Effect of patient medication cost share on adherence and glycemic control.

INTRODUCTION Type 2 diabetes is a growing epidemic, with approximately 20.8 million persons with diagnosed and undiagnosed type 2 diabetes in the United States (National Institutes of Health 2007). Diabetes-related costs in the United States are staggering and result from mortality, permanent disability, and lost productivity (Hogan 2003). Improved glycemic management, as measured by reduced glycosylated hemoglobin (A1c), can minimize the risk of diabetes complications (UKPDS 1998), lower health care costs, and increase workplace productivity (Shetty 2005, Stephens 2006, Testa 1998, Tunceli 2007, Von 2005, Wagner 2001). Adherence to medications plays a critical role in the achievement and maintenance of glycemic control. Adherence to diabetes medication regimens has been associated with im-