OBJECTIVES: The objective of the study is to assess the cost of continuous subcutaneous insulin infusion ( CSII) application for children with diabetes type 1 in Sofia, Bulgaria and to compare the changes in BMI and HbA(1c), of  three groups of children- with  diabetes – applying insulin pens with human insulin, with  analog insulin and children with insulin pumps. METHODS: The study was performed from the point of view of the health insurance fund and patients. The data collected from the patients’ dossier including demographics about their age, sex, weight, duration of disease and HbA(1c) and type of treatment (CSII or analogue insulin treatment with a pen device). Cost of CSII, blood glucose monitoring system and strips was calculated. The primary outcome observed was the variation in HbA(1c) and the secondary was the BMI change. 51 children were observed. The data collected from the patients’ dossier including demographics about their age, sex, weight, duration of disease and HbA(1c) and type of treatment (CSII or analogue insulin treatment with a pen device). RESULTS:  The total yearly cost weighed with the duration of the disease is 1850 Euro (30% reimbursed). The average improvement of HbA (1c) after the CSII introduction is 1.72 and the average BMI was 37.03.  CONCLUSIONS: Improvements in glycemic control associated with CSII led to reduced HbA(1c) that can guarantee good diabetes management, but its control over BMI in growing children is still unclear. The insulin pumps have too many advantages: reduction in insulin requirements, reduced variability of insulin absorption, decreased hypoglycemia incidents, avoided pain, improved quality of life.