INS and type 2 diabetes mellitus: In the present study, we evaluated the potential antidiabetic effect of KYNA administration via drinking water in spontaneously diabetic Goto-Kakizaki (GK) rats, The adult GK rat is a well-recognized model of type 2 diabetes, and it is characterized by impaired glucose-induced insulin secretion, decreased pancreatic beta cell mass, decreased insulin sensitivity in the liver, and moderate insulin resistance in skeletal muscles and adipose tissues [30,31].