Previous study reported that preadmission insulin treatment in patients with coronavirus disease 2019 (COVID-19) and concurrent diabetes was associated with a significantly increased odds of mortality. However, such association may be modified by possible baseline differences in glycemic control between insulin users and non-insulin users. Misinterpretation of the association between insulin treatment and mortality could lead to confusion in clinical practice and hospitalized patients with COVID-19 for whom insulin treatment is appropriately indicated may be omitted from such treatment. However, requirement for insulin during hospitalization for COVID-19 may be a marker of poor prognosis and as such could be used to identify patient population who require more aggressive treatments to prevent mortality.