Objective To observe the changes of blood glucose in the elderly with multiple organ dysfunction syndrome (MODSE) induced by pulmonary infection, and to analyze the correlation between blood glucose with the incidence and severity of MODSE. Methods A retrospective study was carried out on 625 patients (≥65 years old) with pulmonary infection admitted in our hospital from January 2005 to December 2014. According to the onset of diabetes, they were divided into diabetes group and non-diabetes group. According to whether pulmonary infection induced MODSE or not, each group was further divided into MODSE subgroup and non-MODSE subgroup. The highest fasting blood glucose was compared between the MODSE subgroup and non-MODSE subgroup from the diabetes group or from the non-diabetes group. Spearman rank correlation analysis was used to analyze the correlation of blood glucose with the incidence and severity of MODSE. Results Among the 196 diabetes patients, MODSE occurred in 89 cases, and in 95 cases among the 429 non-diabetes patients. The highest fasting blood glucose level in the MODSE subgroup and non-MODSE subgroup from the diabetes group were (13.720±4.863), (7.439±3.043) mmol/L, and that from the non-diabetes group were (8.656±2.664), (5.679±1.332) mmol/L respectively, with the level significantly higher in the MODSE subgroup than in the non-MODSE subgroup (P<0.001). The highest fasting blood glucose in elderly pulmonary infection patients was positively correlated with the incidence and severity of MODSE (P<0.001). Conclusion The highest fasting blood glucose level is obviously increased in the elderly patients with MODSE due to pulmonary infection, and its changes are positively correlated with the incidence and severity of MODSE.