A 4-year-old girl was hospitalized in a local hospital with bloody diarrhoea, vomitus and abdominal pain. Because of acute abdominal symptoms she underwent appendectomy after which convulsions and acute respiratory distress were noticed. The child was transferred to the intensive care unit. During the examination she was unconscious, pale, oedematous with scattered ecchymoses, severe hypertension and urine output diminished to several ml per day. Routine blood tests showed microangiopathic anaemia, thrombocytopenia (52000/ul.) and uremia. Proteinuria and hematuria were revealed on urine examination. Among coagulation parameters kaolin-kefalin time (69 s) and D-dimers (2000-4000/ul.) were abnormal. On the strength of history, clinical and laboratory investigation the diagnosis of D-positive hemolytic uremic syndrome was established. Controlled artificial respiration (for 10 weeks), total parenteral alimentation (TPN), antihypertensive treatment and diuretics (furosemide, dopamine) were introduced. Daily temporary access hemodialyses were performed for 4 weeks. Subsequently peritoneal dialysis was started for 2 weeks. Despite the appropriate TPN glucose blood levels were unexpectedly high from first days from admission (200-330 mg%). Intensive intravenous insulin therapy was performed for 50 days. The child was discharged after 72 days with moderate renal function impairment (blood urea-53 mg%, creatinine-1,2 mg%), mild hypertension and proteinuria. Additional factor prone to thrombotic events was the 4G/4G genotype responsible for increased PAI-1 blood concentration, which may result in intensified fibrinolysis inhibition. Diabetes mellitus as a rare immunological complication of haemolytic uremic syndrome was suspected on the following evidence: positive anti-GAD antibodies (ELISA), elevated levels of glycosylated haemoglobin A1c, three-fold reduction of blood C-peptide concentration, negative family history for diabetes. After 12 y of follow up glucose and C-peptide concentrations were normal. Glucose loading test gave adequate response. Kidney function was decreased with serum creatinine 1.7-1.9 mg/dl and urea 60-75 mg/dl.