Trends in type 1 diabetes incidence between 2007 and 2023 and their association with SARS-CoV-2 infection in a population-based matched cohort study among individuals under 30 years old in Sweden
Authors' conclusion
Sweden, with its non-restrictive pandemic response, saw a transient increase in type 1 diabetes incidence that was only partially associated with SARS-CoV-2 infections. Other explanations should be investigated, including environmental and lifestyle factors.
Study context
- Population
- All individuals under 30 years old registered in Sweden, 2007–2023
- Exposure
- SARS-CoV-2 infection vs no infection; pandemic years (2020-2023) vs predicted pre-pandemic trend
- Outcome
- T1D incidence trends and risk of developing T1D after SARS-CoV-2 infection
Methodological detailsPoisson regression of deviation from pre-pandemic trends (2007-2019), Cox proportional hazards models, 5 controls per infected individual, matched by birth year, sex and region
- Poisson regression of deviation from pre-pandemic trends (2007-2019)
- Cox proportional hazards models
- 5 controls per infected individual, matched by birth year, sex and region
Main finding
As reported in the abstract
T1D incidence vs predicted linear trend; T1D after SARS-CoV-2 infection
Estimate (95% CI)
2021vs Predicted linear trendincidence increased by 12%
IRR 1.12(1.06–1.19)
2022vs Predicted linear trendincidence increased by 9%
IRR 1.09(1.02–1.16)
SARS-CoV-2 infectedvs Controlsoverall
aHR 0.96(0.79–1.16)
Observational data: associations, not effects.
Further findings
T1D after SARS-CoV-2 infection, children aged 5–10 years · within first 28 days after infection
- HR for developing T1D within first 28 days after infection, children 5–10 years
- 2.68 (95% CI 1.22, 5.89)
- Hazard over the whole follow-up period, children 5–10 years
- not increased
Original publication
Trends in type 1 diabetes incidence between 2007 and 2023 and their association with SARS-CoV-2 infection in a population-based matched cohort study among individuals under 30 years old in Sweden. Diabetologia. Published 18 September 2025. doi:10.
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