Study explores the risk of new-onset diabetes mellitus following SARS-CoV-2 infections

In a recent study posted to the medRxiv* preprint server, researchers evaluated individuals who had severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and were diagnosed with diabetes mellitus within six months of the onset of coronavirus disease 2019 (COVID-19) to understand the temporal relationship between SARS-CoV-2 infections and diabetes mellitus.

Background

Recent research indicates a potential increase in the new-onset diabetes mellitus diagnoses after SARS-CoV-2 infections. While the causative mechanisms are not clearly understood, various hypotheses suggest the roles of stress-induced hyperglycemia during SARS-CoV-2 infections, changes in the innate immune system, virus-induced damage or changes to the beta cells or vasculature of the pancreas, as well as the side effects of the treatment in the increased incidence of diabetes mellitus diagnoses.

Furthermore, the drastic lifestyle changes brought about by the COVID-19 pandemic have decreased physical activity and increased obesity. The stress induced by the pandemic has also increased endogenous cortisol levels, a known risk factor for diabetes mellitus. Examining the temporal relationship between SARS-CoV-2 infections and new-onset cases of diabetes mellitus will help develop effective screening and therapeutic strategies.

About the study

In the present study, the team conducted a nationwide analysis using electronic health records aggregated in the National COVID Cohort Collaborative (N3C) database in the United States (U.S.). They analyzed all individuals with SARS-CoV-2 infections and type 2 diabetes mellitus between March 2020 and February 2022. Data from the health records for the six months preceding and following the SARS-CoV-2 infections were included to avoid selection and ascertainment bias.

SARS-CoV-2 infections were confirmed based on the International Classification of Diseases, Tenth Revision (ICD-10) code, or laboratory test results. New-onset diabetes mellitus cases were defined as those that did not have an ICD code for diabetes mellitus in their electronic health records before September 2019. The incidence of diabetes mellitus was then analyzed concerning SARS-CoV-2 infections.

Results

The results reported a sharp increase in new-onset diabetes mellitus diagnoses in the 30 days following SARS-CoV-2 infections, with the incidence of new diagnoses decreasing in the post-acute stage up to approximately a year after the infection. Surprisingly, the number of new-onset diabetes mellitus cases in the months following SARS-CoV-2 infections is lower than in the months preceding the infection.

The authors believe that the increase in healthcare interactions brought about due to the COVID-19 pandemic might explain the notable increase in diabetes mellitus diagnoses in the time surrounding SARS-CoV-2 infections. New patients might have been tested for hemoglobin A1C or glucose levels during their first interaction with the healthcare system, the results of which might have then been used to diagnose diabetes mellitus.

Additionally, SARS-CoV-2 infection-induced physiological stress could have triggered diabetes mellitus in high-risk individuals who might have developed the disease later in life without COVID-19.

According to the authors, the overall risk of developing diabetes mellitus has increased, irrespective of SARS-CoV-2 infections, due to the drastic decrease in physical activity, weight gain, and the stress induced by the COVID-19 pandemic. Furthermore, a longer follow-up period might report an increased incidence in new-onset diabetes mellitus cases, with the SARS-CoV-2 infection precipitating disease development in individuals who might not have otherwise developed diabetes.

Conclusions

To summarize, the researchers conducted a cross-sectional, nationwide analysis of individuals in the U.S. to understand the temporal relationship between diagnoses of new-onset diabetes mellitus and SARS-CoV-2 infections. The results reported a spike in diabetes mellitus diagnoses in the one month following SARS-CoV-2 infections, followed by a marked decrease in the number of diagnoses for up to a year after the infection.

The authors believe that the sudden increase in diabetes diagnoses could be due to increased healthcare interactions brought about by the COVID-19 pandemic. The new-onset diabetes mellitus cases could also be a reaction to the physiological stress induced by SARS-CoV-2 infections.

Furthermore, the drastic lifestyle changes brought about by the COVID-19 pandemic might be responsible for the high incidence of diabetes mellitus, irrespective of SARS-CoV-2 infections. However, extensive research is required to understand the epidemiology and mechanisms connecting SARS-CoV-2 infections with new-onset diabetes mellitus.

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Written by

Dr. Chinta Sidharthan

Chinta Sidharthan is a writer based in Bangalore, India. Her academic background is in evolutionary biology and genetics, and she has extensive experience in scientific research, teaching, science writing, and herpetology. Chinta holds a Ph.D. in evolutionary biology from the Indian Institute of Science and is passionate about science education, writing, animals, wildlife, and conservation. For her doctoral research, she explored the origins and diversification of blindsnakes in India, as a part of which she did extensive fieldwork in the jungles of southern India. She has received the Canadian Governor General’s bronze medal and Bangalore University gold medal for academic excellence and published her research in high-impact journals.