A group of scientists from around the world believes that there is a growing body of evidence that Covid-19 can cause diabetes in some patients.
Professor Francesco Rubino, from King’s College London, is leading the call for a thorough investigation into a possible link between the two diseases. Having seen an increase in type 1 and type 2 diabetes in people who have contracted the coronavirus, some doctors are even considering the possibility that the virus – by disrupting sugar metabolism – may be inducing an entirely new form of diabetes.
Rubino realized for the first time the possibility of a link during a tea with colleagues at Zoom, where anecdotal cases were being exchanged.
Rubino and others set up a registry to start grouping and analyzing these reports. Lead investigators in the registry, who have received reports from more than 350 individual doctors who suspect they have found one or more cases of Covid-induced diabetes, said the numbers were hard to ignore.
“In the past few months, we have seen more cases of patients who developed diabetes during the experience with Covid-19 or shortly thereafter. Now we are starting to think that the link is probably true – there is an ability of the virus to cause sugar metabolism to malfunction, ”said Rubino.
If there was a biological link, it would be difficult to prove without a substantial database, he noted. “We said it is worth starting an investigation because that – especially due to the size of the pandemic – can be a significant problem.”
Patients with pre-existing diabetes are at increased risk of serious complications with Covid-19 and are on the UK’s priority list for receiving the vaccine. The links between other viruses and diabetes, and the way the Sars-CoV-2 virus, which causes Covid-19, penetrates into various organs, has raised concern.
“In my own mind, there is no doubt. Covid-19 is certainly a cause of new diabetes, ”said Paul Zimmet, professor of diabetes at Monash University in Australia. “But we still don’t fully understand – firstly, the magnitude and, secondly, which of the things we hypothesized are the main factors.”
Scientists have hypothesized that since Sars-CoV-2 interacts with a receptor called ACE-2 to infiltrate cells in a number of organs, including the pancreas, it may be disrupting sugar metabolism. Another potential explanation is the body’s exuberant antibody response, which aims to fight the virus, overreacts and attacks essential organs to maintain normal glucose levels.
“Now, these are all theories … theories that are not philosophical, but based on biology and experience with other viruses,” said Rubino, who is president of bariatric and metabolic surgery.
Other viruses – particularly enterovirus infections – have been linked to causing type 1 diabetes, in which the body attacks the cells of the pancreas by preventing the production of insulin. Enterovirus antibodies have been recorded at higher levels in pregnant mothers of children who have developed type 1 diabetes, and more enterovirus infections tend to be detected in children who develop the disease, compared to siblings who do not.
Dr. Sathish Thirunavukkarasu, a researcher at McMaster University in Canada, conducted a review covering eight studies from different countries in the first five months of the pandemic. Thirunavukkarasu and colleagues found 492 newly diagnosed combined cases of diabetes among 3,711 hospitalized Covid-19 patients, or a combined proportion of 14.4%.
Those numbers include patients with Covid-19 who were diagnosed with diabetes for the first time, as well as people who already had diabetes – but did not know they had the disease, he explained.
It is difficult to ignore the dramatic symptoms of type 1 diabetes, in which the body does not produce insulin. But in the case of type 2 diabetes – where the body is unable to produce enough insulin or the insulin does not function properly – the symptoms are easy to ignore because they appear gradually.
About 3.9 million people in the UK were diagnosed with diabetes in 2019, but doctors believe there are thousands who remain undiagnosed, a statistic that has probably worsened because of the pandemic.
Ian Braithwaite, NHS physician and co-founder of Habitual, a diabetes prevention and reversal company, pointed out that the analysis by Thirunavukkarasu and colleagues was also limited to hospitalized patients, so it was not clear whether the cases of diabetes persisted as they recovered. or if the increase in sugar levels puts patients at risk of developing diabetes.
An increase in sugar levels may have nothing to do with diabetes, but with the body’s response to infection. In addition, the steroids used to treat certain patients with Covid-19 are also known to raise blood sugar levels, doctors said.
Other recent studies have linked Covid-19 to diabetes to varying degrees. Researchers in China who followed 2,469 patients from Covid-19 after being discharged from the hospital for six months reported 58 (about 2.35%) cases of recent onset diabetes. A separate study, still to be peer-reviewed, which looked at the results of 47,780 patients with Covid-19 within five months of hospital discharge in England, found that 4.9% of patients were diagnosed with diabetes after discharge.