A positive relationship between circulating DPP-4 activity and the presence and degree of chronic hepatic conditions has been evidenced, including hepatitis C virus (HCV)-related hepatitis, nonalcoholic steatohepatitis (NASH), nonalcoholic fatty liver disease (NAFLD), and progression to cirrhosis; a positive correlation between liver biomarkers alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and DPP-4 activity has been observed in type 1 diabetes [72,73,74,75]. Here, GPT is linked to hepatitis A virus infection.