Objectives: To evaluate the relationship between glucose derangement, insulin administration, and mortality among children on extracorporeal membrane oxygenation. Design: Retrospective cohort. Setting: Tertiary PICU. Patients: Two hundred nine children receiving extracorporeal membrane oxygenation, including 97 neonates. Interventions: None. Measurements and Main Results: Hyperglycemia and severe hyperglycemia were defined as a single blood glucose level greater than 15 mmol/L (270 mg/dL) and greater than 20 mmol/L (360 mg/dL), respectively. Hypoglycemia and severe hypoglycemia were defined as any single glucose level less than 3.3 mmol/L (60 mg/dL) and less than 2.2 mmol/L (40 mg/dL), respectively. A total of 15,912 glucose values were recorded. The median number of glucose values was 59 per patient, corresponding to a mean 0.53 ? 0.12 tests per hour. Sixty-nine patients (33.0 ) without dysglycemia and who received no insulin were defined as the control group. Eighty-nine (42.6 ) and 26 (12.4 ) patients developed hyperglycemia and severe hyperglycemia, respectively. Sixty-three (30.1 ) and 17 (8.1 ) patients developed hypoglycemia and severe hypoglycemia, respectively. Sixty-one patients (29.2 ) received IV insulin during extracorporeal membrane oxygenation. Both hyperglycemia and hypoglycemia were associated with increased mortality on extracorporeal membrane oxygenation (46 and 48 , respectively, vs 29 of controls; p = 0.03). However, after adjusting for severity of illness and extracorporeal membrane oxygenation complications, abnormal glucose levels were not independently related to mortality. Conclusions: Dysglycemia in children on extracorporeal membrane oxygenation was common but not independently associated with increased mortality. The optimal glucose range for this high-risk population requires further investigation.