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Associations of type 1 and type 2 diabetes with COVID-19-related mortality in England: a whole-population study

Our take —

This population-based cohort study of more than 61 million people in England demonstrated that one third of in-hospital COVID-19 deaths between March 1 and May 11, 2020 were among people with diabetes, and that the odds of in-hospital death from COVID-19 were 2.9 and 1.8 times higher among those with Type 1 and Type 2 diabetes, respectively, relative to those without diabetes, independent of sociodemographic factors and cardiovascular comorbidities. Although the analyses excluded the significant proportion of COVID-19-related deaths occurring in nursing home settings and did not adjust for known confounders like BMI and high blood pressure, they nevertheless provide among the strongest evidence to date on the absolute and relative risks of COVID-19 mortality among people with diabetes in a high-income country with universal health care.

Study design

Prospective Cohort

Study population and setting

This national population-based study evaluated the association between diabetes (Type 1, Type 2, and other types) and in-hospital death from COVID-19 in England from March 1 to May 11, 2020. Data were ascertained through the linkage of four National Health Services (NHS) electronic health records datasets, including the COVID-19 Patient Notification System. The study sample included 61,414,470 people (mean age 41 years [standard deviation (SD) 23]; 50% female) who were alive on February 16, 2020 and registered with a general practice in England, nearly the total population.

Summary of Main Findings

The prevalence of Type 1 diabetes in the population was 0.4% (n=263,830; mean age 47 years [SD 20]; 43% female), the prevalence of Type 2 diabetes was 4.7% (n=2,864,670; mean age= 67 years [SD 13]; 44% female), and 0.1% had other types of diabetes (n=41,750; mean age 39.5 years [SD 23]; 46% female). By May 11, 2020, 23,698 people with COVID-19 had died in hospitals in England, of whom 31% had type 2,1.5% had Type 1 diabetes, and 0.1% had other types of diabetes. Compared to those without documented diabetes, the odds of death from COVID-19 was 2.9 times higher for those with Type 1 diabetes (aOR=2.86; 95% CI: 2.58-3.18 ) and 1.8 times higher for those with Type 2 diabetes (aOR= 1.80; 95% CI 1.75-1.86), independent of age, sex, socioeconomic status, ethnicity, region, and significant CVD comorbidities (coronary heart disease, cerebrovascular disease, and heart failure).

Study Strengths

This study utilized NHS data, providing a study sample size of more than 61 million and including nearly the entire national population. This large sample provided the power to estimate COVID-19 mortality risk associated with diabetes by type and among population subgroups.

Limitations

COVID-19-related deaths in nursing homes were not counted as outcomes in this study and given the higher proportion of people with diabetes in these settings, their exclusion may underestimate the relative odds of death associated with diabetes. Conversely, the associations reported between diabetes and COVID-19 mortality may be overestimated because the multivariable analyses did not adjust for several potential differences known to be positively associated with both COVID-19 mortality and diabetes, such as body mass index, high blood pressure, tobacco smoking, and kidney disease. Because the denominator for estimates was the total population rather than cases or infections, the estimates may reflect both differential risks of infection and risks of death.

Value added

Though several studies have identified diabetes as a risk factor for COVID-19 severity and mortality, this is the first study to assess risks separately for Type 1 and Type 2 diabetes, and to quantify absolute and relative risks of in-hospital COVID-19 mortality by diabetes type for England overall, and within specific age, sex, and racial/ethnic sub-populations.

This review was posted on: 28 August 2020