Since 1995 there have been several new medications approved for the treatment of type 2 diabetes. The availability of these new medications has made the treatment regiment for type 2 diabetes complex. There are currently five classes of oral antidiabetic agents available in the United States. These classes include: sulfonylureas, meglitinides, alpha-glucosidase inhibitors, thiazolidinediones, and biguanides. Additionally there are several types of insulin and insulin analogs available for the treatment of hyperglycemia: regular, lispro, aspart, NPH, lente, ultralente, glargine, 70/30, 50/50, and 75/25. In this article, the mechanism, site of action, and adverse effects of these classes will be reviewed. The efficacy and important management issues of these glucose-lowering drugs used in monotherapy and in combination will be discussed.