Tu172 - Association of COVID-19 and Development of Type 1 Diabetes - A Danish Nationwide Register Study

Bochra Zareini, MD PhD – Postdoc, Cardiology, Nordsjaellands Hospital; Kathrine Kold Sørensen, M.Sc. – PhD student, Section of Biostatistics, University of Copenhagen; Pia Eiken, MD PhD, – Associate professor, Consultant in Endocrinology, Endocrinology, Bispebjerg Hospital; Thea Fischer, MD PhD – Professor, Research, Nordsjaellands Hospital; Peter Lommer Kristensen, MD PhD – Associate professor, Consultant in Endocrinology, Endocrinology, Nordsjaellands Hospital; Maria Lendorf, MD PhD – Registrar in Oncology, Oncology, Nordsjaellands Hospital; Ulrik Pedersen-Bjergaard, MD DMsc – Professor, Endocrinology, Nordsjaellands Hospital; Christian Torp-Pedersen, MD DMsc – Professor, Cardiology, Nordsjaellands Hospital

Abstract Text: Aim
To investigate whether the incidence of type 1 diabetes (T1D) increased during the COVID-19 pandemic compared to previous years and if there is an association between SARS-CoV-2 infection and the development of T1D.
Methods
We used Danish nationwide registers to include all Danish residents < 30 years of age without diabetes from 2015-2021 and followed them from 01.01.2015 or their birth until 31.12.2021, development of T1D, age of 30, emigration, onset of cancer, initiation of immune modulating therapy, or development of type 2 diabetes or other autoimmune diseases. We calculated incidence rate ratios (A-IRR) of T1D adjusted for age and gender. Subsequently, we matched persons with COVID with three controls (1:3) on gender, birth year, and vaccination status and estimated relative rate differences.
Results
Of a total of 2,381,348 persons (median age 12.8 years (interquartile range (IQR): 3.4-21.1) and 51.4% males), 3,795 developed T1D. A-IRR with 95% confidence interval in each quarter of the year in 2020 and 2021 compared to 2019 was: Jan-Mar-2020: 1.12 [0.89; 1.12], Jan-Mar-2021: 1.10 [0.87; 1.10], Apr-Jun-2020: 1.10 [0.84; 1.10], Apr-Jun-2021: 1.55 [1.22; 1.55], Jul-Sep-2020: 1.16 [0.92; 1.16], Jul-Sep-2021: 1.24 [0.98; 1.24], Oct-Dec-2020: 1.02 [0.82; 1.02], Oct-Dec-2021: 1.06 [0.85; 1.06]. We matched 338,670 COVID-19 cases with 1,004,688 controls (median follow-up: 42 days (IQR: 11-225)). Among cases, 31 individuals developed T1D, compared to 110 individuals among controls (hazard ratio 0.87 (95% CI: 0.59-1.29)).
Conclusion
The increase in T1D incidence during Apr-Jun 2021 compared to Apr-Jun 2019 could not be attributed to the SARS-CoV-2 pandemic.