Hyperglycemia is a frequent complication in patients admitted to the hospital, and it is associated with increased morbidity, mortality and length of stay. The mechanisms that cause these complications are not clear, but multiple physiological processes are affected with increased glucose levels. Prospective studies have showed a positive impact of glucose control on morbidity, and mortality in different groups of patients. However, questions have risen regarding glucose targets, and consequently many healthcare providers do not have a well-formulated and objective approach to handle hyperglycemia in critically, and non-critically ill patients. In this article we review observational and prospective studies regarding hyperglycemia in the hospital. We also describe options for glucose control, and recommendations for the transition of glucose management to the ambulatory setting.