Mean country A1C levels not tied to glycemic performance, study shows
UK researchers found that pediatric diabetes centers with greater glycemic variation across a country had higher A1C levels, suggesting that mean A1C levels within an entire country do not provide an accurate summary of the country's glycemic performance.
The findings in Diabetes Care, based on data on 64,666 children with type 1 diabetes across 528 pediatric diabetes centers in the US, Austria, Denmark, England, Germany, Norway, Sweden and Wales, revealed that Sweden had the lowest mean A1C and lowest variation among centers, while Austria and Germany had the largest center variations and next lowest A1C levels.
Variations in HbA1c across pediatric populations point to disparities in health care access
Studies of children with type 1 diabetes focusing on national mean HbA1c levels obscure variations within countries and provide inadequate measures of glycemic control, according to a study published in Diabetes Care.
This may result in a lack of informed policy-making regarding the health care system’s management of childhood diabetes, according to the researchers.
“Within-country studies have reported substantial differences in glycemic control across pediatric diabetes centers,” Dimitrios Charalampopoulos, PhD, MPhil, MSc, research associate at UCL Great Ormond Street Institute of Child Health at University College London, and colleagues wrote.
“Although some of these variations could be related to differences in patient case mix or preferences, some others may reflect differences in quality of, or access to, diabetes care. These unwarranted variations raise concerns about the equity of health care systems.”
In a cross-sectional study conducted from 2013 to 2014, researchers analyzed data from six large population registries of 64,666 children with type 1 diabetes across 528 pediatric diabetes centers in Germany, Austria, England, Wales, the United States, Sweden, Denmark and Norway. Researchers used fixed and random-effects models adjusted for age, sex, diabetes duration and minority status. Minority status was determined according to the patient’s or patient’s parents’ country of birth or the patient’s ethnicity.
Researchers estimated mean HbA1c level for each center and assessed the proportion of total variation in HbA1c between centers in each country. They then pooled all glycemic data to examine whether differences in mean HbA1c levels between countries continued after removing center effects and differences in the children’s risk profiles across countries.
The lowest mean HbA1c (7.6%) together with the lowest variation among centers was found in Sweden; Norway and Denmark also had the lowest between-center variations. The largest center variations (interclass correlation of approximately 15%) were found in Germany and Austria, which had the next lowest HbA1c levels (7.7% and 7.8%, respectively). Across all countries, centers with more variation in glycemic results also had higher HbA1c levels.
These findings suggest that whole-country mean HbA1c levels do not provide a fully accurate summary of the glycemic performance of a country, according to the researchers.
“The distribution of glycemic achievement across centers within countries should be considered, alongside national mean values, in developing informed policies that drive quality improvement,” they wrote.
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

Dimitrios Charalampopoulos, Julia M. Hermann, Jannet Svensson, Torild Skrivarhaug, David M. Maahs, Karin Akesson, Justin T. Warner, Reinhard W. Holl, Niels H. Birkebæk, Ann K. Drivvoll, Kellee M. Miller, Ann-Marie Svensson, Terence Stephenson, Sabine E. Hofer, Siri Fredheim, Siv J. Kummernes, Nicole Foster, Lena Hanberger, Rakesh Amin, Birgit Rami-Merhar, Anders Johansen, Knut Dahl-Jørgensen, Mark Clements and Ragnar Hanas


OBJECTIVE International studies on childhood type 1 diabetes (T1D) have focused on whole-country mean HbA1c levels, thereby concealing potential variations within countries. We aimed to explore the variations in HbA1c 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 <18 years of age across 528 centers in Germany, Austria, England, Wales, US, Sweden, Denmark, and Norway. We used fixed and random-effects models adjusted for age, sex, diabetes duration, and minority status to describe differences between center means and to calculate the proportion of total variation in HbA1c 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 HbA1c (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 HbA1c (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 <0.001). Across all countries, children attending centers with more variable glycemic results had higher HbA1c levels (5.6 mmol/mol [0.5%] per 5 mmol/mol [0.5%] increase in center HbA1c SD).

CONCLUSIONS At similar average levels of HbA1c, 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.

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