Patients with COVID-19 were found to be at a higher risk of developing type 2 diabetes, with unvaccinated individuals experiencing an 8.76-fold higher incidence compared to their vaccinated counterparts, according to a recent study.
The new findings translate into approximately 8,700 additional new cases of type 2 diabetes in England in the 6 months following COVID-19 infection over the study period. The estimate took into account non-vaccination rates and hospitalization data.
The retrospective cohort study comprised of 16 million individuals. Researchers focused on type 1, type 2, gestational, and non-specific diabetes over a period of 52 weeks post-COVID-19 diagnosis.
The study, published in The Lancet Diabetes & Endocrinology, used linked electronic health records to analyze data from three cohorts: pre-vaccination, vaccinated, and unvaccinated individuals aged 18 to 110 years. Adjusted hazard ratios (aHRs) were computed to compare diabetes incidence before and after COVID-19 diagnosis, stratified by severity of COVID-19 and type of diabetes.
In the pre-vaccination cohort (n = 16,669,943), the incidence of type 2 diabetes increased post-COVID-19, with aHRs decreasing from 4.3 during weeks 1 to 4 to 1.24 during weeks 53 to 102. Unvaccinated individuals had higher aHRs (8.76) compared to vaccinated individuals (1.66) within the first 4 weeks. The highest aHRs for type 2 diabetes were observed among hospitalized COVID-19 patients, with an aHR of 28.3 during weeks 1 to 4, decreasing to 2.04 by weeks 53 to102. For patients who were not hospitalized, the aHRs were 1.95 during the first 4 weeks, decreasing to 1.11 during weeks 53 to 102.
Unvaccinated individuals tended to be younger, with 61.1% being 40 years old or younger, more often male (58.2%), and had higher proportions of South Asian (9.6%) and Black (5.2%) ethnic backgrounds compared to the vaccinated group. Around 60% of type 2 diabetes cases continued for at least 4 months after COVID-19, characterized by ongoing treatment with 2 or more glucose-lowering medication prescriptions or elevated HbA1c levels (≥47.5 mmol/mol).
The aHRs for type 1 diabetes were elevated during the first year after COVID-19 infection but did not remain high beyond that period. For instance, in the pre-vaccination group, the aHR was 2.27 within the first 4 weeks. Type 2 diabetes persisted for 4 months in approximately 60% of cases diagnosed post-COVID-19. While type 1 diabetes showed a similar initial increase, the excess incidence did not persist beyond one year.
There was no clear increase in the risk of gestational diabetes following COVID-19 infection. However, there was some indication of small increases in the incidence of other forms of diabetes that persisted beyond 9 months.
The study used data up to December 14, 2021, before the omicron variant became dominant in England. The researchers noted some limitations, including potential under ascertainment of mild or asymptomatic COVID-19 cases early in the pandemic when widespread testing was not available.
Full disclosures can be found in the published study.
