Both high and low pre-infection glucose levels associated with increased risk for severe COVID-19: New insights from a population-based study.

Importance: Patients with diabetes are known to be at increased risk for infections including severe coronavirus disease 2019 (COVID-19) but the relationship between COVID-19 severity and specific pre-infection glucose levels is not known.

Objective: To assess the differential effects of pre-infection glucose levels on the risk for severe COVID-19 amongst patients with and without diabetes.

Design: Population based historical cohort study.