Objective: The German/Austrian Diabetes Patient Follow-up Registry (Diabetes-Patienten-Verlaufsdokumentation or DPV), England/Wales National Pediatric Diabetes Audit (NPDA), and Type 1 Diabetes Exchange (T1DX) in the United States investigated changes in hemoglobin A1c (HbA1c) and diabetes technology use from 2010 to 2018. Methods: Registry/audit data from 2010 to 2018 were analyzed in annual cohorts using linear regression for those <18 years of age with type 1 diabetes diagnosed at age >6 months. Time trends in HbA1c, pump, and continuous glucose monitoring (CGM) use were studied using repeated measurements linear and logistic regression models with an autoregressive covariance structure and with year and data source as independent variables. Results: A total of 1,172,980 visits among 114,264 (54,119 DPV, 43,550 NPDA, 16,595 T1DX) patients were identified. HbA1c remained clinically stable in DPV (7.7% [61 mmol/mol] to 7.6% [60 mmol/mol]), decreased in the NPDA (8.7% [72 mmol/mol] to 7.9% [63 mmol/mol]), and increased in T1DX (8.0% [64 mmol/mol] to 8.5% [69 mmol/mol] from 2010 to 2018). In all registries/audits, insulin pump and CGM use increased over time with greatest pump use in T1DX and lowest uptake reported in NPDA. Conclusions: These data reveal three different longitudinal patterns of change in registry/audit HbA1c from 2010 to 2018. Diabetes technology use increased throughout, at different rates. Quality improvement (QI) programs in DPV have been ongoing for 25 years, began in NPDA in 2009 and T1DX in 2016. We speculate that in England/Wales, development of networks, peer review, and implementation of QI measures contributed to reductions in population HbA1c. Many of these interventions had been implemented in DPV before 2010. Further efforts to understand this improvement, including the role of QI, and continued success within standardized documentation and benchmarking could inform T1DX programs to reduce HbA1c.