The impact of impaired insulin regulation on severity of SARS-CoV-2 infection: a 2-year retrospective single-center analysis

BACKGROUND: The COVID-19 pandemic has caused an international healthcare crisis and produced a large healthcare burden. Diabetes mellitus (DM) is a common disease that can be controlled via pharmacologic agents; however, many patients have poor glycemic control, leading to disease-related complications. DM has been reported in the literature to be associated with increasing morbidity and mortality in COVID-19 patients. The authors aim to assess the associations between glucose homoeostasis and COVID-19 disease severity and mortality. METHODS: A retrospective chart review of patients ages 18–100 years of age admitted with COVID-19 between January 2020 and December 2021 was performed. The primary outcome was COVID-19 mortality with respect to haemoglobin A1C levels of less than 5.7%, 5.7–6.4%, and 6.5% and greater. Disease severity was determined by degree of supplemental oxygen requirements (ambient air, low-flow nasal cannula, high-flow nasal cannula, non-invasive mechanical ventilation, and invasive mechanical ventilation). COVID-19 mortality and severity were also compared to blood glucose levels on admission as grouped by less than 200 mg/dl and greater than or equal to 200 mg/dl. RESULTS: A total of 1156 patients were included in the final analysis. There was a statistically significant association between diabetic status and mortality (P=0.0002). Statistical significance was also noted between admission blood glucose ≥200 mg/dl and mortality (P=0.0058) and respiratory disease severity (P=0.0381). A multivariate logistic regression for predicting mortality showed increasing haemoglobin A1C was associated with increased mortality (odds ratio 1.72 with 95% CI of 1.122–2.635). CONCLUSIONS: In our 2-year retrospective analysis, there was an association between a diagnosis of DM and COVID-19-related mortality. Hyperglycaemia on admission was found to be statistically significant with mortality in patients diagnosed with COVID-19. Glucose homoeostasis and insulin dysregulation likely play a contributing factor to COVID-19 disease severity and mortality.