Background: The uptake of continuous subcutaneous insulin infusion (CSII) therapy in those with type 1 diabetes varies internationally and is mainly determined by the national healthcare reimbursement systems. The aim of this study is to estimate national and regional uptake of CSII therapy in children, adolescents and adults with type 1 diabetes in Ireland.Methods: A retrospective cross-sectional study was conducted utilizing the national pharmacy claims database in 2016. Individuals using CSII were identified by dispensing of infusion sets. The uptake of CSII was calculated as the percentage of people with type 1 diabetes claiming CSII sets in 2016, both in children and adolescent (age <18 years) and adult populations (≥18 years). Descriptive statistics including percentages with 95% confidence intervals (CIs) are presented, stratified by age-groups and geographical regions, and chi-square tests used for comparisons.Results: Of 20,081 people with type 1 diabetes, 2,111 (10.5%, 95% CI: 10.1%-10.9%) were using CSII in 2016. Uptake was five-fold higher in children and adolescents at 34.7% (95% CI: 32.9%-36.5%) than in adults at 6.8% (95% CI: 6.4%-7.2%). Significant geographical heterogeneity in CSII uptake was found, from 12.6% to 53.7% in children and adolescents (p<0.001), and 2% to 9.6% in adults (p<0.001).Conclusions: Uptake of CSII in people with type 1 diabetes is low in Ireland, particularly in those ≥18 years. Identification of barriers to uptake, particularly in this group, is required.