Canadian researchers have found that people infected with Covid-19 were significantly more likely to be diagnosed with type 2 diabetes within a year after infection, compared with those who had not been exposed to the virus, with men having a greater chance than women of developing the diabetes.
The study also found that people ill enough to be admitted to hospital had more than double the risk of a diabetes diagnosis, compared with those who were not infected, while those admitted to the ICU were more than three times as likely to develop diabetes.
The findings add to a growing body of evidence about Covid’s long-term effects, reports The New York Times.
“This is definitely a concern in terms of long-term outcomes,” said Dr Naveed Janjua, the paper’s senior author and a professor at the School of Population and Public Health at the University of British Columbia.
“With a respiratory infection, you usually think, ‘seven or eight days and that’s it’,” he added. “Here we’re seeing lingering, lifelong effects.”
The study, published in JAMA Network Open, used a large data set from British Columbia to compare diabetes diagnoses among more than 125 000 individuals who had tested positive for Covid in 2020 and 2021 with those of more than 500 000 unexposed people during the same period.
Although Covid vaccines became available in December 2020, most participants in both the exposed and unexposed groups had not been fully vaccinated.
More than a dozen studies have examined the link between Covid and diabetes, with most reporting an increase in diagnosis after infection, as well as higher risks for men and those with severe disease.
The findings do not prove the infection causes diabetes, however. Experts said it was possible, for instance, that patients recovering from Covid were more likely to be diagnosed with diabetes simply because they were receiving more regular care.
Still, there are plausible biological explanations for a link between the two conditions, said Dr Pamela Davis, a professor of medicine at Case Western Reserve University in Cleveland, who co-wrote a commentary accompanying the study.
“It’s reasonable to ask, ‘Is this an actual increase, or just something that accelerated diabetes that was coming anyway in people, but they got it earlier?’” Davis said.
“But even if it’s just an acceleration, this will be costly,” she added. “The human suffering, the risk of complications in the eyes, the blood vessels, the heart, the kidneys, the days of productivity and work lost – all of those things will be accelerated. I’m worried about this.”
The coronavirus infects beta cells in the pancreas that make insulin, Davis said, and cause cell death. These cells are dotted with the ACE2 receptors that the virus uses as an entry path.
“If you put the beta cells of the pancreas in a culture dish, the virus will avidly infect these cells and destroy them,” she said.
Stress also plays a role in the development of diabetes, and the inflammatory response that accompanies Covid has been linked to the destruction of beta cells. People with severe Covid may also produce antibodies that attack their body.
Other viral infections have also been associated with the development of diabetes, said Janjua, whose research before the pandemic focused on hepatitis.
“With hepatitis C, we have strong evidence the infection is linked to an increased risk of diabetes as well as cardiovascular outcomes and many other systemic outcomes outside the liver as well,” Janjua said.
The new study found that adults who had tested positive for the virus were 17% more likely to develop diabetes within a year of the positive test. Men were 22% more likely to develop diabetes, compared with unexposed individuals. The elevated risk for women was not statistically significant overall unless they were hospitalised or admitted to an ICU.
The researchers matched infected and unexposed people by age and sex, and made adjustments to account for differences in underlying health conditions, socioeconomic status, vaccination status and other factors.
They calculated that of all new cases of diabetes, some 3.4% could be attributed to a Covid infection. For men, 4.75% of new cases were attributed to Covid.
Study details
Association of COVID-19 Infection with Incident Diabetes
Zaeema Naveed, Héctor Velásque García, Stanley Wong, James Wilton, Geoffrey McKee, Bushra Mahmood, Mawuena Binka, Drona Rasali, Naveed Janjua.
Published in JAMA Network Open on 18 April 2023
Abstract
Importance
SARS-CoV-2 infection may lead to acute and chronic sequelae. Emerging evidence suggests a higher risk of diabetes after infection, but population-based evidence is still sparse.
Objective
To evaluate the association between COVID-19 infection, including severity of infection, and risk of diabetes.
Design, Setting, and Participants
This population-based cohort study was conducted in British Columbia, Canada, from January 1, 2020, to December 31, 2021, using the British Columbia COVID-19 Cohort, a surveillance platform that integrates COVID-19 data with population-based registries and administrative data sets. Individuals tested for SARS-CoV-2 by real-time reverse transcription-polymerase chain reaction (RT-PCR) were included. Those who tested positive for SARS-CoV-2 (ie, those who were exposed) were matched on sex, age, and collection date of RT-PCR test at a 1:4 ratio to those who tested negative (ie, those who were unexposed). Analysis was conducted January 14, 2022, to January 19, 2023.
Main Outcomes and Measures
The primary outcome was incident diabetes (insulin dependent or not insulin dependent) identified more than 30 days after the specimen collection date for the SARS-CoV-2 test with a validated algorithm based on medical visits, hospitalisation records, chronic disease registry, and prescription drugs for diabetes management. Multivariable Cox proportional hazard modelling was performed to evaluate the association between SARS-CoV-2 infection and diabetes risk. Stratified analyses were performed to assess the interaction of SARS-CoV-2 infection with diabetes risk by sex, age, and vaccination status.
Results
Among 629 935 individuals (median [IQR] age, 32 [25.0-42.0] years; 322 565 females [51.2%]) tested for SARS-CoV-2 in the analytic sample, 125 987 individuals were exposed and 503 948 individuals were unexposed. During the median (IQR) follow-up of 257 (102-356) days, events of incident diabetes were observed among 608 individuals who were exposed (0.5%) and 1864 individuals who were not exposed (0.4%). The incident diabetes rate per 100 000 person-years was significantly higher in the exposed vs non-exposed group (672.2 incidents; 95% CI, 618.7-725.6 incidents vs 508.7 incidents; 95% CI, 485.6-531.8 incidents; P < .001). The risk of incident diabetes was also higher in the exposed group (hazard ratio [HR], 1.17; 95% CI, 1.06-1.28) and among males (adjusted HR, 1.22; 95% CI, 1.06-1.40). The risk of diabetes was higher among people with severe disease vs those without COVID-19, including individuals admitted to the intensive care unit (HR, 3.29; 95% CI, 1.98-5.48) or hospital (HR, 2.42; 95% CI, 1.87-3.15). The fraction of incident diabetes cases attributable to SARS-CoV-2 infection was 3.41% (95% CI, 1.20%-5.61%) overall and 4.75% (95% CI, 1.30%-8.20%) among males.
Conclusions and Relevance
In this cohort study, SARS-CoV-2 infection was associated with a higher risk of diabetes and may have contributed to a 3% to 5% excess burden of diabetes at a population level.
See more from MedicalBrief archives:
COVID patients likelier to develop CVD, diabetes, post-infection – London study
Long COVID can trigger type 2 diabetes in some – VA cohort study
More evidence that diabetes/overweight tied to severe COVID-19 — Hospital meta-analysis