Table 1.

Antidiabetic drugs that target proteins and their brain expressions.

	Pharmacological Effect	Target Protein	Brain Expression	Ref.
Insulin	Activates insulin receptor signaling	Insulin receptor	Yes	[21]
α-Glucosidase inhibitors	Suppress glucose absorption	α-Glucosidase	Yes	[22]
Sulfonylureas	Promote insulin secretion	Sulfonylurea receptor	Yes	[23]
Metformin	Improves insulin sensitivity, etc. *	AMPK, etc. *	Yes	[24,25,26,27]
Thiazolidinediones	Improve insulin sensitivity	PPARγ	Yes	[28]
DPP-4 inhibitors	Prevent GLP-1 breakdown	DPP-4	Yes	[29]
SGLT2 inhibitors	Promote glucose excretion	SGLT2	No	[30]
GLP-1 receptor agonists	Activate GLP-1 receptor signaling	GLP-1 receptor	Yes	[31]

*: The pharmacological effect and target proteins of metformin have not yet been completely identified.