Physicians are warning in a letter published this month in The New England Journal of Medicine that COVID-19 can cause diabetes.
“There is a bidirectional relationship between COVID-19 and diabetes. On the one hand, diabetes is associated with an increased risk of severe COVID-19,” the doctors, who hail from different universities, wrote in the letter. “On the other hand, new-onset diabetes and severe metabolic complications of preexisting diabetes have been observed in patients with COVID-19.”
One case report from Singapore shows that a previously healthy 37-year-old developed severe diabetes after he tested positive for SARS-CoV-2, the coronavirus that causes COVID-19.
“As far as SARS-CoV-2 and the COVID-19 infection, this is all very new and emerging data. The mechanisms for causing acute diabetes and both short- and long-term clinical outcomes are not fully known,” said Melissa Young, spokeswoman for the Association of Diabetes Care and Education Specialists (ADCES). “However, data are showing that individuals with diabetes are at high risk for severe complications and death from COVID-19.”
Ms. Young noted that studies refer to metabolic complications as contributing factors for severe COVID-19 symptoms, adding that people with high blood sugar are thought to be at highest risk.
“Chronic hyperglycemia [high blood sugar] decreases the body’s ability to fight viruses by suppressing the immune system. In addition, approximately 90% of individuals living with Type 2 diabetes and about 50% of those living with Type 1 diabetes are overweight and/or obese,” she said, noting that high blood sugar and being overweight or obese can increase inflammation in the body.
“COVID-19 can also cause severe inflammation, increasing risk for severe complications. This is the same for the seasonal influenza,” Ms. Young said.
There are other instances of coronaviruses triggering diabetes: During the 2002-2003 SARS (severe acute respiratory syndrome) outbreak in China, some patients with pneumonia caused by the coronavirus developed acute onset diabetes. After three years, the diabetes in most patients went away but remained in 10% of patients, according to a 2009 study published in SpringerLink. Several viruses have been linked to diabetes, including enteroviruses, rotavirus and the mumps virus. It also has been suggested that rubella virus can cause Type 1 diabetes.
“We have known for many years that viral infections may be linked to the first time a patient has diabetes symptoms. (Type 1 diabetes presents in a seasonal fashion, a fact often seen with viral infections.) And viral infections may also trigger the destruction of the insulin-producing islet cell “factories” in the pancreas, setting up a chronic autoimmune response,” Dr. Julian Hamilton-Shield, professor in diabetes at the University of Bristol, wrote in an article for TheConversation.com.
Dr. Hamilton-Shield said it is unclear if COVID-19 can cause Type 1 or Type 2 diabetes, speculating that this could be a new form of diabetes, but right now there is too little data.
To gather more data, the authors of The New England Journal of Medicine letter created a global registry to record COVID-19 related diabetes cases.
While evidence points to worse outcomes of COVID-19 for people with diabetes, there is not enough data to show that these individuals are more likely to contract the virus than the general population, says the American Diabetes Association.
About 34 million people in the U.S. or 10.5% of the population have diabetes, according to the latest data from the Centers for Disease Control and Prevention. The percentage of adults with diabetes increases with age, hitting close to 27% among those 65 years and older. In the U.S., the coronavirus has infected more than 2.2 million people and killed more than 120,000 as of Monday afternoon, data from Johns Hopkins University shows.