Exploring Variation in Glycemic Control Across and Within Eight High-Income Countries: A Cross-sectional Analysis of 64,666 Children and Adolescents With Type 1 Diabetes

OBJECTIVE International studies on childhood type 1 diabetes (T1D) have focused on whole-country mean HbA 1c levels, thereby concealing potential variations within countries. We aimed to explore the variations in HbA 1c across and within eight high-income countries to best inform international benchmarking and policy recommendations. RESEARCH DESIGN AND METHODS Data were collected between 2013 and 2014 from 64,666 children with T1D who were 1c levels that is attributable to between-center differences (intraclass correlation [ICC]). We also explored the association between within-center variation and children’s glycemic control. RESULTS Sweden had the lowest mean HbA 1c (59 mmol/mol [7.6%]) and together with Norway and Denmark showed the lowest between-center variations (ICC ≤ 4%). Germany and Austria had the next lowest mean HbA 1c (61–62 mmol/mol [7.7–7.8%]) but showed the largest center variations (ICC ∼15%). Centers in England, Wales, and the US showed low-to-moderate variation around high mean values. In pooled analysis, differences between counties remained significant after adjustment for children characteristics and center effects ( P value 1c levels (5.6 mmol/mol [0.5%] per 5 mmol/mol [0.5%] increase in center HbA 1c SD). CONCLUSIONS At similar average levels of HbA 1c , countries display different levels of center variation. The distribution of glycemic achievement within countries should be considered in developing informed policies that drive quality improvement.