Oral antidiabetics include several drug types. One type, called the sulfonylureas, stimulates insulin release from functioning beta cells in the pancreas and may either improve binding between insulin and insulin receptors or increase the number of insulin receptors. Second-generation sulfonylureas (glipizide and glyburide) are thought to be more potent than first-generation sulfonylureas. Other types include drugs that increase insulin receptor sensitivity (thiazolidinediones); drugs that delay or alter glucose absorption (acarbose, miglitol); drugs that increase the stimulus for insulin release (DPP-4 inhibitors, incretin mimetics); and insulin, which is used for replacement therapy.