COVID-19 infection increases risk of developing diabetes, study finds

COVID-19 survivors are at increased risk of being newly diagnosed with diabetes up to one year after recovering, a new study suggests.

Researchers from VA Saint Louis Health Care System found people who recovered from COVID were 40% more likely to develop a new case of diabetes compared to a control group.

This translates to 1 in 100 people at increased risk of developing diabetes after a COVID-19 infection. As of Monday, 79.5 million people have been infected with COVID-19 in the U.S., according to the Centers for Disease Control and Prevention, meaning there could 795,000 new diabetes diagnosis as a result.

"That's hard for me to swallow," Dr. Ziyad Al-Aly, chief of research and development at VA Saint Louis Health Care System, and lead author of the study, told ABC News. "COVID-19 isn't only about the acute effects. This is going to leave a lot of people with long-term health consequences that they'll have to deal with for a lifetime and that's jarring. It's unsettling to accept."

For the study, published Monday in the journal Lancet Diabetes & Endocrinology, the team looked at patient data from the U.S. Department of Veterans Affairs between March 1, 2020 and Sept. 30, 2021.

They compared more than 181,000 patients who had tested positive for COVID-19 to more than 4.1 million patients who were not infected over the same period. The data was also compared to another 4.28 million patients who were treated at the VA in 2018 and 2019.

Al-Aly said the team initially thought the increased risk would only be seen among people who have risk factors for diabetes such as obesity, but the findings showed the risk was evident across all groups.

"It was evident in Black people and white people; it was evident in young folks and in older folks; it was evident in males and females; and, most importantly, it was also evident even in people who had no risk factors for diabetes at all," he said.

He added that there are a few theories of how COVID increases the risk for diabetes, although none have been proven or refuted.

One theory is that COVID-19 drives inflammation that may impair insulin secretion and sensitivity. Another is that COVID-19 causes disturbances in microbiome composition and function, that may lead to diabetes.

The findings add to a growing body of evidence that COVID-19 infection can lead to long-term health consequences.

Al-Aly said when most people think of long-lasting health effects following COVID, they think of shortness of breath, difficulty concentrating and sleep disorders.

But more and more studies have shown COVID survivors can suffer from heart problems, kidney problems and, in this case, diabetes.

"Over the past year or so, we started noticing in some patients that those [long-term] manifestations are not just fatigue and brain fog, but people are coming down with new onset diabetes," he said.

Of the patients who did develop diabetes more than 99% developed type 2 diabetes, which is the most common form of diabetes and occurs when cells become resistant to insulin -- the hormone that regulates blood sugar,

Because of insulin resistance, the pancreas must make more insulin to try to get cells to respond and this leads to high blood sugar levels.

This is different from type 1 diabetes, which is usually diagnosed in children and teens, and occurs when the pancreas doesn't make insulin or makes very little insulin.

The new study is not the first that has linked COVID-19 infection to diabetes.

In a study published last week, researchers from the Leibniz Center for Diabetes Research at Heinrich Heine University in Düsseldorf, Germany, found a 28% increased risk of type 2 diabetes for those who had previously had COVID-19.

Al-Aly said the best way to lower the risk of diabetes is for people to prevent themselves from getting COVID-19 in the first place via vaccination.

But for people who have already caught the virus, they should watch for warning signs of diabetes such as excessive thirst and frequent urination.

"Those are signs of diabetes, and we need you to get checked because catching this early and identifying diabetes early and treating it, or nipping it in the bud, is always better than leaving it unattended for years and suffering even worse or more serious health consequences," Al-Aly said.