SMAD3 and renal fibrosis: The overexpression of SIRT1, SIRT3, SIRT4, SIRT6, and SIRT7 has been found to improve abnormal manifestations in the progression of DN, such as inflammation, oxidative stress, renal fibrosis, as well as impaired cell apoptosis and autophagy, through multiple complex signaling pathways, including the SIRT1/NF-κB related pathway, TGF-β1/Smad3 pathway, and PI3K/AKT/FOXO pathway [7,10,16,61].