Abstract: Medicine ® Observational Study Blood glucose control with different treatment regimens in type 2 diabetes patients hospitalized with COVID-19 infection A retrospective study Elena Chertok Shacham, MDa,* , Nimra Maman, BSb, Avraham Ishay, MDa,c Abstract Coronavirus disease (COVID-19) is closely associated with hyperglycemia and a worse prognosis in patients with a previous diagnosis of type 2 diabetes mellitus. A few studies investigated the effects of diabetes treatment regimens in these patients during hospitalization. Here, we evaluate the impact of insulin and non-insulin therapy on glucose control in patients with type 2 diabetes admitted with COVID-19. This is a retrospective study including 359 COVID-19 patients with type 2 diabetes. Patients were divided into 2 groups according to diabetes treatment during hospitalization. The first group included patients treated with insulin only, and the second group patients treated with other antidiabetic agents with or without insulin. Average blood glucose was higher in the insulin-only treatment group (201 ± 66 mg/dL vs 180 ± 71 mg/dL, P = .004), even after excluding mechanically ventilated patients (192 ± 69 vs 169 ± 59 mg/dL, P = .003). In patients with moderate severity of COVID-19, average blood glucose was also significantly higher in the insulin-only treated group (197 ± 76 vs 168 ± 51 mg/dL, P = .001). Most patients (80%) in the combination treatment group received metformin. Moderately affected COVID-19 patients with type 2 diabetes could safely be treated with antihyperglycemic medications with or without insulin. Abbreviations: GLP-1 RA = glucagon-like peptide-1 receptor agonists, HbA1c = hemoglobin A1c, SGLT-2 = sodium-glucose transport protein. Keywords: COVID-19, diabetes therapy in the hospital, type 2 diabetes hospitalized, the mortality rate was 28.8% in patients with diabetes and/or uncontrolled hyperglycemia compared with 6.2% in patients with normoglycemia.[9] In another retrospective study of >7000 COVID-19 patients, the authors noticed that in COVID-19 patients with preexisting diabetes, well-controlled blood glucose was correlated with reduced risk of allcause mortality and less frequent complications, including adult respiratory distress syndrome, acute kidney injury, and septic shock.[10] Hyperglycemia can trigger endothelial damage, and over-inflammation via an increase in the expression of cytokines, including interleukin-6 and tumor necrosis factor-α in severely ill COVID-19 patients.[11] Recent studies showed that patients with uncontrolled type 2 diabetes had reduced titers of COVID-19 neutralizing antibodies after severe acute respiratory syndrome coronavirus 2 vaccination and higher rates of breakthrough COVID-19 infection one year after vaccination.[12,13] Insulin is well-established as the most appropriate pharmacologic agent for effectively controlling glycemia in hospitals, particularly in critically ill patients.[14] Insulin regimens that