Good metabolic control prevents or at least postpones late vascular complications, but several studies indicate that such good metabolic control cannot be reached without simultaneous increase in the incidence of severe hypoglycaemia. We have been able to reduce late complications through multiple insulin therapy adjusted on the basis of active self control combined with active psychosocial support and education. A prospective regular registration of all hypoglycaemic incidents in about 130 diabetic children and adolescents shows that in spite of reasonably good HbA1c values (mean and median 6.9%, corresponding to 7.9% with the DCCT method), we have less incidence of severe hypoglycaemia (13-17 per 100 patient years) than reported in other recent studies (20-25 per 100 patient years). We saw no correlation between HbA1c and severe hypoglycaemia, but most hypoglycaemia was caused by mistake or reasons not related to degree of metabolic control. Our conclusion is that there is no inevitable relation-ship between low HbA1c and hypoglycaemia. Instead hypoglycaemia should be prevented parallel to and in the same way as we try to reach good metabolic control.