Diabetes, glycaemic control, and risk of COVID-19 hospitalisation: Population-based, prospective cohort study

OBJECTIVE: We aimed to examine the prospective association of diabetes and glycaemic control with COVID-19 hospitalisation in a large community-based cohort study. METHODS AND STUDY DESIGN: Participants (N = 337,802, aged 56.4 ± 8.1 yr; 55.1% women) underwent biomedical assessments at baseline as part of the UK Biobank prospective cohort study. The outcome was cases of COVID-19 serious enough to warrant a hospital admission from 16-March-2020 to 26-April-2020. RESULTS: At follow up, 649 cases COVID-19 were recorded. In multivariable adjusted analyses, risk of COVID-19 was elevated in people with undiagnosed diabetes at baseline (A1C ≥ 6.5%) (risk ratio = 2.68; 95% confidence interval: 1.66, 4.33) and poorly controlled (A1C ≥ 8.6%) diagnosed diabetes (1.91;1.04, 3.52). There was a dose-dependent increase in risk of COVID-19 with increasing A1C, that persisted in multivariable adjusted models (per SD [0.9%]: 1.07; 1.03, 1.11; p[trend] < 0.001). CONCLUSION: In this large community-based sample, higher levels of A1C within the normal range were a risk factor for COVID-19. Glucose regulation may play a key role in immune responses to this infection. Undiagnosed cases of diabetes in the general community may present a particularly high risk.