Background Advances in paediatric type 1 diabetes management and increased use of diabetes technology have led to improvements in glycaemia, reduced risk of severe hypoglycaemia, and improved quality of life. Since 1993, progressively lower HbA1c targets have been set. The aim of this study was to perform a longitudinal analysis of HbA1c, treatment regimens, and acute complications between 2013 and 2022 using data from eight national and one international paediatric diabetes registries. Methods In this longitudinal analysis, we obtained data from the Australasian Diabetes Data Network, Czech National Childhood Diabetes Register, Danish Registry of Childhood and Adolescent Diabetes, Diabetes Prospective Follow-up Registry, Norwegian Childhood Diabetes Registry, England and Wales' National Paediatric Diabetes Audit, Swedish Childhood Diabetes Registry, T1D Exchange Quality Improvement Collaborative, and the SWEET initiative. All children (aged <= 18 years) with type 1 diabetes with a duration of longer than 3 months were included. Investigators compared data from 2013 to 2022; analyses performed on data were pre-defined and conducted separately by each respective registry. Data on demographics, HbA1c, treatment regimen, and event rates of diabetic ketoacidosis and severe hypoglycaemia were collected. ANOVA was performed to compare means between registries and years. Joinpoint regression analysis was used to study significant breakpoints in temporal trends. Findings In 2022, data were available for 109 494 children from the national registries and 35 590 from SWEET. Between 2013 and 2022, the aggregated mean HbA1c decreased from 8<middle dot>2% (95% CI 8<middle dot>1-8<middle dot>3%; 66<middle dot>5 mmol/mol [65<middle dot>2-67<middle dot>7]) to 7<middle dot>6% (7<middle dot>5-7<middle dot>7; 59<middle dot>4mmol/mol [58<middle dot>2-60<middle dot>5]), and the proportion of participants who had achieved HbA1c targets of less than 7% (<53 mmol/mol) increased from 19<middle dot>0% to 38<middle dot>8% (p<0<middle dot>0001). In 2013, the aggregate event rate of severe hypoglycaemia rate was 3<middle dot>0 events per 100 person-years (95% CI 2<middle dot>0-4<middle dot>9) compared with 1<middle dot>7 events per 100 person-years (1<middle dot>0-2<middle dot>7) in 2022. In 2013, the aggregate event rate of diabetic ketoacidosis was 3<middle dot>1 events per 100 person-years (95% CI 2<middle dot>0-4<middle dot>8) compared with 2<middle dot>2 events per 100 person-years (1<middle dot>4-3<middle dot>4) in 2022. The proportion of participants with insulin pump use increased from 42<middle dot>9% (95% CI 40<middle dot>4-45<middle dot>5) in 2013 to 60<middle dot>2% (95% CI 57<middle dot>9-62<middle dot>6) in 2022 (mean difference 17<middle dot>3% [13<middle dot>8-20<middle dot>7]; p<0<middle dot>0001), and the proportion of participants using continuous glucose monitoring (CGM) increased from 18<middle dot>7% (95% CI 9<middle dot>5-28<middle dot>0) in 2016 to 81<middle dot>7% (73<middle dot>0-90<middle dot>4) in 2022 (mean difference 63<middle dot>0% [50<middle dot>3-75<middle dot>7]; p<0<middle dot>0001). Interpretation Between 2013 and 2022, glycaemic outcomes have improved, parallel to increased use of diabetes technology. Many children had HbA1c higher than the International Society for Pediatric and Adolescent Diabetes (ISPAD) 2022 target. Reassuringly, despite targeting lower HbA1c, severe hypoglycaemia event rates are decreasing. Even for children with type 1 diabetes who have access to specialised diabetes care and diabetes technology, further advances in diabetes management are required to assist with achieving ISPAD glycaemic targets. Funding None. Copyright (c) 2024 Elsevier Ltd. All rights reserved, including those for text and data mining, AI training, and similar technologies.