Hypoglycemic coma occurring 5 h after cardiac surgery in a nondiabetic adult patient was primarily triggered by: low cardiac output leading to severe hepatic functional derangement; metabolic acidosis, probably secondary to peripheral hypoperfusion; and possible inhibition of the adrenergic response due to anesthesia with fentanyl. Glucose infused at 8 g/h progressively increased the blood glucose level and paralleled hemodynamic improvement.