GCG and type 2 diabetes mellitus: The clinical studies with vildagliptin in T2DM have shown that DPP-4 inhibition with vildagliptin attenuated the diminished sensitivity of the islets to glucose, reduced the insulin resistance due to inappropriate glucagon secretion and lipo-toxicity characterized by greater triacylglycerol storage in non-fat tissues, decreased the hyperglycemia that is associated with glucose toxicity, and maintained but did not restore the diminished maximum capacity of the β-cells to secrete insulin.