OBJECTIVE To determine, in an unselected population of diabetic children and adolescents < 18 years of age, which HbA1c levels can be achieved, and to examine the relationships with insulin regimen, insulin dose, sex, diabetes duration, BM1, and frequency of home blood glucose monitoring (HBGM) and outpatient clinic attendance. RESEARCH DESIGN AND METHODS A total of 144 unselected subjects (73 boys and 71 girls) aged 11.8 ± 3.7 years (mean ± SD) were included in the study over a 6-month period. They had diabetes durations ranging from 5 months to 15 years (4.0 ± 3.0). They were followed by the same pediatric diabetologist and the same nurse. The yearly frequency of visits was 8.9 ± 2.0, and the monthly frequency of HBGM was 111 ± 27. Of the patients, 129 were treated with two daily insulin injections of an individualized mixture of rapid- and intermediate-acting insulins, and 15 adolescents were treated with four injections using the basal-bolus regimen. The patients were divided into two subgroups according to diabetes duration: ≤ 2 years (n = 53) and > 2 years (n = 91), i.e., outside the honeymoon period. HbA1c was measured by a high-pressure liquid chromatography method (normal values 3.9–5.5%). RESULTS The mean ± SD HbA1c level in the 144 children and adolescents was 6.6 ± 1.2% using our method. In 62% of the patients, it was possible to obtain an HbA1c level under the normal mean value plus 5 SD. HbA1c was not related to sex, number of insulin injections, or age, i.e., it was not poorer at adolescence. The mean daily insulin dose was 0.9 U/kg body wt, being lower during the first 2 years of diabetes and reaching 1 U at adolescence. HbA1c levels were lower during the first 2 years of diabetes (6.2 ± 1.0%) than afterwards (6.9 ± 1.2%), but the frequencies of outpatient visits and HBGM were higher. After 2 years, HbA1c was negatively correlated with the frequency of HBGM. The yearly incidence rate of severe hypoglycemic episodes was 0.2. After the age of 13 years, BM1 was significantly higher in girls and in adolescents on four daily injections. CONCLUSIONS In nearly two-thirds of diabetic children and adolescents, it is possible to obtain HbA1c levels under the normal mean plus 5 SD, which is considered satisfactory and close to that of the adult cohort of the Diabetes Control and Complications Trial (DCCT) with intensive treatment. There is no difference between the children on only two daily insulin injections and the adolescents on four injections. After 2 years of diabetes, increased frequency of HBGM helps reduce HbA1c levels, taking into account the “intensive” education of the patients and their families. Adolescent girls on four injections must pay attention to the risk of becoming overweight.