In a recent study published in the latest issue of Diabetologia, researchers investigated the incidence of diabetes among coronavirus disease 2019 (COVID-19) cases.
There is scientific evidence for impaired glucose-stimulated insulin secretion following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. It most likely occurs because SARS-CoV-2 damages pancreatic β cells by triggering proinflammatory cytokines. Proinflammatory pathways cause low-quality inflammation in adipose tissue, a key player in the pathogenesis of type 2 diabetes. Subsequently, new-onset hyperglycemia and insulin resistance occurred in patients who had recovered from COVID-19.
However, it is yet unknown whether these metabolic changes are short-lived or could increase the risk of persisting diabetes in those recovering from COVID-19.
About the study
In the current retrospective cohort study, researchers screened 8.8 million patients from the Disease Analyzer (DA), a healthcare database that records a panel of 1171 physicians’ practices in Germany. Patients with acute upper respiratory tract infections (AURI) formed the control group for the study. The mean age of control group participants was 43 years, and 46% were female.
The research team used the International Classification of Diseases (ICD)-10 code for disease identification during the study. Accordingly, ICD-10 codes U07.1 and J00–J06 denoted cases of newly diagnosed COVID-19 and AURI, respectively. The two study cohorts encompassed individuals with newly diagnosed COVID-19 or AURI with index dates of the first diagnosis between 1 March 2020 and 31 January 2021. However, all type 2 diabetes cases and other forms of diabetes, or unspecified diabetes diagnosed after the index dates, were categorized under ICD-10 codes E11 and E12–E14.
The follow-up continued till July 2021 during the study, with a median of 119 days for COVID-19 and 161 days for AURI patients.
The researchers performed 1:1 propensity score matching for age, sex, health insurance, comorbidities, and index month for COVID-19. They obtained incidence rate ratios (IRRs) for new-onset diabetes using the person-years method, applying the Poisson regression models that account for varying exposure times via offsets.
There were 35,865 COVID-19 infected individuals during the study period and an equal number of AURI individuals after propensity score matching. The clinical and demographic characteristics of 35,865 AURI controls were similar to the COVID-19 group.
Overall, the study population comprised a healthier sample with milder COVID-19, requiring fewer hospitalizations (~10%) and no history of diabetes. Women constituted 52% of the 2.4 million people with COVID-19 in Germany during the study period of January 2020 to February 2021.
The number of hospital visits one year after index dates were comparable in COVID-19 and AURI groups. Likewise, the documented hospitalization cases were the same in COVID-19 and AURI cohorts during the follow-up period.
Concerning medication prescribed to the individuals in both groups, non-steroidal antirheumatics were often prescribed at index dates. However, later, while COVID-19 patients were more often prescribed povidone-iodine due to its antiviral properties against SARS-CoV-2, AURI patients were prescribed antibiotics. Furthermore, more than 50% of individuals in both COVID-19 and AURI groups were not prescribed any glucose-lowering medications when diagnosed with diabetes.
Kaplan–Meier curves for the COVID-19 group showed a substantial increase in type 2 diabetes incidences, which continued over the whole study period; however, such differences for Kaplan–Meier curves were not observed for unspecified diabetes or other forms. The authors noted increased IRRs for type 2 diabetes, but not for other forms of diabetes and unspecified diabetes.
The IRRs of type 2 diabetes in the control and the COVID-19 group were 13.6 and 20.5 per 1000 person-years, respectively; subsequently, the overall IRR was 1.51.
The first sensitivity analysis of type 2 diabetes yielded an IRR of 1.26. For the second sensitivity analysis, the researchers selected control group participants who produced SARS-CoV-2 test reports post seven days of the index date of AURI diagnosis, without being diagnosed with ICD-10 code U07.1.
The study findings revealed a temporal relationship between mild COVID-19 and newly diagnosed type 2 diabetes, thus emphasizing active monitoring of glucose dysregulation after recovering from SARS-CoV-2 infection. These findings are consistent with 29 incidences per 1000 person-years of new-onset diabetes in 47,780 COVID-19 patients reported in a retrospective cohort study of hospitalized COVID-19 patients in the UK.
To conclude, the authors strongly recommended mandatory screening of individuals who have recovered from COVID-19 for early diagnosis of new-onset diabetes. In the future, studies investigating the effects of COVID-19 on glucose and HbA1c measurements could aid in devising comprehensive treatment strategies for patients at high risk.