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Exploring research: Why does coronavirus affect people with diabetes?

Although we don’t yet fully understand why people with diabetes are more likely to become seriously ill with coronavirus, we take a look at some of the theories about inflammation, damaged blood vessels and ACE-2 receptors to find out more.

A picture of Faye, our Senior Research Communications Officer and the author of our series about the key things to know about coronavirus and diabetes research

Written by Faye Riley PhD, our Senior Research Communications Officer. This article is part of our series on the key things to know about coronavirus and diabetes research.  

Shared risk factors 

Our age, ethnicity and health all impact our risk of getting seriously ill from coronavirus. And we also know the risk factors for developing type 2 diabetes are similar. But why does coronavirus affect people with diabetes?

People with type 2 diabetes are usually older, and we see higher rates of type 2 diabetes in people of Black African, African Caribbean and South Asian backgrounds. People with diabetes may also live with other health conditions, like high blood pressure or kidney disease.

The shared risk factors partly help to explain why people with diabetes have a higher chance of developing a serious illness if they get coronavirus. But we also know that when we account for other coronavirus risk factors, diabetes itself still remains a risk factor. This means the effect of diabetes on the body must play a part in how coronavirus affects people with the condition.


High blood (glucose) sugar levels can cause inflammation inside our body. As coronavirus also triggers inflammation, one possible theory could be that people with diabetes may be experiencing this more severely.

Too much inflammation can cause our immune system to go into overdrive. This means that instead of fighting an infection, it can start to attack healthy parts of our body and vital organs.

This is known as a cytokine storm, and higher levels of inflammation could mean people with diabetes are more likely to experience it. This might explain why lower blood sugar levels have been linked to people with diabetes not getting as ill from coronavirus.

Damaged blood vessels 

Our blood vessels have a layer of cells around them, which act as a barrier between our blood and tissue. This barrier blocks certain substances from entering our tissue.

When you have diabetes, high blood sugar levels can damage your blood vessels over time. This can cause the barrier between the tissue and blood to breakdown. Scientists think that this breakdown could potentially make it easier for coronavirus to travel around and affect the body.

To explore this theory more, we’re funding Dr Miguel Bernabeu at the University of Edinburgh. He’s studying people who have retinopathy to investigate if damage to the blood-tissue barrier in their eye allows the virus to travel to organs like the brain and heart. He will investigate if this can explain why people with retinopathy may be more likely to get seriously ill from coronavirus. 

ACE-2 receptor 

Lastly, we know that coronavirus uses a protein, called ACE-2, that’s found on the surface of cells as its doorway to enter and infect cells in the body.

There’s some evidence that suggests that higher levels of ACE-2 are found in people with diabetes, and this could potentially give the virus more doors to open and more opportunity to infect the body. 

It could also be a combination of all these factors coming together that explain why people with diabetes may become seriously ill from coronavirus. With more research, we’ll get a better understanding of what is happening inside the body in people with diabetes, and this will be key to improving treatments and protecting them from the virus. 

More things to know about coronavirus research

We know that you may have more questions about coronavirus and diabetes, so we've taken a look at the research to bring you the key things to know. Find out more about:

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