Delayed-onset pulmonary edema complicating severe diabetic ketoacidosis was observed twice in one patient. Hemodynamic measurements during the second episode showed normal transmural pulmonary capillary wedge pressure, suggesting an alteration in alveolocapillary permeability. Hyperventilation and acidosis may underlie this alteration. Vigorous fluid therapy, while decreasing oncotic pressure, may also contribute to the pulmonary edema. The two episodes in one patient suggest that pulmonary microvascular diabetic angiopathy may predispose some diabetics with severe ketoacidosis to increased-permeability pulmonary edema.