Impact of COVID-19 outbreak on the seasonality and incidence of type 1 diabetes mellitus: A nationwide cohort study

Abstract

BACKGROUND

Type 1 diabetes mellitus (T1DM) is an autoimmune disease with a multifactorial pathogenesis. Viral infections have been proposed as contributing triggers, supported by the disease’s seasonal pattern, which typically shows higher incidence in autumn and winter. The coronavirus disease 2019 (COVID-19) pandemic and associated lockdowns created a unique context to examine the incidence and seasonality of T1DM during a period characterized by reduced circulation of common viral infections.

AIM

To investigate the incidence and seasonality of T1DM before and during COVID-19 pandemic in relation to global viral infection rates.

METHODS

This population-based retrospective study utilized a nationwide computerized database. Extracted data included the number of new T1DM cases over the 8 years preceding and during the COVID-19 pandemic, demographic characteristics of affected individuals, and nationwide respiratory virus polymerase chain reaction data from weekly nasal wash sample collections.

RESULTS

A total of 2176 patients were diagnosed with new-onset T1DM during the pre-pandemic period, compared to 348 cases during the pandemic. In the same periods, 33727 respiratory virus-positive polymerase chain reaction results from nasal wash samples were recorded pre-pandemic, compared to 2603 during the pandemic. Additionally, 363399 positive COVID-19 cases were reported during the pandemic period. Seasonality analysis revealed a higher rate of new-onset T1DM cases and a weaker seasonal pattern during the pandemic. Trend analysis showed a consistent increase in T1DM incidence prior to COVID-19, with a more variable trend observed during the pandemic. Correlation analysis between T1DM incidence and respiratory viruses demonstrated a weak correlation between T1DM incidence and a few respiratory viruses.

CONCLUSION

The observed increase in new-onset T1DM cases and the disruption of its typical seasonal pattern during the COVID-19 pandemic suggest a potential association between respiratory virus exposure and the development of T1DM.

Keywords: Type 1 diabetes mellitus; COVID-19; Seasonality; Pathogenesis; Viral trigger

Core Tip: This population-based study assessed incidence and seasonality of type 1 diabetes mellitus (T1DM) before and during the coronavirus disease 2019 pandemic. A higher rate of new-onset T1DM and diminished seasonal pattern were observed during the pandemic, coinciding with reduced circulation of common respiratory viruses due to lockdown measures. These findings suggest respiratory viruses, including severe acute respiratory distress syndrome corona virus-2, may serve as environmental triggers for T1DM. Weak positive correlations were identified between T1DM incidence and respiratory viruses (e.g., respiratory syncytial virus, influenza). The results support a potential link between viral exposure and T1DM pathogenesis, highlighting the need for further research into underlying mechanisms and preventive strategies.