Objective·To investigate the predictive value of the geriatric nutritional risk index (GNRI) for the occurrence of lung infection in hospitalized elderly patients with type 2 diabetes mellitus (T2DM).Methods·Elderly T2DM patients who were admitted to the Geriatric Department of Shanghai Tongren Hospital between June 2022 and June 2024 were retrospectively and consecutively enrolled. They were divided into infected and non-infected groups according to whether lung infection occurred during hospitalization. Baseline data (gender, age, height, weight, duration of diabetes, comorbidities, etc.) were collected and GNRI was calculated. A multivariate Logistic regression model was used to screen the independent risk factors for pulmonary infections,and the predictive value of GNRI for pulmonary infections in T2DM patients was analysed using receiver operating characteristic (ROC) curves.Results·A total of 264 elderly T2DM patients were enrolled, among whom 154 developed pulmonary infections. Significant differences were observed between the infected and non-infected groups in GNRI, albumin, leukocyte count, neutrophil ratio, lymphocyte ratio, glycated hemoglobin, fasting glucose, interleukin-6, C-reactive protein, and procalcitonin levels (P