International comparison of glycaemic control in people with type 1 diabetes: an update and extension

Aims To update and extend a previous cross-sectional international comparison of glycaemic control in people with type 1 diabetes. Methods Data were obtained for 520,392 children and adults with type 1 diabetes from 17 population and five clinic-based data sources in countries or regions between 2016 and 2020. Median HbA(1c)(IQR) and proportions of individuals with HbA(1c) < 58 mmol/mol (<7.5%), 58-74 mmol/mol (7.5-8.9%) and >= 75 mmol/mol (>= 9.0%) were compared between populations for individuals aged <15, 15-24 and >= 25 years. Logistic regression was used to estimate the odds ratio (OR) of HbA(1c) < 58 mmol/mol (<7.5%) relative to >= 58 mmol/mol (>= 7.5%), stratified and adjusted for sex, age and data source. Where possible, changes in the proportion of individuals in each HbA(1c) category compared to previous estimates were calculated. Results Median HbA(1c) varied from 55 to 79 mmol/mol (7.2 to 9.4%) across data sources and age groups so a pooled estimate was deemed inappropriate. OR (95% CI) for HbA(1c)< 58 mmol/mol (<7.5%) were 0.91 (0.90-0.92) for women compared to men, 1.68 (1.65-1.71) for people aged <15 years and 0.81 (0.79-0.82) aged15-24 years compared to those aged >= 25 years. Differences between populations persisted after adjusting for sex, age and data source. In general, compared to our previous analysis, the proportion of people with an HbA(1c) < 58 mmol/l (<7.5%) increased and proportions of people with HbA(1c)>= 75 mmol/mol (>= 9.0%) decreased. Conclusions Glycaemic control of type 1 diabetes continues to vary substantially between age groups and data sources. While some improvement over time has been observed, glycaemic control remains sub-optimal for most people with Type 1 diabetes.