Many studies of tight control of blood glucose in critically ill patients are associated with poor outcomes. However, randomized studies of tight glucose control in patients admitted to coronary care or surgical intensive care units showed a reduction in mortality rates; supported by recommendations from professional organizations, many intensive care units implemented protocols for tight glucose control. More recent studies in medical intensive care units did not confirm the benefits of tight control, however, and the most recent study suggests that tight control increases mortality rates. Furthermore, tight control significantly increases episodes of hypoglycemia. The sum of the recent literature suggests that a degree of glucose control lies between the extremes of the adverse outcomes related to poor glucose control and those related to overly aggressive glucose control.