A 54-year-old woman was admitted to our emergency department for acute confusion. She had only a history of chronic alcohol abuse with an abrupt withdrawal. The initial diagnosis was delirium tremens. Biological findings, however, showed a severe degree of metabolic acidosis (plasma pH 7.07, bicarbonate 9.6 mmol/l) with an increased anion gap (39.6 mmol/l). Serum glucose was normal and ketonuria was present. Ketoacidosis was also suspected and treated by fluid infusion and delivery of glucose with a favorable outcome. Differential ketoacidosis is discussed in the emergency room.