Liu L, Wei W, Yang K, et al. - Researchers conducted this retrospective study to investigate the connection between glycemic control before admission with severity and mortality of coronavirus disease 2019, and tried to reveal the mechanism. In total, 77 inpatients were grouped into sufficient control group (glycated hemoglobin [HbA1c] < 6.5%, n = 49) and insufficient control group (HbA1c ≥ 6.5%, n = 28). Compared with patients with HbA1c < 6.5, patients with HbA1c ≥ 6.5 exhibited higher heart rate, lower percutaneous oxygen saturation, higher levels of multiple indicators of inflammation like white blood cell count, neutrophil count, high-sensitivity C-reactive protein, and serum ferritin, as well as lower levels of lymphocyte count at hospital admission. HbA1c was found to be an independent risk factor for poor outcomes in patients with coronavirus disease 2019. Severe pulmonary infection and the resulting acute respiratory distress syndrome may be the primary causes of death in patients with insufficient glycemic control.