GPT and fatty liver disease: In particular, when used together with linagliptin, a DPP4 inhibitor, APD668, may reduce liver steatosis, attenuate weight gain, and reduce alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels by inhibiting lipogenic-related gene (SREBP-1c, FASN and SCD-1) levels.