This article reviewed the relevant literature including published clinical trials and reviews on currently available oral hypoglycemic agents. Results showed that the benefits of glycemic control have been established through multiple clinical trials. Long-term control of blood glucose levels in type 1 and type 2 diabetic patients will decrease the incidence and prolong the time until progression of diabetic retinopathy, nephropathy, and neuropathy. Our increased understanding of the pathophysiology behind type 2 diabetes has led to the development of many new agents that are aimed at treating the underlying insulin resistance and relative insulinopenia. The sulfonylureas as a group have been used for many years and act by stimulating insulin secretion. They are useful alone or as combination therapy with insulin or another oral hypoglycemic agent. The biguanides act by decreasing hepatic glucose production and by increasing peripheral insulin sensitivity. The alpha-glucosidase inhibitors act nonsystemically by blocking the metabolism of digested polysaccharides and therefore lowering the amount of carbohydrate absorbed in a meal. Benzoic acid derivatives act in a manner similar to that of sulfonylureas by enhancing pancreatic insulin production. They offer a shorter duration of action, lowering the risk of hypoglycemia. The thiazolidinediones increase peripheral insulin sensitivity and are effective as both monotherapy and combination therapy. Oral hypoglycemic agents, when properly administered, are very effective in controlling type 2 diabetes and preventing long-term complications.