Inclusion Criteria:  Trial group  Study time: June 1, 2021, to January 1, 2022; Study site: The First Affiliated Hospital of Shandong First Medical University; 25-65 years old (including upper and lower limits), male or female; Meeting the diagnostic criteria of type 2 diabetes (according to 1997 WHO's diagnostic criteria for type 2 diabetes); Fasting blood glucose < 10 mmol/L; HbA1c ≤ 11.0%.  Control group  Study time: June 1, 2021, to January 1, 2022; Study site: The First Affiliated Hospital of Shandong First Medical University; Relatively healthy people without type 2 diabetes mellitus diagnosis; Participants whose sex and age and BMI matched with the experimental group.  Exclusion Criteria:  Trial group and Control group  Participants with diabetic retinopathy; Participants with diabetic neuropathy; Participants with diabetic nephropathy; Participants have unilateral or bilateral carotid plaque; Participants have a history of cardio-cerebrovascular disease; Participants have a history of respiratory disease; Participants complicated with hypertension; Participants complicated with hyperlipidemia; Participants have a smoking history (including previous smoking history); Participants complicated with malignant tumor. Participants are currently taking anticoagulants or vasodilators; Participants do not sign a written informed consent form.