Objective: The objective of this study was to assess the effects of continuous subcutaneous insulin infusion (CSII) therapy on glycaemic control and acute complications in children, adolescents, and young adults with type 1 diabetes mellitus (T1DM). Methods: The prospective observational study was done in patients on multiple daily injection (MDI) switching to pump system. All patients were followed at the Paediatric Diabetes Clinic at BIRDEM Hospital. They were trained on carbohydrates counting and started on continuous basal insulin infusion in addition to meal and high blood glucose correction insulin boluses. They were followed on insulin pump therapy for a 6-month period. Results: Twenty patients were analysed, from baseline to visit 2 after 6 months. The patients included in the study had T1DM for a mean duration of 4.7 ± 3.1 years. The age ranged from 3 to 25 years (mean 13.7 ± 6.1). There was 1% reduction in haemoglobin A1c (HbA1c) after 6 months, though it did not reach the statistical significance ( p = 0.084). There was significant reduction of mean fasting blood glucose level 13.4 ± 7.0 versus 6.9 ± 1.6 mmol/L ( p = 0.001), total insulin requirement ( p = 0.043), frequency of hypoglycaemic episodes ( p = 0.006), and diabetic ketoacidosis ( p = 0.002) events during CSII therapy. Conclusion: In our study, we found that switching young T1DM patients from MDI to insulin pump had been effective with achievement of a reduction in fasting blood glucose, HbA1c, and acute complications.