EASD 26: SARS-CoV-2 Associated With Reduced Risk of Type 1 Diabetes in Under-Thirties

09 Sep EASD 26: SARS-CoV-2 Associated With Reduced Risk of Type 1 Diabetes in Under-Thirties

Watch the Video presentation of this interview.

MedicalResearch.com: What is the background for this study?

Nolsøe and Nolsöe: New cases of type 1 diabetes (T1D) increased during the COVID-19 pandemic, but it was unclear whether this was due to SARS-CoV-2 infection. We aimed to examine whether the first infection with a SARS-CoV-2 variant during the pandemic was associated with subsequent new-onset type 1 diabetes. Infection was assessed by PCR between January 2020 and December 2021, during which the index, alpha, and delta viral variants were predominant. In this period the omicron variant had begun to spread worldwide but did not yet account for almost all SARS-CoV-2 infections. We assessed new cases of type 1 diabetes until December 2023. According to the National Institute of Diabetes and Digestive and Kidney Diseases, type 1 diabetes is an autoimmune condition in which the immune system attacks insulin-producing beta cells in the pancreas, and its relationship to viral triggers has been an active area of research for decades.

MedicalResearch.com: What are the main findings?

Nolsøe and Nolsöe: Our nationwide nested case-control study used Danish high-quality registries with a very high rate of test coverage by PCR, and we had complete information on vaccination status. We identified 2,115 individuals diagnosed with T1D before age 30 years in the period, and each case was matched 1:5 by age and sex to 10,575 diabetes-free controls. We found that SARS-CoV-2 infection was associated with a statistically significant 16% reduced risk of subsequent T1D across all variants combined across the whole four-year observation period. No individual viral variant alone showed a statistically significant association. Within the first 180 days of infection the risk was reduced by 42% compared to those without SARS-CoV-2 infection. However, we did not find a reduced risk in later time periods. The reduced risk was statistically significant among females, with a 26% reduced risk, but not among males. We did not find a difference in the risk of T1D following SARS-CoV-2 infection among those aged 0–10 and those aged 11–30 years.

MedicalResearch.com: Was the lowered risk linked to vaccination rates or number of vaccinations?

Nolsøe and Nolsöe: When we examined SARS-CoV-2 infection in relation to vaccination status we found that the reduced risk was confined to unvaccinated individuals who had had SARS-CoV-2 infection, with a 24% reduced risk compared to unvaccinated and uninfected individuals. However, the estimates among vaccinated individuals were imprecise with no evidence of interaction by vaccination status. We were unfortunately not able to investigate the lowered risk in relation to the number and types of SARS-CoV-2 vaccination due to a lack of statistical power.

MedicalResearch.com: Is there anything else you would like to add?

Nolsøe and Nolsöe: Our main findings indicate a potential protective effect of the first SARS-CoV-2 infection on the development of type 1 diabetes. Among many speculations, an explanation could be that certain viral infections can protect against or suppress autoimmune disease such as T1D. The study is observational in nature, which means we cannot definitively say that the reduced risk of type 1 diabetes was caused by SARS-CoV-2 infection, but we hope our study will motivate similar studies in other countries with high testing coverage and detailed high-quality data.

Disclosures: None disclosed.

Citation:
Nolsøe CV, Nolsöe RML et al. SARS-CoV-2 infection and subsequent risk of type 1 diabetes in individuals under 30: a nationwide nested case-control study. Presented at the European Association for the Study of Diabetes Annual Meeting (EASD 2026).

For a broader overview of how viral infections and immune responses relate to the development of type 1 diabetes and autoimmune conditions, see this MedicalResearch.com overview of type 1 diabetes and viral triggers — what the research shows.

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Last Updated on September 10, 2026 by Marie Benz MD FAAD