Three clinical phenomena have been defined in the last decade in patients with diabetes mellitus as a dangerous iatrogenic sequel of hypoglycemia. These are hypoglycemia unawareness, defective glucose counterregulation and a lowered hypoglycemic threshold for hypoglycemic symptoms. Former mild hypoglycemia episodes cause a decrease and a delay in the protective hormonal counterregulatory response and warning symptoms in subsequent episodes, and in the absence of these, risk of severe hypoglycemia increases considerably. It has been demonstrated that when protection is provided against hypoglycemia with strict monitoring programs designed to avoid even mild hypoglycemia episodes, blunted autonomic symptoms and counterregulatory hormonal responses are rectified. Therefore, the best course of action in the treatment of pediatric diabetes mellitus is frequent blood sugar measurements, flexible multiple dose insulin regimens facilitating insulin dose adjustments as required, and a diet. In order to implement this, it is essential to organize an intensive training program with the patient and family, and to provide psychological support and close coordination with the diabetes treatment team.