Center Size and Glycemic Control: An International Study With 504 Centers From Seven Countries

The variance in glycemic control between different childhood diabetes centers is not fully understood. Although the International Society for Pediatric and Adolescent Diabetes guidelines from 2014 recommended center sizes of more than 150 patients (1), it has not been thoroughly investigated whether glycemic control is associated with center size (2–4). We have data from more than 500 childhood diabetes centers from seven different countries and thereby a unique opportunity to elaborate further on this association. Therefore, this study aims to investigate the relationship between center size and glycemic control in children with type 1 diabetes (T1D). Patient data have been described previously (5). Briefly, the population comprised children with T1D in the age-group 3 months from seven high-income countries during 2013–2014: Austria, Denmark, England, Germany, Norway, Sweden, and Wales. Data were anonymized and obtained from five national registries/audits on children with T1D (Austria and Germany use the same electronic health record and England and Wales have a common National Paediatric Diabetes Audit, while Denmark, Norway, and Sweden have national registries). Mean HbA1c was compared between groups after adjusting for sex, age (<6 years, 6 to <12 years, and 12–18 years), duration of diabetes (<2 years, 2 to <5 years, and ≥5 years), and minority status (yes/no) (HbA1c adj) before and after stratifying for treatment modality (insulin injection/pump). Center size was defined as the number of patients with diabetes reported to be cared for in a center. Center size groupings were 1) <20, 2) 20 to <50, 3) 50 to <100, 4) 100 to <200, and 5) ≥200 patients. In total 54,494 children (48% females) with T1D across 504 centers in seven countries were included in the study. The number of centers per country varied between 14 (Wales) and 219 (Germany). Mean (SD) for age was 12.5 (3.9) years, mean age at T1D onset was 7.5 (4.0) years, and mean T1D duration was 5.0 (3.7) years. A total of 21% of patients had minority status, which varied between 5% (Wales) and 28% (Austria). A total of 38.1% of patients were on pump treatment, and the percentage varied between 25% (England) and 69% (Denmark). National coverage of T1D patients was >95% in all countries, apart from Austria, which had ∼80% data coverage. Included patients had 100% data coverage for all of the following variables: sex, age, diabetes duration, minority status, and HbA1c. Data on treatment modality were not available for 2,428 patients (4.5%); of these, 2,130 were from England and 154 were from Sweden. A total of 23.2% of centers had 200 patients, representing 12.3% of all centers. The distribution of small and large centers in the seven countries varied. England and Sweden had few small centers (34%). HbA1c adj was significantly higher in the centers with 50 patients, in both pen users (P 50 patients managed equally well; therefore, centralizing to very-high-volume diabetes centers may not necessarily be an advantage. Future research should focus on identifying reasons leading to differences in glycemic control in T1D patients cared for in small and large centers, e.g., the lack or presence of an updated multidisciplinary diabetes team