The issue of tight glucose control in intensive care remains controversial. Compelling evidence supports the use of intensive insulin therapy in postoperative patients, particularly those who have undergone cardiac surgery. In contrast, this strategy has been challenged in other situations, including medical, septic, post-traumatic and brain-injured critically ill patients, due to the lack of effect on mortality and to the increased risk of hypoglycemia. These data suggest that the optimal target for blood glucose needs to be better defined in critical care practice and might depend on the underlying pathology. Therefore, while awaiting the results of multi-centric studies, including a large heterogeneous cohort, a less aggressive approach for glucose control is preferable in the majority of critically ill patients.