Comparative incidence of diabetes following hospital admission for COVID-19 and pneumonia: a cohort study

Objective: The incidence of diabetes may be elevated following COVID-19 but it is unclear whether this is specific to SARS-CoV-2 infection, associated with shared risk factors for severe COVID-19 and diabetes and/or a generic risk following illness. Research design and methods: People admitted to hospital for COVID-19 and/or pneumonia between 1st April 2020 and 31st August 2020 in England were linked with the National Diabetes Audit to identify incident diabetes post discharge up to 31st March 2021. Comparator cohorts admitted with pneumonia over the same dates in 2017, 2018 and 2019 were followed until 31st March 2018, 31st March 2019 and 31st March 2020 respectively. Poisson regression models were used to calculate adjusted diabetes incidence rates. Results: Using the cohort of people discharged from hospital following a diagnosis of COVID-19 without pneumonia in 2020 as the standard population (incidence rate 16.4 per 1000 person-years (95% CI 12.8-20.7), adjusting for age, sex, ethnicity and deprivation gave incidence rates of 19.0 (95% CI 13.8-25.6) and 16.6 (95% CI 13.3-20.4) per 1000 person-years for those admitted for COVID-19 with pneumonia and pneumonia without COVID-19 in 2020. These rates are not significantly different from those found after hospital admission for pneumonia in 2019, 2018 and 2017 (13.7 (95% CI 10.8-17.3), (13.8 (95% CI 10.9-17.4), 14.2 (95% CI 10.9-18.3) per 1000 person-years respectively). Conclusions: Our data do not support a clear impact of COVID-19 on the incidence of diabetes compared to risks in several comparators groups including contemporaneously assessed risks in people hospitalised with pneumonia.