Metabolomics is an emerging "omics" after genomics, transcriptomics and proteomics, which can reflect the physiological state of organisms more directly and accurately. Whether metabolite differences exist in patients with type 2 diabetes of different stages and whether such metabolite differences can be used as potential markers have not yet been studied, which is of great significance to explore. In this study, 105 patients with different stages of type 2 diabetes mellitus were enrolled according to the inclusion and exclusion criteria, and the metabolites in the samples were detected by ultra-high performance liquid chromatography coupled with tandem time-of-flight mass spectrometry (UHPLC-Q-TOF MS) after the blood samples were collected, and the corresponding investigative data were collected, and then baseline and demographic analyses, metabolomics data processing, and analysis of the results were carried out to provide a reference for the identification of metabolic markers and to provide a reference for the identification of significant metabolic markers in diabetic patients.

Inclusion Criteria:

1. Age 18 to 75 years old
2. Population of patients with type 2 diabetes mellitus of different stages
3. Subjects or legal representatives gave informed consent to voluntarily join the study by signing an informed consent form.

Exclusion Criteria:

1. patients with severe acute underlying brain, cardiac, pulmonary, hepatic, renal and other conditions that the investigator believes to be influential
2. Patients diagnosed with any malignancy within the previous 5 years;
3. Received any form of oncological treatment including surgery, radiotherapy/chemotherapy, endocrine therapy, targeted therapy and immunotherapy prior to entry for blood sampling;
4. Organ transplant recipients or previous non-autologous (allogeneic) bone marrow or stem cell transplant recipients;
5. Those who have received blood transfusion therapy 1 month prior to the blood draw;
6. Patients with blood-borne diseases such as hepatitis, syphilis, and HIV;
7. Patients with other factors that, in the opinion of the investigator, influence the study.

Blood samples were collected from type 2 diabetic patients with different stages of diabetes mellitus (pre-stage, early-stage, and mid-late-stage), 35 cases in each stage, 105 cases in total