Associations between reductions in routine care delivery and non-COVID-19-related mortality in people with diabetes in England during the COVID-19 pandemic: a population-based parallel cohort study

Background: The Office for Health Improvement and Disparities, part of the UK Government Department of Health and Social Care, highlighted an emerging signal of increased non-COVID-19-related deaths in England between July and October, 2021, with a potentially disproportionate higher increase in people with diabetes. We aimed to substantiate and quantify this apparent excess mortality, and to investigate the association between diabetes routine care delivery and non-COVID-19-related-mortality in people with diabetes before and after the onset of the pandemic. Methods: In this population-based parallel cohort study, we used the National Diabetes Audit (NDA) to identify people with diabetes in England. The primary outcome was non-COVID-19-related deaths between July 3, 2021, and Oct 15, 2021, in participants in the 2021 COVID-19 cohort (registered in the NDA in the periods Jan 1, 2019, to March 31, 2020, and Jan 1, 2020, to March 31, 2021) compared with deaths between June 29, 2019, and Oct 11, 2019 (the equivalent 15-week period in 2019) in the 2019 pre-COVID-19 comparator cohort (people registered in the NDA in the periods Jan 1, 2017, to March 31, 2018, and Jan 1, 2018 to March 31, 2019). In each cohort, multivariable logistic regression examined whether completion of eight diabetes care processes in each of the two years before the index mortality year was associated with non-COVID-19-related death, adjusting for diabetes type, age, sex, ethnicity, and socioeconomic deprivation. Findings: There were 3 218 570 people in the 2021 cohort and 2 973 645 people in the 2019 comparator cohort. In the 2021 cohort, there were 30 118 non-COVID-19-related deaths in people with diabetes, compared with 27 132 in the comparator cohort, representing an 11% increase (95% CI 9–13). The unadjusted incidence rate ratio (IRR) for mortality in the 2021 cohort compared to the 2019 cohort was 1·026 (1·009–1·043; p=0·003), which was unchanged after adjustment for age, sex, ethnicity, socioeconomic deprivation, and diabetes type (IRR 1·023 (1·006–1·040); p=0·007). In the 2021 cohort, 853 660 (26·5%) people received all eight care processes in 2020–21 compared with 1 547 240 (48·1%) people in 2019–20; a 44·8% (95% CI 44·7–45·0) relative reduction. In the pre-COVID-19 comparator cohort, 1 370 315 (46·1%) people with diabetes received all eight care processes in 2018–19 compared with 1 437 740 (48·3%) in 2017–18; a 4·7% (95% CI 4·5–4·9) relative decrease. Non-COVID-19-related mortality in the 2021 cohort was highest in people who did not receive all eight care processes in either of the two previous years (OR 2·67 [95% CI 2·56–2·77]; p<0·001) compared with those who received all eight care processes in both previous years. Mortality was also significantly higher in those who received all eight care processes in 2019–20 but not in 2020–21 (OR 1·66 [95% CI 1·59–1·73]; p<0·001) or not in 2019–20 but in 2020–21 (OR 1·27 [1·20–1·35]; p<0·001). This pattern of association was similar in the 2019 pre-COVID-19 cohort. Interpretation: Our results show an increased risk of mortality in those who did not receive all eight care processes in one or both of the previous two years. Our results provide evidence that the increased rate of non-COVID-19-related mortality in people with diabetes in England observed between July 3, and Oct 15 of 2021 is associated with a reduction in completion of routine diabetes care processes following the pandemic onset in 2020