Diabetes is a chronic disease with multiple metabolic defects that result in hyperglycemia arising from inadequate insulin activity. Type 2 diabetes usually is the result of a progression from reduced sensitivity of hepatic and peripheral tissue cells to circulating insulin to a progressive inability of the body to produce adequate insulin to overcome insulin resistance, resulting in impaired glucose tolerance and ultimately overt diabetes. In the United States, an estimated 21 million people have diabetes, with type 2 diabetes occurring in approximately 90% to 95% of cases.