Type 2 diabetes is a disorder that has numerous components, including insulin resistance, an insulin secretory defect, and an increase in hepatic glucose production. Until recently, only the insulin secretory defect could be treated. Within recent years, the thiazolidinedione (TZD) class of drugs, which targets primarily insulin resistance, was released. Originally developed in Japan as triglyceride-lowering agents, TZDs were found to be more effective in lowering blood glucose levels instead. The actions of 2 TZDs--rosiglitazone and pioglitazone--are discussed, and their glucose- and nonglucose-lowering effects are explained. Four case histories are presented to illustrate various patients' responses to TZDs in clinical practice. Although TZDs have been demonstrated to be effective in dealing with many different aspects of type 2 diabetes, further study, involving multiple clinical trials, is needed.