Objective To explore the changes of fasting blood glucose in elderly non-diabetic patients with pulmonary infection, and investigate its value in the diagnosis of multiple organ dysfunction syndrome in the elderly (MODSE). Methods A retrospective study was carried out on 429 non-diabetic patients (over 65 years old) with pulmonary infection in our hospital from January 2005 to December 2014. According to whether pulmonary infection induced the onset of MODSE, the patients were divided into MODSE group (n=95) and non-MODSE group (n=334). The highest level of fasting blood glucose was compared between the two groups. SPSS 17.0 software was used to analyze the data. The quantitative data were expressed as mean±standard deviation ([AKx-D]±s), and the results were compared with Student’s t test. Enumeration data were expressed as percentage, and inter-group comparison was carried out with Chi-square test. The receiver operating characteristic (ROC) curve was used to determine the cut-off value of blood glucose levels for the MODSE diagnosis. Results The highest fasting blood glucose level in the MODSE group was significantly higher than that in the non-MODSE group [(8.656±2.664) vs (5.679±1.332)mmol/L, t=10.523, P<0.001]. When the cut-off value of fasting blood glucose was 6.875 mmol/L, the sensitivity was 83.2%, the specificity was 90.1%, the area under the ROC curve was 0.880, and 95%CI was 0.835-0.926 (P<0.001), with high diagnostic value. Conclusion The changes of fasting blood glucose are of value in the diagnosis of MODSE induced by pulmonary infection for the elderly non-diabetic patients. Fasting blood glucose ≥6.875 mmol/L can be used as an index in diagnosis of MODSE induced by pulmonary infection.