PDP1 and type 2 diabetes mellitus: We have demonstrated that MRS coupled with hyperpolarized 13C-labeled pyruvate is capable of revealing the activity of critical enzymes involving energy homeostasis, as well as assessing the PDH and associated fluxes of interest in typical hepatic metabolic diseases such as type 2-diabetes, hepatic steatosis, cirrhosis, and nonalcoholic fatty liver disease.