INS and type 2 diabetes mellitus: In db/db mice with T2DM, caffeic acid improved glucose metabolism by upregulating pancreatic insulin expression, enhancing hepatic glucokinase activity, inhibiting hepatic gluconeogenic G6Pase and phosphoenolpyruvate carboxykinase (PEPCK) activities, and increasing GLUT4 expression in the adipose tissue, leading to reductions in fasting blood glucose and HbA1c levels [86].