Type 2 Diabetes and COVID-19-Related Mortality in the Critical Care Setting: A National Cohort Study in England, March-July 2020

Abstract

Objective: To describe the relationship between type 2 diabetes and all-cause mortality among adults with coronavirus disease 2019 (COVID-19) in the critical care setting.

Research design and methods: This was a nationwide retrospective cohort study in people admitted to hospital in England with COVID-19 requiring admission to a high dependency unit (HDU) or intensive care unit (ICU) between 1 March 2020 and 27 July 2020. Cox proportional hazards models were used to estimate 30-day in-hospital all-cause mortality associated with type 2 diabetes, with adjustment for age, sex, ethnicity, obesity, and other major comorbidities (chronic respiratory disease, asthma, chronic heart disease, hypertension, immunosuppression, chronic neurological disease, chronic renal disease, and chronic liver disease).

Results: A total of 19,256 COVID-19-related HDU and ICU admissions were included in the primary analysis, including 13,809 HDU (mean age 70 years) and 5,447 ICU (mean age 58 years) admissions. Of those admitted, 3,524 (18.3%) had type 2 diabetes and 5,077 (26.4%) died during the study period. Patients with type 2 diabetes were at increased risk of death (adjusted hazard ratio [aHR] 1.23 [95% CI 1.14, 1.32]), and this result was consistent in HDU and ICU subsets. The relative mortality risk associated with type 2 diabetes decreased with higher age (age 18-49 years aHR 1.50 [95% CI 1.05, 2.15], age 50-64 years 1.29 [1.10, 1.51], and age ≥65 years 1.18 [1.09, 1.29]; P value for age-type 2 diabetes interaction = 0.002).

Conclusions: Type 2 diabetes may be an independent prognostic factor for survival in people with severe COVID-19 requiring critical care treatment, and in this setting the risk increase associated with type 2 diabetes is greatest in younger people.

Figure 1

Kaplan-Meier plots for in-hospital COVID-19 death in 19,256 patients admitted to critical care (HDU or ICU) in CHESS by time since hospital admission. Plots show the proportion of individuals at risk who were still alive at regular intervals up to 30 days from admission, stratified by the presence of type 2 diabetes. People discharged from hospital prior to 30 days were assumed to survive to 30 days and are included in the number at risk until 30 days, in keeping with the standard practice for time-to-event modeling in analysis of critical care patients.

Figure 2

Major subgroup analysis of the primary outcome of 30-day in-hospital mortality. Hazard ratios represent the mortality risk associated with the presence of type 2 diabetes in each subgroup. Bars represent 95% CIs. *Hazard ratios for other subgroups: mixed ethnicity 1.91 (95% CI 1.03, 3.56), other ethnicity 0.96 (0.67, 1.39), missing ethnicity 1.34 (1.11, 1.62), missing obesity 1.28 (1.08, 1.46).