Hyperglycaemia increases mortality risk in non-diabetic patients with COVID-19 even more than in diabetic patients

Aim Diabetes has been identified as a risk factor for poor outcomes in patients with COVID-19. We examined the association of hyperglycaemia, both in the presence and absence of pre-existing diabetes, with severity and outcomes in COVID-19 patients. Methods Data from 74,148 COVID-19-positive inpatients with at least one recorded glucose measurement during their inpatient episode were analysed for presence of pre-existing diabetes diagnosis and any glucose values in the hyperglycaemic range (>180 mg/dl). Results Among patients with and without a pre-existing diabetes diagnosis on admission, mortality was substantially higher in the presence of high glucose measurements versus all measurements in the normal range (70-180 mg/dl) in both groups (non-diabetics: 21.7% vs. 3.3%; diabetics 14.4% vs. 4.3%). When adjusting for patient age, BMI, severity on admission and oxygen saturation on admission, this increased risk of mortality persisted and varied by diabetes diagnosis. Among patients with a pre-existing diabetes diagnosis, any hyperglycaemic value during the episode was associated with a substantial increase in the odds of mortality (OR: 1.77, 95% CI: 1.52-2.07); among patients without a pre-existing diabetes diagnosis, this risk nearly doubled (OR: 3.07, 95% CI: 2.79-3.37). Conclusion This retrospective analysis identified hyperglycaemia in COVID-19 patients as an independent risk factor for mortality after adjusting for the presence of diabetes and other known risk factors. This indicates that the extent of glucose control could serve as a mechanism for modifying the risk of COVID-19 morality in the inpatient environment.