It has been nearly three years since the first case of the new coronavirus (SARS-CoV-2) was detected. At first there were fears that people with diabetes may be at greater risk of getting COVID-19, but this does not seem to be the case.

However, having diabetes and hyperglycaemia (high blood glucose levels) are risk factors for a more severe COVID-19 infection. Why is this so?

Are diabetes and COVID-19 connected?

There does seems to be a connection between diabetes and COVID-19. Diabetes is a risk factor for getting more severe COVID-19, but new evidence now suggests that COVID-19 may actually trigger the development of diabetes.

People with diabetes may get more severe COVID-19 because high blood glucose levels can increase the risk of infections. It could also be that the infection itself can affect your immune system.

Some people believe that inflammation caused by the virus can bring about insulin resistance, which is linked to type 2 diabetes.

A group of researchers found that a particular protein, called angiotensin-converting enzyme 2, or ACE2, may play a role. ACE2 is produced in your kidneys, intestines, heart, blood vessels, lungs and pancreas. ACE2  makes it easier for the coronavirus to enter your body as one of the spikes of the coronavirus binds to ACE2. This is particularly the case in the new Omicron variant.

When there is a sudden sharp rise in your blood glucose levels your body may become more sensitive to this ACE2 and this can make it even easier for the coronavirus to enter your cells.

Although COVID-19 enters your body through the lungs, it can easily spread throughout your body once it is connected to this ACE2. As your pancreas is one of the organs in which ACE2 is made it is possible that it damages the islet cells in the pancreas that are responsible for making insulin.

Perhaps the immune system accidentally attacks insulin-producing cells as it is attacking something else in the same area, for example COVID-19. It could be that COVID-19 is causing some people’s immune system to do just that.

The rising levels of diabetes could also be linked to the impact of the pandemic restrictions. Some people have delayed seeking medical care out of fear of infection with COVID-19. For others it could be relating to changes in physical activity levels or food choices.

As COVID-19 is so new, there is a lot that we still need to learn about how it interacts with the immune system and how it affects different organs.

COVID-19 treatment can cause hyperglycaemia

A steroid medication called Dexamethasone is often used to treat people with severe COVID-19 who need oxygen treatment. Dexamethasone can cause insulin resistance and hyperglycaemia, even in people who do not have diabetes. It can also cause people with diabetes to need more insulin than usual to lower their blood glucose to target levels.

Some people with diabetes who get COVID-19 may develop ketoacidosis or hyperosmolarity.

Ketoacidosis is a serious condition that can happen when the level of ketones in the blood is too high. The liver makes ketones by breaking down fat. It does this when there is not enough insulin in the body to allow the use of glucose for energy. The ketones enter your bloodstream and this makes the blood too acidic. Ketones in large amounts are toxic for your body.

Hyperosmolarity is a condition in which the blood has a high concentration of glucose, salt and other materials. These pull water out of the body’s other organs, leading to severe dehydration.

Both ketoacidosis and hyperosmolarity are treated with intravenous fluids (a ‘drip’) and high doses of insulin. Some people who take tablets for their diabetes may need insulin treatment instead during this time.

COVID-19 and the development of diabetes

Research from around the world has shown larger numbers than expected of new cases of diabetes in people who had COVID-19. But many of these studies are done in ways that make it hard to compare the findings and draw conclusions. For example, some studies only looked at children, others only at adults.

It seems that the chance of developing diabetes is highest in the first four weeks after getting COVID-19. It appears that the risk of developing diabetes, for people who did not have diabetes before COVID-19, is not increased long-term. The risk seems to remain high for 5-12 weeks after COVID-19 and then it decreases.

It is possible that a COVID-19 infection brings existing diabetes to light. Perhaps because people with COVID-19 are more likely to see their doctor and get health checks that can pick up diabetes.

Researchers are also considering if COVID-19 could be causing a new type of diabetes.

Type 2 diabetes develops slowly over time. Even type 1 diabetes can take months or years to come to light. So, it will be some time before anyone can say with certainty if COVID-19 is leading to an increase in diabetes.

Next steps

Scientist are working hard to find answers. To help them do this, they have built a database of new cases of diabetes in people with COVID-19.

The CoviDiab registry allows doctors from around the globe to upload de-identified information about people with COVID-19 and high blood glucose levels, who were not diagnosed with diabetes previously.

The registry also records information about medications that were used to treat COVID-19, in case the diabetes is an unknown side effect, also known as an adverse event.

Over time, the data will provide answers to many questions around COVID-19 and diabetes. In the meantime, if you or someone you know suspect diabetes seek medical attention immediately. A blood test can show if your blood glucose level is high and whether any further action is needed.

If you have questions or concerns about diabetes call the NDSS Helpline on 1800 637 700 to speak with a diabetes educator.

By Carolien Koreneff, CDE-RN, FADEA