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  • Whether or not viral infections can increase the risk of developing diabetes has been the focus of research for some time.
  • Now, scientists are asking if SARS-CoV-2 infection, the virus that causes COVID-19, can increase the risk of diabetes.
  • New data suggests the COVID-19 pandemic could have increased the total disease burden of diabetes by 3-5% in the Canadian population.
  • This data supports calls for increased surveillance of blood sugar levels in COVID-19 survivors to minimize further harm to affected individuals.

The COVID-19 pandemic has so far resulted in nearly 7 million deaths, according to the World Health Organization (WHO), and the full impact on the global population’s health has yet to be realized.

Much of the impact of SARS-CoV-2 infection— the virus that causes COVID-19—could be from its effects on long-term health. Even those who experienced a mild infection could be affected by long-term side effects, including long COVID, which is thought to affect 10-30% of people with mild infections, and over half of those who are hospitalized.

A recent study has shown that infection with SARS-CoV-2 was associated with a 3-5% increase in the total diabetes disease burden in Canada in 2020 and 2021.

The results have been published in JAMA Network Open, alongside an editorial investigating the implications of the findings.

This is not the first time that research has highlighted the potential link between SARS-CoV-2 infection and diabetes.

A U.S.-based retrospective cohort study published in the BMJ in May 2021 demonstrated a significantly increased incidence of diabetes among individuals following infection. Another paper published a month earlier in Nature, showed an increased risk of diagnosis with metabolic disorders following infection, including diabetes.

Later that year, a study published in Cell Metabolism demonstrated SARS-CoV-2 could infect human pancreatic β cells which make insulin, and are damaged and eventually lost in individuals with diabetes. Infection could also lead to the loss of these cells, pointing to a potential underlying mechanism to explain the association.

Since then, cohort studies, such as that published in Diabetologia, pointed towards a higher incidence rate of type 2 diabetes, but not type 1 diabetes, after infection. Another retrospective cohort study using Veterans Health Administration data published in Diabetes Care showed an increased incidence of all diabetes diagnoses after SARS-CoV-2 infection in men, but not in women.

Type 1 diabetes tends to be diagnosed in children rather than adults, and a cohort study including children published in PLOS One showed an increased risk for type 1 diabetes diagnosis after infection, and that risk was further increased for those from American Indian/Alaskan Native, Asian/Pacific Islander, and Black populations.

Now, a study of 629,935 adults, with an average age of 32, has shown that men who tested positive for SARS-COV-2 from January 1, 2020, to December 31, 2021, were 22% more likely to develop diabetes in the eight months following infection than men who hadn’t been infected.

Researchers created matched pairs of those who had a confirmed case of COVID-19 and those who hadn’t been infected, based on age, sex, and date of infection from the British Columbia COVID-19 Cohort, a database of SARS-CoV-2 infection in British Columbia, Canada.

Researchers stratified the results according to the severity of disease and found that those who were admitted to hospital with COVID-19 were 2.4 times more likely to develop diabetes than those who hadn’t been infected, and those who were admitted to intensive care were 3.29 more likely to develop diabetes.

When these cases were taken into account, the data showed that women were also more likely to develop diabetes after infection with SARS-CoV-2, though this trend was not significant when only mild cases were considered.

This association was only found for non-insulin-dependent diabetes, and authors were not able to distinguish between type 1 and type 2 diabetes using the data they had available to them.

Similar to other long-term effects of SARS-CoV-2 infection, it is unclear exactly what the underlying mechanism is. While this isn’t the first time a viral infection has been linked to an increased risk of developing diabetes, it is unclear what mechanisms underlie the association.

Dr. Fares Qeadan, associate professor of biostatistics at Loyola University Chicago, who was not involved in the research, told Medical News Today that the impact of Coxsackievirus B infection on type 1 diabetes risk has been widely studied, as well as mumps, rubella, and cytomegalovirus.

Researchers have also studied the impact of hepatitis C virus infection on the risk of developing type 2 diabetes with attention to potential mechanisms involving inflammation, insulin resistance, and effects on pancreatic β cells.

“To summarize, viral infections have been associated with an increased risk of both type 1 and type 2 diabetes. For type 1 diabetes, the evidence is more robust and involves a variety of viruses, while the evidence for type 2 diabetes is less extensive and mostly focuses on specific viral infections such as hepatitis C virus. Further research is needed to elucidate the exact mechanisms by which viral infections contribute to the development of diabetes and to develop preventive strategies.”
— Dr. Fares Qeadan

Type 1 diabetes is typically diagnosed in children, and type 2 diabetes in adults. This difference is highlighted by the authors of the editorial, also published in JAMA Network Open, who point out that adult-only cohorts are therefore less likely to pick up the association with type 1 disease.

Whether or not the development of diabetes after infection with SARS-CoV-2 could be considered a symptom of long-COVID was a complicated question, experts warned as the clinical characterization of long COVID is still being developed.

Dr. Morgan Birabaharan, a doctor and virus researcher from the Division of Infectious Diseases and Global Public Health at the University of California, San Diego, who was not involved in the research, told MNT:

“The development of diabetes may fit under the umbrella of long COVID, which describes a wide array of symptoms and diseases that develop after the acute phase of SARS-CoV-2 infection (>30 days).

“However, since we are still trying to understand the pathophysiology of long COVID, whether it be persistent viremia, dysregulated immune response, or some other phenomenon, it’s hard to group what complications of SARS-CoV-2 infection are ‘long COVID’ vs. some other process,” he explained.

The population-level impact of an increase in the number of diabetes cases due to the COVID-19 pandemic could also be significant, and this latest paper supported calls for proactive management of this.

“In any case, recognizing the potential association between SARS-CoV-2 infection and the development of diabetes is important for healthcare providers, as it underscores the need for close monitoring of blood glucose levels and early intervention in individuals who have had COVID-19,” Dr. Qeadan said.

“This can help minimize the long-term impact of diabetes on the affected individuals and reduce the overall burden on healthcare systems,” he added.