J-shaped association between fasting blood glucose levels and COVID-19 severity in patients without diabetes

•FBG is J-shaped associated with COVID-19 severity in non-diabetic patients.•Optimal Fasting glycemic target for COVID-19 patients is 4.74–5.78 mmol/L.•Both low and high FBG levels are increase COVID-19 severe/critical rate. Coronavirus disease 2019 (COVID-19) has become a recognized worldwide pandemic. Researchers now know that mortality from COVID-19 can be reduced through early prevention measures. This retrospective, multi-centered study of 293 COVID-19 patients without diabetes explores the association between fasting blood glucose (FBG) levels and the risk of COVID-19 disease progression, with the goal of providing clinical evidence for glycemic targets in patients. The multivariate stepwise binary logistic regression analysis was used to test the dose–response effects of FBG levels on the risk of severe and critical condition in COVID-19 patients. FBG levels were plotted in quintiles with set at