Covid-19 can cause insulin-producing pancreatic cells to become infected and alter their function. This could explain why people who were previously healthy develop diabetes.
Doctors are becoming more concerned about the rising number of diabetes cases in patients who were either infected by coronavirus or after recovery.
There are many theories to explain the increase in insulin resistance. One theory is that the virus infects pancreatic cancer cells through the same ACE2 receptor on the surface cells of lung cells. This causes insulin resistance, which can lead to pancreatic cell damage. Another possibility is that an excessive antibody response to the virus may cause pancreatic cell death.
Professor Shuibing Chen from Weill Cornell Medicine in New York examined a variety of cells and organoids. He created clusters of cells in a lab that mimics the functions of organs in order to determine if they could have been infected with Covid. These results indicated that the lung, colon, liver, pancreatic, and heart organoids could all have been infected. Dopamine-producing brain cells could also be affected.
Further research revealed that the insulin-producing beta cells in the pancreas are also susceptible to infection. These cells produce less insulin and other hormones than those produced by other pancreatic cells.
We call it transdifferentiation, said Chen, who presented the results at the annual meeting of the European Association for the Study of Diabetes on Wednesday. They are basically altering their cellular fate. Instead of being beta cells that secrete lots of insulin, they mix different hormones. This could give us a better understanding of the pathological mechanisms behind Covid-19.
Scientists have seen a similar phenomenon in type 2 diabetics, though it is more closely linked to the body's tissue becoming less responsive.
The long-term effects of Covid infection remain unknown. Chen stated that although some patients had extremely unstable glucose levels during their stay in intensive care, they recovered from Covid-19. This suggests that not all patients will experience permanent changes.
Separate research by Prof Francesco Dotta at the University of Siena in Italy and colleagues confirmed that Covid attacks pancreatic cells by targeting the angiotensin-converting enzyme 2 (ACE2) protein on their surface, and that insulin-producing beta cells express particularly high levels of this protein.
The researchers also showed that ACE2 levels increased in inflammatory conditions. This is important as people with type 2 diabetes may already have inflammation in their pancreas. Dotta stated that this could make insulin-producing beta cells more vulnerable to viral infection if they become inflamed.
This could indicate that patients with diabetes or prediabetes may be at higher risk for pancreatic dysfunction if they get Covid-19, something Dotta plans to investigate. Dotta said that although patients with diabetes are less likely to contract Covid-19 infection due to their frequency, they can develop severe complications and metabolic disorders once they have been infected.
Professor Francesco Rubino of the Kings College London's metabolic surgery chair said that these studies support the biological argument that Covid-19 may increase the chance of developing diabetes in those who are predisposed or completely unprepared.
Co-leading an international effort, he is establishing a global Covid-19-linked diabetic case database to better understand if the infection can trigger a stress response and lead to type 1 or 2 diabetes.
These studies don't answer the question of whether such changes would be enough to allow this virus to cause diabetes, but they do give us another reason to believe it is possible, he stated.
This is not the only way that the virus can increase diabetes risk. Rubino stated that one thing we were seeing was that patients with type 1 diabetes may have severe insulin resistance in certain cases. This is an egregious feature of type 2 diabetes. This could indicate a problem in how other cells respond to insulin after Covid-19 infections.
Dr Lucy Chambers, Head of Research Communications at Diabetes UK said that Covid-19 has had a disproportionality effect on people with diabetes and that many have died tragically as a consequence. Covid-19 is known to be a risk factor for diabetes and other serious illnesses. However, it is unclear how Covid-19 might trigger new cases of diabetes.
This research reveals more about the biological interactions between diabetes and Covid 19. This research will allow us to develop new and more effective ways of treating people with Covid-19 who are at risk or already have diabetes. The best protection against the virus is to continue receiving the Covid-19 vaccine, which includes a booster if offered.
