Aims/hypothesis <p>We investigated the association between continuous glucose monitoring (CGM) and acute and chronic diabetes-related complications and mortality risk in adults with type 1 diabetes.</p> Methods <p>This study included adults with type 1 diabetes who received intensive insulin therapy, based on data from the Korean National Health Insurance Service Cohort (2016–2022). The primary outcomes were diabetic ketoacidosis (DKA), severe hypoglycaemia (SH), end-stage kidney disease (ESKD), cardiovascular disease (CVD) and all-cause mortality. Between-group analyses (comparing outcomes between CGM users and non-users) were conducted using Cox proportional hazards regression models, and within-group analyses (comparing outcomes before and after CGM initiation) were performed using paired <i>t</i> tests.</p> Results <p>A total of 17,018 individuals (8509 CGM users and 8509 non-users) were included. CGM users had lower rates of DKA (adjusted hazard ratio [aHR] 0.40; 95% CI 0.33, 0.48), ESKD (aHR 0.43; 95% CI 0.32, 0.56), CVD (aHR 0.28; 95% CI 0.23, 0.33) and all-cause mortality (aHR 0.38; 95% CI 0.32, 0.46) than non-users. The aHR for SH was comparable between the two groups (aHR 0.92; 95% CI 0.77, 1.10 for users vs non-users). However, among CGM users, the mean frequency of SH decreased by 61.5% after CGM initiation (<i>p</i>&lt;0.001). The frequencies of DKA and CVD-related hospitalisation or emergency department visits also decreased by 60.0% and 50.0%, respectively (<i>p</i>&lt;0.001 for both).</p> Conclusions/interpretation <p>In this nationwide cohort study of adults with type 1 diabetes, CGM users had lower rates of both acute and chronic diabetes-related complications and all-cause mortality compared with non-users.</p> Graphical Abstract <p></p>