Does COVID-19 infection increase my risk of diabetes?


A: A new study published in The Lancet suggests that people who had a COVID-19 infection are at increased risk of developing diabetes within a year. Research is piling up to show that COVID-19 infections can result in long term health consequences.

Last month, a study was published in the medical journal The Lancet asking this very question. They looked at about 180,000 patients at the US Department of Veterans Affairs who had a COVID-19 infection and compared them to more than 4 million people who did not have a known infection. This is called a cohort study. Cohort studies follow a group of people that have something in common (like they all had COVID) and compare them to a control group (people who do not have that common characteristic). These types of studies are often used to look for potential cause and effect.

In this study, folks who had a known COVID-19 infection were about 40% more likely to develop diabetes in one year than people who did not have COVID-19. The absolute risk increase was about 1% (4.08% of the COVID-19 infected group developed diabetes and 3.10% of the control group developed diabetes). While a 1% absolute risk increase may seem small, this would be a big impact over the millions of folks who had a COVID-19 infection. There was an increased risk even for people who had mild or moderate infections.

Of course, this is only one study, so the link is not definitive (but it is concerning). One weakness of cohort studies is the large number of potential confounders, or variables that can impact the result and make something look associated even though it isn’t. This study tried pretty darn hard to control for possible confounders, like age, other health problems, and smoking status. However, there is always a chance that another variable is mucking up the results. It is also possible that people already had diabetes but were not diagnosed until after they got COVID-19, making it look like COVID causes diabetes. Inversely, people in the control group also may have had COVID at some point, but didn’t know it. If they got diagnosed with diabetes in that time, it would look like it wasn’t associated with COVID-19, falsely lowering the estimated risk of diabetes after COVID. You can see why results can get a little muddy and why it is important to repeat studies to make sure the link holds true.

So, what is the takeaway here? There is growing evidence that COVID-10 infections can have long term health consequences, even for people who had mild symptoms. This study reinforces how important prevention is and why we don’t want to get COVID if we can avoid it. Masks and good ventilation are evidence-based ways to reduce the risk of infection. Vaccination and boosters remain critical. If you haven’t yet been vaccinated or boosted, it’s not too late!

Stay Safe. Stay Sane.
Those Nerdy Girls


The Lancet Article

NPR Coverage of the Study

Cohort Studies Explained

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