A 20-year old student had suffered since 3 years from diabetes mellitus type I, which was well-controlled by insulin-pump therapy. During a flight from Moscow to Los Angeles, the student all of a sudden had chest pain, dyspnea, and he vomitted repetitively--emergency landing at Zurich airport was necessary. The student presented at the emergency unit in a poor general condition with tachypnea (32/min) and tachycardia (136/min). Arterial blood gas analysis showed severe metabolic acidosis (pH 7.04), while pulmonary or cardiac disease could be ruled out. Diabetic ketoacidosis was caused by the pump running short of insulin. Treatment included rehydration and administration of insulin. Administration of insulin by an insulin-pump allows to continuously and flexibly adjust the dosage according to the requirement of the body. Interruption of insulin administration can cause, however, relatively fast ketoacidosis because exclusively short-acting insulin is used.