Severe COVID-19 Linked to New Diabetes Diagnoses

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April 19, 2023 – COVID can more than triple the chance of being diagnosed with type 2 diabetes within a year of being infected, according to a new Canadian study.

Men who had even a mild case of COVID were significantly more likely than non-infected men to be diagnosed with type 2 diabetes, which is a chronic condition that affects how the body turns food into energy. Women didn’t have an increased risk unless they were severely ill.

Both men and women who had severe cases were at the highest risk. People who were hospitalized for COVID treatment had more than a doubled risk of being diagnosed with type 2 diabetes, and those who were admitted to intensive care units had more than a tripled risk.

“This is definitely a concern in terms of long-term outcomes,” researcher and University of British Columbia professor Naveed Z. Janjua, PhD, told The New York Times. “With a respiratory infection, you usually think, ‘Seven or eight days and I’m done with it, that’s it.’ [But] here we’re seeing lingering effects that are lifelong.”

The study was published on Tuesday  in JAMA Network Open. Researchers analyzed health data from 2020 and 2021 for 629,935 people, 20% of whom were diagnosed with COVID during that time. Most people in the study had not been vaccinated because vaccines were not widely available then. The health information came from a registry maintained by public health officials in British Columbia, Canada. The follow-up period was 257 days.

The authors cautioned that their findings could not say that COVID causes type 2 diabetes; rather, in a commentary published along with the study, Pamela B. Davis, MD, PhD, said the link makes sense because COVID is known to impact the pancreas, which makes insulin. Insulin is a hormone that helps the body regulate blood sugar -- a process that doesn’t work properly in people with diabetes. 

“Such a stress may move a patient from a prediabetic state into diabetes,” wrote Davis, who is a former dean of the Case Western University School of Medicine in Ohio, where she is now a professor. 

The researchers estimated that the increased pattern of diagnoses of diabetes following COVID infection could increase the rate of the disease occurring in the general population by 3% to 5% overall.