It’s well-established that diabetes increases the risk of falling severely ill with Covid-19, but there’s some evidence that this relationship might also go the other way: Covid-19 appears to be associated with new-onset diabetes. Scientists are now digging into the question of whether Covid-19 can trigger the emergence of diabetes in some people.
A letter published in June by the New England Journal of Medicine (NEJM), signed by an international group of 17 leading diabetes experts, warned of a number of reports showing new cases of a diabetes-like illness in patients with Covid-19. Many of the researchers from the letter are also closely involved with CoviDiab, an international effort to create a global registry of new-onset Covid-19 related diabetes. Reuters reported this week that they’ve already collected over 300 reports from around the world, but they expect that number to grow as the pandemic continue to rumble on
In many of these cases, people with no history of diabetes suddenly got hit with hyperglycemia – dangerously high levels of sugar in the blood that occurs when the body does not produce or use enough insulin – after being diagnosed with Covid-19. While this does not explicitly describe diabetes brought on by Covid-19, it’s a link that many scientists think is worth investigating.
Another study by Imperial College London shows that hospitals in northwest London saw an unusually high number of new cases of type 1 diabetes in children during the peak of the pandemic’s first wave compared to previous years. On closer inspection, it was revealed that many – but not all – of these kids tested positive for Covid-19.
However, the link is hazy and there are many unknowns surrounding the relationship. As pointed out by the letter authors in the NEJM, doctors are not sure whether this diabetogenic effect of Covid-19 is classic type 1 or type 2 diabetes or a new type of diabetes.
"We don't yet know the magnitude of new-onset diabetes in Covid-19 and if it will persist or resolve after the infection; and if so, whether or not or Covid-19 increases risk of future diabetes,” Professor Paul Zimmet, Honorary President of the International Diabetes Federation and letter signatory, said in a statement.
Nevertheless, there are a few theories of how this condition might come about.
Firstly, it’s known that viral infections can trigger the onset of type 1 diabetes, an autoimmune disease that causes the insulin-producing cells in the pancreas to be destroyed, which prevents the body from regulating blood glucose levels. One of the most prominent links has been found between developing type 1 diabetes and children exposed to enteroviruses, a large group of viruses that includes everything from mild common cold bugs to polio.
It’s thought enteroviruses and other viruses may spark type 1 diabetes as they appear similar to parts of insulin-producing cells in the pancreas, causing the immune system to mistakenly attack the cells. Alternatively, the infections might slightly change the insulin-producing cells, making them appear as a threat to the immune system. A similar response could be occurring with SARS-CoV-2, the virus that causes Covid-19.
Secondly, it’s known that Covid-19 can directly affect organs and tissues involved in glucose metabolism, such as the pancreas, small intestine, fat tissue, liver, and kidney. It’s plausible that SARS-CoV-2 may damage these organs and alter glucose metabolism, which could lead to diabetes and poor glycaemic control.
Other scientists are more skeptical of the idea Covid-19 can trigger diabetes, arguing that there is currently not enough robust evidence to support this significant claim. However, our knowledge of the unusual qualities of Covid-19 is expanding by the day as increasingly more data is made available. It's also becoming increasingly obvious that Covid-19 is a multi-organ disease that can affect the body in many unusual and unexpected ways. Though the evidence isn't definitive, it seems worth exploring this apparent link.
“[I]t would be unfair to take the cited data to indicate that Covid-19 is causal of diabetes and diabetes complications but, given the observations, it is reasonable to propose to look at this carefully, as proposed in the letter," Dr Gabriela da Silva Xavier, Senior Lecturer in Cellular Metabolism at the University of Birmingham in the UK, commented in June.