Diabetes mellitus is a chronic disease with multiple metabolic defects that result in hyperglycemia arising from inadequate insulin activity. Type 2 diabetes has a genetic predisposition, but lifestyle, physical habits and age play important roles in determining its time of onset and severity. Type 2 diabetes is usually the result of a progression from reduced sensitivity of hepatic (liver) and peripheral-tissue cells to circulating insulin (ie, insulin resistance) to a progressive inability of the body to produce adequate insulin to overcome insulin resistance (ie, insulin deficiency due to beta-cell insufficiency) resulting in impaired glucose tolerance and ultimately overt diabetes. In the United States, an estimated 15.7 million people have diabetes, with type 2 diabetes occurring in approximately 90 to 95% of cases.