ABSTRACT
Aim: Diabetes has consistently been shown to increase the risk of poor covid-19 outcomes. Rather than a simple additive effect of diabetes and age-related risk, recent studies suggest a disproportionately higher relative mortality risk in younger people. Better understanding the interaction between age and diabetes could help inform complex prioritisation decisions around covid-19 vaccination. Methods: We triangulate evidence on heterogeneity of diabetes effect by age on covid-19 mortality from large UK studies. Two population-based studies (OpenSAFELY [n = 17,278,392, 8.8% diabetes] and QCOVID [n = 6,083,102, 7.0% diabetes]), report age-specific hazard ratios (HR) associated with diabetes for covid-19 mortality. We also examine age-specific HRs in severe covid-19 (n = 19,256 critical care patients in England, 18.3% diabetes). To aid interpretability, we translate risk estimates into covid-age;the additional years of covid-19 mortality risk added to an individual's chronological age if diabetes is present. Results: Additional covid-19 mortality risk associated with diabetes is markedly higher in younger than older people across all studies. This reflects the higher relative risk associated with diabetes in younger age groups (HRs for diabetes >5 in ages <50 in OpenSAFELY and QCOVID). For a person aged 40 with diabetes, additional mortality risk is equivalent to 20 years of chronological age, meaning risk is similar to that of a person without diabetes aged 60. For a person aged 70 with diabetes, additional mortality risk from diabetes is equivalent to an additional 5 years, so their covid age is 75. Conclusion: The disproportionate covid-19 mortality risk in younger people with diabetes should be considered to ensure they are appropriately prioritised for vaccination.