation in human DN podocytes [21], TGF-β/Notch-dependent EMT [121], ROCK and HDAC4 → calcineurin pro-apoptotic axes [84,93], complement-driven mitochondrial dysfunction [88], inflammasome/pyroptosis and TRAIL–DR5-mediated PANoptosis [55,92], and epigenetic/RNA control that rewires these hubs [57,70,137].