GPT and metabolic dysfunction-associated steatotic liver disease: For example, ALT and AST are used as surrogate markers of NAFLD, and they also reflect hepatic expressions of MetS at an early stage11, 12; increased levels of ALT in liver are associated with vascular endothelial disorders and body insulin sensitivity, which are independent of obesity27; associations of elevated ALT and AST levels with MetS have also been reported28.