Can COVID-19 Cause Diabetes?

Recent research has pointed to a connection between so-called “long COVID” (COVID-19 infections with symptoms that last several weeks or even months) and the development of Type 2 diabetes. The study shows that within a year of recovering from a COVID-19 infection, people were about 40% more likely to develop diabetes.

Before you go jumping to any conclusions, though, remember: Correlation doesn’t equal causation. In other words, just because there’s a relationship between the two doesn’t prove one causes the other. There’s still much more research to be done.

But it may feel as though we’ve been living with the COVID-19 pandemic for a long time. We’ve been through so many changes to our “normal,” and we’ve learned so much about protecting ourselves and others from infection. In the world of scientific research, however, these are still very early days. We’re far from having answers to a lot of questions.

“Whenever we think about chronic disease processes, such as diabetes, we need to look at things in a longitudinal fashion, meaning tracking things over a period of five to 10 years at least, to really see what is happening,” says critical care physician Abhijit Duggal, MD. “It’s simply too early to say why we’re seeing the trends we’re seeing between COVID-19 and diabetes.”

We talked with Dr. Duggal about what we know and what we don’t know yet about the chances of developing diabetes after a COVID-19 infection.

What does the research show?

One early study compared 180,000 people who had been infected with COVID-19 to people who weren’t infected. The findings showed that the group that had been infected with COVID-19 had higher rates of diabetes that hadn’t been diagnosed before. The connection between COVID-19 infection and diabetes was higher among people who had more serious infections and were hospitalized.

For every 1,000 people studied, 13 more people in the group who had contracted COVID-19 were diagnosed with diabetes compared with the non-COVID-19 group. That may seem like a small number, but when you consider that nearly 100 million people in the United States have been infected with COVID-19, it adds up fast — to about 1.3 million more cases of diabetes.

The authors of the study have previously shown connections between COVID-19 and increased kidney disease, heart failure and stroke.

What doesn’t the research tell us?

What’s yet to be determined, though, is whether the correlation between long COVID and diabetes actually means that COVID-19 is causing diabetes.

Consider this: A seaside town notices that as ice cream sales rise, so do the number of shark attacks. Does that mean eating ice cream makes you secrete delicious ice cream-scented sweat that makes you irresistible to a Great White? Or does it mean that on hot days, people are more likely to eat ice cream and also more likely to swim in shark-infested waters? One of those hypotheses may seem more likely than the other, but without further research, who can say for sure?

The same is true of the association between COVID-19 and diabetes, Dr. Duggal says.

It could be that a COVID-19 infection triggers changes in your body that can lead to diabetes in some people.

Or it may be that the same people who are more susceptible to acquiring long COVID are the same people who are at higher risk for developing diabetes.

Or perhaps it’s that when you’re living with long COVID, you’re more likely to see a doctor than you otherwise would be and, therefore, your diabetes — which would have otherwise gone undiagnosed — is found.

There are cases where infections, like the herpes virus, for example, can lead to pancreatitis, which can lead to diabetes. So, it wouldn’t be unheard of for COVID-19 to cause diabetes. It’s just not something we know yet.

“There is definitely an association between diabetes and COVID, but more studies need to come out to really be able to tell us whether there is a causal relationship between COVID-19 and diabetes,” Dr. Duggal notes. “That will take time, but there are people working on this.”

Look out for signs of diabetes

If you’ve had COVID-19 (or if you have other risk factors for diabetes), Dr. Duggal says you should be on the lookout for diabetes symptoms, like:

• Blurred vision.
• Fatigue.
• Feeling very hungry or thirsty.
• Increased need to urinate (usually at night).
• Slow healing of cuts or sores.
• Tingling or numbness in your hands or feet.
• Unexplained weight loss.

Recognizing these signs of diabetes will help get a proper diagnosis and treatment plan in place to best manage your condition. Talk with a healthcare provider if you think you may be developing symptoms of diabetes.

While we don’t know yet whether COVID-19 is causing diabetes, we do know a COVID-19 infection is associated with an increased risk for diabetes. Research is ongoing but it will be some time before we know for sure why these conditions are connected. In the meantime, take precautions to protect yourself from COVID-19 infection and, again, talk with a healthcare provider about your risk for diabetes.

And steer clear of sharks after eating ice cream. You never know.