Objective To investigate the clinical characteristics and pathogen distribution of community-acquired pneumonia (CAP) combined with type 2 diabetes mellitus (T2DM), based on bronchoalveolar lavage fluid (BALF) metagenomic next-generation sequencing (mNGS) test. Methods In this cross-sectional study, CAP patients with BALF mNGS test were screened from April 2023 to April 2024. The patients were divided into a single CAP group (CAP group) and a CAP combine with T2DM group (CAP+T2DM group). The data of demographics, underlying diseases, complications, and laboratory tests including blood routine, inflammatory parameters, liver and renal functions, random blood glucose (RGB), hemoglobin A1C (HbA1c), and BALF mNGS tests were collected and compared between the two groups. Results Ultimately, 86 patients were included, with 45 in the CAP group and 41 in the CAP+T2DM group. Compared with the CAP group, the CAP+T2DM group had higher platelet count [(272.44±128.57)×109/L vs. (215.00±100.06)×109/L], erythrocyte sedimentation rate [(75.63±35.19) vs. (59.69±34.47) mm/h], RGB [10.8 (9.1, 13.5) vs. 6.5 (5.8, 7.8) mmol/L], HbA1c [8.2% (7.3%, 8.5%) vs. 5.7% (5.5%, 6.1%)], and fungi infection rate (65.9% vs. 40.0%), and the differences were statistically significant between the two groups (P<0.05). Conclusion CAP patients with T2DM have increased levels of platelet and erythrocyte sedimentation rate, and are at higher risk for fungi infection, which potentially leads to worse outcome.