Fig. 2.

Mechanisms of action of antidiabetic drugs. The lifespan of type 2 diabetic patients is increasing steadily because of the availability of a wide range of antidiabetic drugs. These drugs decrease blood glucose levels by multiple mechanisms. Metformin, a widely used hypoglycemic drug, acts by increasing glucose utilization in the peripheral tissues and by reducing hepatic glucose output. Sulfonylureas stimulate insulin secretion from pancreatic β cells. The use of this class of drug is associated with hypoglycemic episodes. Thiazolidinediones (TZDs) improve the sensitivity of adipose tissue, skeletal muscles, and the liver towards insulin. Incretin therapies, such as DPP-4-resistant GLP-1 analogs and DPP-4 inhibitors that enhance endogenous GLP-1 levels, promote pancreatic release of insulin. In addition, they are reported to have insulin-independent actions in other tissues, including the brain. Recently introduced SGLT2 inhibitors increase glucose excretion in the urine by preventing glucose reabsorption in the renal tubules. Overall, these antidiabetic drugs have been shown to have beneficial actions in the brain either directly or indirectly through glycemic control