COVID-19 Infection Linked to Increased Risk of Type 2 Diabetes

A large population-based study from the British Columbia Centre for Disease Control suggests that COVID-19 infection is associated with an increased risk of type 2 diabetes, particularly in unvaccinated and severely ill patients. The elevated risk can persist for up to three years after the initial infection.

Study Details and Findings

The research, published in Diabetes/Metabolism Research and Reviews, analyzed data from over 2 million adults in British Columbia who underwent COVID-19 testing between January 2020 and January 2024 [1]. The study included 296,390 individuals who tested positive for SARS-CoV-2 and 1.748 million who tested negative. Participants with pre-existing diabetes or residing in long-term care facilities were excluded from the analysis.

Over a median follow-up period of 874 days, 47,704 participants (2.3%) were diagnosed with type 2 diabetes. The incidence rate among those infected with COVID-19 was 11.6 cases per 1,000 person-years, compared to 9.3 cases per 1,000 person-years in those who tested negative, representing an 18% higher risk for those who had contracted the virus.

The highest risk was observed in the first year post-infection, but remained significantly elevated through years two and three. Beyond three years, the increased association became statistically insignificant.

Severity of Illness and Vaccination Status

The study revealed a strong correlation between the severity of the COVID-19 illness and the risk of developing type 2 diabetes. Compared to those who tested negative, individuals with COVID-19 who received ambulatory care had a 15% increased risk (HR, 1.15). Hospitalized patients experienced nearly double the risk (HR, 1.98), while those admitted to intensive care faced more than triple the risk (HR, 3.10) [1].

Notably, no increased risk of diabetes was observed among individuals who were fully or partially vaccinated. Unvaccinated individuals with COVID-19 had a 28% higher risk of developing type 2 diabetes (HR, 1.28) [1].

Implications and Future Research

Researchers emphasize that while the risks decrease over time, the burden of health loss remains significant, particularly among those who were hospitalized with COVID-19. These findings reinforce the growing body of evidence linking COVID-19 infection to an increased risk of type 2 diabetes.

The British Columbia COVID-19 Cohort was established as a public health surveillance system under the BC Centre for Disease Control [3]. This study builds upon previous research, offering a more detailed understanding of the long-term metabolic consequences of COVID-19 infection, accounting for vaccination status and illness severity.

Diabetes Canada encourages adults with type 1 or type 2 diabetes to receive the COVID-19 vaccine [4].