Since early in the pandemic, doctors have noticed something puzzling: some people were diagnosed with diabetes during or shortly after a COVID-19 infection, with no prior history of the disease. A study from an international research registry adds to the evidence that the virus may affect how the body handles blood sugar.
How the study was done
Researchers set up a global online registry to collect cases of diabetes newly diagnosed in people with COVID-19. The study was posted as a preprint on Research Square, meaning it hadn’t yet completed peer review when it was released.
The team gathered clinical and lab data from 537 patients at 61 hospitals in 25 countries between 2020 and 2022. All were diagnosed with diabetes within four weeks of a COVID-19 infection, and none had a known history of diabetes or had used glucose-lowering medicines before.
What the researchers found
- Most cases looked like type 2 diabetes. The majority of patients whose type could be classified had type 2, the form linked to insulin resistance.
- Some cases didn’t fit a clear category. A large share of patients had diabetes that couldn’t yet be classified as type 1 or type 2.
- A few children developed type 1 diabetes.
- Diabetes often lasted beyond the infection. Among patients with follow-up data, many still had diabetes after recovering from COVID-19.
The researchers wrote that the study shows “clinical plausibility” for COVID-19 affecting blood sugar regulation, and they suggested screening for diabetes in people who’ve had the infection, particularly severe illness.
Cause, or earlier detection?
An important caveat is that the researchers couldn’t tell whether the virus actually caused new diabetes or whether the infection simply revealed diabetes that was already developing. People who are hospitalized get blood tests they might otherwise never have had. Severe illness and some treatments, such as steroids, can also raise blood sugar temporarily.
Still, there are reasons to think the virus might play a direct role. The coronavirus can infect many tissues, and researchers have proposed that it could affect the pancreas, where insulin is made, or worsen insulin resistance through widespread inflammation. Other studies, including a large analysis of U.S. veterans published in 2022, have found a higher risk of new diabetes in the months after COVID-19.
Who should pay attention
The link appears most relevant for people who had moderate or severe COVID-19, and for those who already had risk factors for type 2 diabetes, such as excess weight, a family history, high blood pressure or prediabetes.
What this means for you
- Know the signs of high blood sugar. Extreme thirst, frequent urination, fatigue, blurry vision and unexplained weight loss are worth reporting to your doctor.
- Ask about screening. If you had a significant COVID-19 illness or have other diabetes risk factors, ask whether an A1C or fasting glucose test makes sense.
- Follow up after a hospital stay. If your blood sugar was high while you were sick, make sure it’s rechecked once you’ve recovered.
- Lower your risk of severe infection. Staying up to date on recommended COVID-19 vaccines reduces the chance of serious illness.
- Keep up healthy habits. Regular activity, balanced meals and good sleep all support healthy blood sugar.
The bottom line
A global registry found hundreds of cases of diabetes diagnosed soon after COVID-19, many of which persisted. It’s not yet clear whether the virus causes diabetes or unmasks it, but the findings support checking blood sugar after a serious infection, especially if you have other risk factors.
This article is for general information and isn’t medical advice. Talk with your healthcare provider about your individual needs.
