Hypoglycemia, a commonly encountered metabolic emergency, is most often easily diagnosed and rapidly treated with satisfactory patient outcome. If not recognized and treated promptly, hypoglycemia may cause irreversible central nervous system injury; it rarely results in death. The classic presentation of hypoglycemia, a patient with diabetes mellitus on medical therapy (Insulin or oral hypoglycemic agents) who presents with an altered sensorium, is frequently seen in the emergency department (ED). Less often, patients with this metabolic emergency present to the ED in a manner suggestive of a situation other than hypoglycemia. Patients may present with seizure activity or focal neurological deficits, leading the physician to treat a primary neurological syndrome and not immediately recognize the primary cause of the problem. Alternatively, patients with hypoglycemia will present to the ED with an altered mental status after a traumatic event. The physician may again assume that the alteration in consciousness has resulted from a head injury and not a metabolic disorder. Four cases are presented in which the medical history of the event (i.e., trauma) suggested head injury as an explanation of the presentation when, in fact, hypoglycemia was responsible for the altered sensorium. The diagnosis of hypoglycemia is easily made with the performance of a bedside screening test which can be subsequently confirmed by laboratory blood analysis. It is imperative that emergency physicians consider hypoglycemia in all patients with any mental status abnormality, focal neurological deficit, or seizure activity, even when the findings seem to be explained initially by other etiologies.