HDAC3 and type 2 diabetes mellitus: Moreover, studies have shown that specific inhibition of histone deacetylase 3 (HDAC3) can significantly improve the blood–brain barrier permeability and downregulate connexin expression in diabetic mice by targeting the Nrf2 signaling pathway and its downstream molecules, thus becoming a new target for the treatment of blood–brain barrier damage in T2DM [61].