A group of scientists from around the world believe that there is evidence that Covid-19 can cause diabetes in some patients.
Prof Francesco Rubino, from King’s College London, is calling for a full investigation into a possible link between the two diseases. Some doctors are considering the possibility that the virus, by interrupting sugar metabolism, could cause a completely new form of diabetes, as an increase in both type 1 and type 2 diabetes has been seen in people who have contracted coronavirus.
Rubino first realizes the possibility of a link during a tea party with colleagues over Zoom where anecdotal matters are exchanged.
Rubino and others have compiled a registry to compile and analyze these reports. The registry’s chief investigators, who have received reports from more than 350 individual clinicians suspected of having experienced one or more cases of Covid-induced diabetes, said the numbers are hard to ignore.
‘In the last few months we have seen more cases of patients who had diabetes during or shortly after the Covid-19 experience. We are now beginning to think that the connection is probably true. “There is the ability of the virus to cause a malfunction of the sugar metabolism,” said Rubino.
If there was a biological connection, it would be difficult to prove without a substantial database, he noted. “We said it was worth investigating because, especially given the size of the pandemic, it could be a big problem.”
Patients with pre-existing diabetes have a higher risk of serious complications with Covid-19 and are on the UK priority list to receive the vaccine. Links between other viruses and diabetes and the way in which the Sars-CoV-2 virus that causes Covid-19 to enter various organs has caused concern.
“In my opinion, there is no doubt. Covid-19 is definitely a cause of new diabetes, ”said Paul Zimmet, professor of diabetes at Monash University in Australia. “But we do not yet fully understand – firstly the extent and, secondly, which of the things we assumed were the most important factors.”
Scientists have suggested that Sars-CoV-2 interacts with a receptor called ACE-2 to infiltrate cells in a variety of organs, including the pancreas, so that it can disrupt sugar metabolism. Another possible explanation is the exuberant antibody response of the body, which is meant to fight the virus, overreact and attack the organs, which is the key to maintaining normal glucose levels.
“These are all theories … theories that are not philosophical but based on biology and experience with other viruses,” Rubino said. He is chair of metabolic and bariatric surgery.
Other viruses – especially enterovirus infections – are associated with type 1 diabetes, in which the body attacks the cells in the pancreas that inhibit the production of insulin. Teenovirus antibodies have been detected at higher levels in pregnant mothers of children who have developed type 1 diabetes, and more enterovirus infections are usually detected in children who develop the condition, compared to siblings who do not.
Dr Sathish Thirunavukkarasu, a researcher at McMaster University of Canada, conducted a review of eight studies from different countries from the first five months of the pandemic. Thirunavukkarasu and colleagues collectively found 492 cases of newly diagnosed diabetes among 3,711 hospitalized Covid-19 patients, or a combined percentage of 14.4%.
These figures include both Covid-19 patients who were first diagnosed with diabetes and people who had diabetes before – but did not know they had the disease, he explained.
It is difficult to ignore the dramatic symptoms of type 1 diabetes, where the body makes no insulin. But in the case of type 2 diabetes – in which the body cannot make enough insulin or if the insulin is not working properly – it is easy to miss symptoms, because it occurs gradually.
About 3.9 million people in the UK have been diagnosed with diabetes since 2019, but doctors believe there are thousands who have not been diagnosed, a statistic that has probably worsened due to the pandemic.
Ian Braithwaite, an NHS doctor and co-founder of Habitual, a diabetes prevention and reversal company, pointed out that the analysis by Thirunavukkarasu and colleagues was also limited to patients in the hospital, so it was not clear whether the cases of diabetes continue they have recovered, or the increase in sugar levels puts patients at risk for diabetes.
An increase in sugar levels can have nothing to do with diabetes and everything to do with the body’s response to infection. In addition, steroids used to treat certain patients with Covid-19 are also known to increase blood sugar levels, doctors have stressed.
Other recent studies have linked Covid-19 to varying degrees to new diabetes. Researchers in China who tracked down 2,469 Covid-19 patients after being discharged from hospital six months ago recorded 58 (about 2.35%) cases of new diabetes. In a separate, peer-reviewed study examining the results of 47,780 Covid-19 patients within five months of hospital discharge in England, it was found that 4.9% of patients were diagnosed with diabetes after discharge.