Managing diabetes is essentially a balancing act, as patients and physicians work together to control blood glucose levels to avoid the symptoms of and long-term organ damage caused by glucose variability--the often unpredictable fluctuations between levels that are too high (hyperglycemia) and too low (hypoglycemia). For years, self-monitoring of blood glucose levels has been the treatment standard. With newer technology, however, continuous blood glucose monitoring (CGM) is now possible. This article describes CGM, presents evidence about its efficacy, and outlines how visual displays of CGM data can improve clinicians' decisions about therapies.