The incidence of type 1 diabetes (T1D) in children increased significantly during the COVID-19 pandemic (1,2). However, it is not known whether this increase is a persistent phenomenon, which would have significant implications for future patient care. The aim of this study was to investigate the long-term incidence of childhood T1D in Germany during the 9 years before and 4 years after the emergence of COVID-19.
We used data from the German Diabetes Prospective Follow-up (DPV) registry of children aged 6 months to 17 years newly diagnosed with T1D from 2011 to 2023. The coverage of the DPV registry for pediatric patients with incident T1D has been estimated at 93% (range 91–96%) for the period 2011–2020 (3). The analysis of anonymized data was approved by the ethics committee of the University of Ulm (314/2021; Ulm, Germany).
For the estimation of the year-specific crude incidence of diabetes (per 100,000 person-years [PY]), the number of new cases was related to the respective number of person-years at risk. Incidence estimates with 95% CIs for 2011–2023 were calculated assuming a Poisson distribution, standardized for age group (6 months to 4 years, 5–11 years, and 12–17 years) and sex.
Based on long-term prepandemic incidence trends from 2011 to 2019 assessed using multivariable negative-binomial regression, we estimated adjusted incidence rate ratios (IRRs) of observed versus predicted incidence with 95% CIs for 2020–2023 based on a Poisson regression model with a binary variable indicating observed and predicted data as independent variables.
For research groups interested in future collaboration, the aggregated data sets of this study can be requested from R.W.H. Because of patient protection and agreements with patients, data on the individual participant level cannot be shared with collaborators; however, remote data analysis is possible.
From 2011 to 2023, 37,784 children and adolescents with new-onset T1D were documented by German pediatric diabetes centers (Supplementary Table 1). For 2011–2019, the annual increase in the incidence of childhood T1D was 2.1% (95% CI 0.8–3.5%) (Fig. 1).
Incidence rates of T1D in children in Germany from 2011 to 2023. Incidences are given per 100,000 person-years (PY). Circles with vertical bars represent standardized estimates with 95% CIs; solid lines with bands represent standardized trend estimates with 95% CIs estimated from negative binomial trend regression models adjusting for age or sex.
Incidence rates of T1D in children in Germany from 2011 to 2023. Incidences are given per 100,000 person-years (PY). Circles with vertical bars represent standardized estimates with 95% CIs; solid lines with bands represent standardized trend estimates with 95% CIs estimated from negative binomial trend regression models adjusting for age or sex.
From the beginning of the COVID-19 pandemic, the observed incidence of childhood T1D was 25.1 (95% CI 24.2–26.1), 27.5 (26.6–28.6), 26.2 (25.3–27.2), and 21.0 (20.2–21.9) for the years 2020–2023, respectively (Fig. 1). The observed incidences from 2020 to 2022 were significantly higher than predicted (IRRs 1.14 [95% CI 1.08–1.19], 1.22 [1.16–1.28], and 1.14 [1.09–1.19], respectively; all P < 0.0001), but in 2023 lower than predicted (IRR 0.89 [0.85–0.94]; P < 0.0001) (Supplementary Table 2 and Supplementary Fig. 1).
This wave-like change in the incidence of T1D was related to age, with a greater and longer increase in younger age groups and a greater decline in the older age group (Supplementary Figs. 1 and 2). This resulted in a decrease in the peak of the age distribution at diagnosis of T1D from 11.7 years in 2011–2019 to 7.9 years in 2022. However, the age at diabetes diagnosis returned to prepandemic levels in the year 2023 (Supplementary Fig. 3).
This study found a significant and age-related, but temporary, increase in the incidence of T1D in children after the emergence of COVID-19 in Germany, showing a wave-like pattern, with incidence rates falling below estimates.
A population-based analysis from Scotland has shown that although there was a 20% rise in the incidence of T1D in children aged 6–14 years during the COVID-19 pandemic, particularly in 2021, the incidence dropped back to prepandemic levels by 2022 (4). With the extension of the observation period to the end of 2023, we can now show that the peak of the wave of T1D incidence was followed by a trough with lower incidence than expected. This suggests that the increased incidence of childhood T1D during the COVID-19 pandemic may have been the result of an accelerated transition from presymptomatic autoimmunity (stages 1 and 2) to clinically overt diabetes (stage 3). The temporary shift in the age at onset of diabetes to a younger age during the pandemic may also indicate a more rapid progression through the stages of diabetes.
The population-based data including more than 37,000 children with new-onset T1D during a 13-year-period constitute a strength of our study. The prepandemic annual increase in the incidence of childhood T1D found in our study was similar to that demonstrated in the U.S. between 2002 and 2018 (5). However, caution should be taken in overinterpreting the epidemiologic data presented here, because these changes should be placed in a longer-term context.
In summary, this study shows that there was a wave in the incidence of T1D in children after the emergence of COVID-19, with a peak followed by a trough pattern, possibly suggesting an acceleration of transition through diabetes stages from isolated autoimmunity to clinically overt diabetes.
This article contains supplementary material online at https://doi.org/10.2337/figshare.28204967.
Article Information
Acknowledgments. The authors thank A. Hungele and R. Ranz for support and development of the DPV documentation software (clinical data managers, Institute for Epidemiology and Medical Biometry, University of Ulm, Ulm, Germany). The authors also thank all centers participating in the DPV project (a list is available in the Supplementary Material).
Funding. This project is supported by the German Federal Ministry for Education and Research within the German Center for Diabetes Research (DZD; grants 82DZD14E1G and 82DZD02E3G). The DPV registry is supported by the German Federal Ministry for Education and Research within the DZD (grant 82DZD14E03), the Robert Koch Institute, and the German Diabetes Association.
The funders of this study had no role in study design, data collection, analysis, interpretation of data, writing of the manuscript, or decision to submit the paper for publication.
Duality of Interest. No potential conflicts of interest relevant to this article were reported.
Author Contributions. C.K. had the idea and conceptualized the study, interpreted the analyses, wrote the initial manuscript, and revised the manuscript. A.J.E. analyzed the data and designed the analyses, contributed to the interpretation of results, and reviewed and revised the manuscript. S.L., N.H., A.D., K.W., D.K., and K.G.-H. collected data, contributed intellectually to the research topics of the DPV initiative, and critically reviewed the scientific content of the manuscript. R.W.H. coordinated and supervised data collection, acquired funding for the study, and critically reviewed the manuscript for important intellectual content. J.R. conceptualized the study, analyzed the data, designed and supervised the statistical analysis, and critically reviewed and revised the manuscript. All authors approved the final manuscript as submitted and agreed to be accountable for all aspects of the work. A.J.E. and J.R. are the guarantors of this work and, as such, had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Handling Editors. The journal editors responsible for overseeing the review of the manuscript were Elizabeth Selvin and Naveed Sattar.
