AIMS: Few studies have looked at nationwide data for insulin pump treatment. Since 1996 the Danish Childhood Diabetes Registry (DanDiabKids) has collected data on all Danish diabetic patients aged 0-15 yr. The purpose of this study is to evaluate the prevalence of continuous subcutaneous insulin infusion (CSII) use among Danish children with diabetes and to compare metabolic control in CSII-treated children and adolescents to those treated with MDI. MATERIALS AND METHODS: The Registry collects on a yearly basis data on insulin regimen, central measured hemoglobin A1c (HbA1c), and demographic data on all patients. In the period 2005-2011, 2983 young patients (1721 males) with diabetes were followed in the Registry. Mean observation period was 5.11 yr [standard error (SE) 0.09]. In the total period 1846 patients were treated with MDI and 1493 changed from MDI to CSII. In 2005, less than 5% of children were treated with CSII whereas the percentage of children on CSII increased to approximately 50% in 2011. The patients were divided into age groups, <5 yr, 5-10 yr, and > 15 yr. RESULTS: HbA1c was significantly higher in MDI-treated children, +5.29 (CI 95% 4.29; 6.29 mmol/mol). HbA1c in all age groups was significantly lower in CSII-treated patients, and longitudinally HbA1c continued to be lower in all age groups. In multivariate analysis, a low HbA1c at CSII start, centers with more than 100 pump patients, a more recent year of diabetes onset, a higher number of self-monitoring of blood glucose (SMBG) measurements, a higher number of daily boluses, and a higher percentage of bolus insulin were all related to a lower HbA1c. CONCLUSION: The percentage of children on pumps (CSII) is CSII treatment is associated with a significantly lower Hba1c, achieved just after treatment initiation. In the following years there is a parallel rise in HbA1c in both MDI as well as in MDI treated patients. Patients coming from larger clinics, and patients measuring more blood glucose values and taking more boluses have a better metabolic control.