Abstract: TYPE Original Research PUBLISHED 09 November 2022 DOI 10.3389/fendo.2022.1002834 OPEN ACCESS EDITED BY Åke Sjöholm, Gävle Hospital, Sweden REVIEWED BY Fahad Aljuraibah, King Saud bin Abdulaziz University for Health Sciences, Saudi Arabia Wenfang Xia, Huazhong University of Science and Technology, China Metformin use and mortality and length of stay among hospitalized patients with type 2 diabetes and COVID-19: A multiracial, multiethnic, urban observational study *CORRESPONDENCE Claudene J. George clgeorge@montefiore.org † These authors have contributed equally to this work and share first authorship SPECIALTY SECTION This article was submitted to Clinical Diabetes, a section of the journal Frontiers in Endocrinology RECEIVED 25 July 2022 ACCEPTED 21 October 2022 PUBLISHED 09 November 2022 CITATION Miao E, Zhang K, Liu J, Lin J, Yoo D and George CJ (2022) Metformin use and mortality and length of stay among hospitalized patients with type 2 diabetes and COVID-19: A multiracial, multiethnic, urban observational study. Front. Endocrinol. 13:1002834. doi: 10.3389/fendo.2022.1002834 COPYRIGHT © 2022 Miao, Zhang, Liu, Lin, Yoo and George. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Frontiers in Endocrinology Emily Miao 1†, Kaleena Zhang 1†, Jianyou Liu 2, Juan Lin 2, Donna Yoo 1 and Claudene J. George 3* 1 Albert Einstein College of Medicine Bronx, New York, NY, United States, 2 Department of Epidemiology and Population Health, Albert Einstein College of Medicine Bronx, New York, NY, United States, 3 Montefiore Medical Center, Division of Geriatrics, Albert Einstein College of Medicine Bronx, New York, NY, United States Introduction: Diabetes mellitus is a common comorbidity among patients with coronavirus disease 2019 (COVID-19). Diabetic patients with COVID-19 have a two-fold increased risk of death and tend to have more severe infection compared to the general population. Metformin, a first-line medication for diabetes management, has anti-inflammatory and immunomodulatory effects. Previous studies focusing on metformin and COVID-19 clinical outcomes have had mixed results, with some showing a mortality benefit or decreased complications with metformin use. To date, few studies have analyzed such outcomes among a diverse, multiracial community. Methods: This was a retrospective review of patients with Type 2 diabetes and a confirmed COVID-19 infection admitted to an urban academic medical center from January 1, 2020 to May 7, 2020. Baseline characteristics were collected. The primary outcomes of the study were in-hospital mortality and length of stay (LOS). Results: A total of 4462 patients with Type 2 diabetes and confirmed COVID-19 were identified. 41.3% were Black, and 41.5% were Hispanic. There were 1021 patients in the metformin group and 3441 in the non-metformin group. Of note, more participants in the metformin group had comorbid disease and/or advanced diabetes. We found no statistically significant differences between the metformin and non-metformin group in in-hospital mortality (28.1% vs 25.3%, P=0.08) or length of hospital..