Purpose: The aim of this study was to compare the general health-related quality of life (HRQoL), the metabolic control (HbA 1c ), the anthropometric measurement, and the cardiorespiratory fitness (expressed by VO 2max ) in youths with type 1 diabetes treated with continuous subcutaneous insulin infusion (CSII) to those receiving multiple daily injections (MDI). We looked for factors influencing the HRQoL and metabolic control. Methods: A total of 239 patients treated with CSII (51 girls and 53 boys) or MDI (64 girls and 71 boys) between ages 8 and 18 years were assessed with the Pediatric Quality of Life Inventory, Generic Core Scales, and Diabetes Module. VO2max was evaluated using the 20-meter shuttle run test. Results: CSII group had significantly better HRQoL according to both child self-report and parent proxy-report. Youths with CSII reported better physical, emotional, and school-related functioning, and had less diabetes-related fear and symptoms than the MDI group. There were no significant differences in body mass index z-scores, insulin doses, HbA 1c , and VO 2max between the groups. HRQoL was predicted by the CSII therapy (β =−0.220; p < .001) and the VO 2max (β = 0.386; p < .001), other clinical and anthropometric parameters had no effect; the HbA1c was predicted only by VO2max (β =−0.353; p < .001). Conclusions: Diabetic youths treated with CSII therapy have better HRQoL than those treated with MDI. There are no differences between the investigated groups in anthropometric data, glycated hemoglobin, and physical fitness. Moreover, good physical fitness has an important role in achieving better metabolic control and HRQoL, which underlines the importance of regular aerobic exercise in the treatment and care of type 1 diabetes in childhood.