GPT and type 2 diabetes mellitus: In addition to H2S, which is catalyzed by alanine aminotransferase (AST, also known as AAT), cysteine can be converted into another gaseous signaling molecule, endogenous sulfur dioxide (SO2), which inhibits the autophagic apoptosis of cardiomyocytes and improves myocardial fibrosis in rats with T2D through the PI3K/AKT pathway [135].