Backgrounds: Stress hyperglycemia ratio (SHR) reflects the acute blood glucose change in response to acute illnesses or injuries, including pneumonia.We aimed to investigate the associations of SHR with systemic inflammation and clinical outcomes in diabetic inpatients with pneumonia on admission.Methods: A multicenter and retrospective study was conducted among diabetic inpatients with pneumonia on admission via electronic medical records from 2013 to 2019 in Ruijin Hospital, Shengjing Hospital, and China-Japan Friendship Hospital. Results: The study included 1631 diabetic inpatients with pneumonia on admission. Patients of the fourth quartile (Q4) of SHR on admission showed significantly elevated systemic inflammation compared with those of the first quartile (Q1), second quartile (Q2), or third quartile (Q3) of SHR, including more white blood cells (9.