Glucose-lowering drugs and outcome from COVID-19 among patients with type 2 diabetes mellitus: a population-wide analysis in Hong Kong

OBJECTIVES: To investigate the association between baseline use of glucose-lowering drugs and serious clinical outcome among patients with type 2 diabetes. DESIGN: Territory-wide retrospective cohort of confirmed cases of COVID-19 between January 2020 and February 2021. SETTING: All public health facilities in Hong Kong. PARTICIPANTS: 1220 patients with diabetes who were admitted for confirmed COVID-19. PRIMARY AND SECONDARY OUTCOME MEASURES: Composite clinical endpoint of intensive care unit admission, requirement of invasive mechanical ventilation and/or in-hospital death. RESULTS: In this cohort (median age 65.3 years, 54.3% men), 737 (60.4%) patients were treated with metformin, 385 (31.6%) with sulphonylureas, 199 (16.3%) with dipeptidyl peptidase-4 (DPP-4) inhibitors and 273 (22.4%) with insulin prior to admission. In multivariate Cox regression, use of metformin and DPP-4 inhibitors was associated with reduced incidence of the composite endpoint relative to non-use, with respective HRs of 0.51 (95% CI 0.34 to 0.77, p=0.001) and 0.46 (95% CI 0.29 to 0.71, p<0.001), adjusted for age, sex, diabetes duration, glycated haemoglobin (HbA1c), smoking, comorbidities and drugs. Use of sulphonylureas (HR 1.55, 95% CI 1.07 to 2.24, p=0.022) and insulin (HR 6.34, 95% CI 3.72 to 10.78, p<0.001) were both associated with increased hazards of the composite endpoint. CONCLUSIONS: Users of metformin and DPP-4 inhibitors had fewer adverse outcomes from COVID-19 compared with non-users, whereas insulin and sulphonylurea might predict a worse prognosis.