Three cases are reported of hypoglycemia manifested by profound sinus bradycardia and fatigue, which responded to i.v. dextrose with prompt normalization of the cardiac rhythm. The cases involved 3 different patients and disease processes: a young female who had anorexia nervosa and profound malnutrition; an elderly, nondiabetic male who subsequently experienced a transient ischemic attack: and a patient who had diabetes mellitus managed with chronic, subcutaneous insulin administration. It is vitally important that the emergency physician recognize unusual clinical manifestations of hypoglycemia and fully evaluate such scenarios when hypoglycemia may occur. Untreated, hypoglycemia may result in significant chronic morbidity, and rarely, in death. Bradyarrhythmias--particularly sinus bradycardia--should be added to the list of potential clinical manifestations of hypoglycemia.