Risks of and risk factors for COVID-19 disease in people with diabetes: a cohort study of the total population of Scotland

Stuart J. McGurnaghan, Amanda Weir, Jen Bishop, Sharon Kennedy, Luke A.K . Blackbourn, David McAllister, Sharon Hutchinson, Thomas M. Caparrotta, Joseph Mellor, Anita Jeyam, Joseph E. O’Reilly, Sarah Wild, Sara Hatam, Andreas Höhn, Marco Colombo, Chris Robertson, Nazir Lone, Janet Murray, Elaine Butterly, John PetrieBrian Kennon, Rory McCrimmon, Robert Lindsay, Ewan Pearson, Naveed Satta, John McKnight, Sam Philip, Andrew Collier, Jim McMenamin, Alison Smith-Palmer, David Goldberg, Paul M. McKeigue, Helen M. Colhoun, Public Health Scotland COVID-19 Health Protection Study Group, Scottish Diabetes Research Network Epidemiology Group

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Background: The objectives were to i) ascertain the cumulative risk of fatal or CCU treated COVID-19 in those with diabetes and compare it to those without diabetes ii) among those with diabetes to investigate risk factors for, and build a cross-validated predictive model of, fatal or CCU treated COVID-19.Methods: In the total population of Scotland we ascertained all persons who had developed fatal or critical care unit-treated COVID-19 (hereafter F/CCU-COVID-19) between 1st March and July 31st 2020 from the nationwide virology, critical care unit, hospital discharge and register of deaths databases. Among those with F/CCU-COVID-19, diabetes status was ascertained by linkage to the national diabetes register. The cumulative incidence of F/CCU- COVID-19 in those with and without diabetes was compared using logistic regression. Among those with diabetes, data on potential risk factors for F/CCU-COVID-19 were obtained from diabetes register and other linked health administrative databases. Among those with diabetes we tested association of these factors with F/CCU-COVID-19 and constructed a prediction model using stepwise regression and 20-fold cross-validation.Findings: 1082 (0.3%) of all those with diabetes in Scotland (n=319 349) developed F/CCU-COVID-19; the age and sex adjusted odds ratio was [OR] 1.395 95% CI: 1.304-1.494, p<0.001 overall compared to the risk in total population of Scotland without diabetes (n=4081 cases in 5 143 951 persons). The OR was 2.396 (1.815-3.163) in type 1 and 1.369 (1.276-1.468) in type 2 diabetes. Of the 1082 persons with diabetes who developed F/CCU-COVID- 19, 90% were ≥60 years old. Among those with diabetes, adjusted for age, sex, diabetes duration and diabetes type, those who developed F/CCU-COVID-19 were more likely to be male, live in residential care, or live in a more deprived area, have a condition already listed as a COVID-19 risk condition such as heart or lung disease, have retinopathy or reduced renal function, have worse glycaemic control, have a prior diabetic ketoacidosis or hypoglycaemia hospitalisation in the past five years, be on more diabetes and other type of drugs, and to have been a smoker (all p<0.001). Those with F/CCU-COVID-19 were less likely to be on an antihypertensive and had lower systolic blood pressure than those without F/CCU-COVID-19 (both p<0.001). The relationship with BMI was J-Shaped. The cross-validated predictive model of F/CCU-COVID-19 in those with diabetes, retained 11 factors in addition to age, sex, diabetes type and duration and had a C-statistic of 0.85 (95% CI 0.83,0.86).Interpretation: Overall risks of F/CCU-COVID-19 are substantially elevated in those with type 1 and type 2 diabetes compared to the background population. The risk of F/CCU-COVID-19, and therefore the need for special protective measures, varies widely among those with diabetes but can be predicted reasonably well using prior clinical history.Funding: none
Original languageEnglish
Number of pages12
JournalThe Lancet Diabetes & Endocrinology
Early online date23 Dec 2020
Publication statusE-pub ahead of print - 23 Dec 2020


  • Covid-19
  • diabetes
  • Scotland

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