OBJECTIVE:: To review the findings and to discuss the implications of hyperglycemia in critically ill children. DESIGN:: A critical appraisal of an article with literature review. FINDINGS:: In this single-center, retrospective cohort study, the authors report that the prevalence of hyperglycemia ranged from 16.7% to 75%, depending on the cutoff values (120 mg/dL, 150 mg/dL, and 200 mg/dL), among nondiabetic children admitted to a pediatric intensive care unit. Hyperglycemia correlated with an increased in-hospital mortality rate (relative risk, 2.5; 95% confidence interval, 1.26-4.93 for maximum glucose within 24 hrs, >150 mg/dL; and relative risk, 5.68; 95% confidence interval, 1.38-23.47 for highest glucose within 10 days, >120 mg/dL), as well as a longer length of stay in the pediatric intensive care unit. This finding is in concordance with other adult and pediatric studies. However, without adjustment for severity of illness, the study does not distinguish cause and effect, nor does it address the role of strict glucose control in this group of patients. CONCLUSIONS:: This study adds to the growing body of knowledge that associates the timing, intensity, duration, and variability of glycemia with outcomes in critically ill children. However, its limitations restrict drawing causal relationships and prevents insights regarding therapy. ©2007The Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies.