This is a prospective randomized controlled study to evaluate consistency by finger stick blood glucose or venous blood glucose in different infiltration time (including the time between activation of the sensor and storage of the first blood glucose value) of Flash glucose monitoring(FGM). In this study, the relationship between the dynamic blood glucose and finger stick blood glucose or venous blood glucose in type 2 diabetes mellitus patients(T2DM), was explored. And the investigators also analyzed the deviation and accuracy of FGM in practical application,so as to provide a good reference for clinical application.

Inclusion Criteria:

• Patients with type 2 diabetes fit the 1999 who diagnostic criteria for diabetes
• Aged 18 or above
• Without serious complications, such as diabetic ketoacidosis, severe infection,severe cardiac insufficiency, severe liver and kidney diseases
• Voluntary and signed informed consent to participate
• Be able to read and understand Chinese, perform all research visits and tasks, and follow research instructions

Exclusion Criteria:

• Patients with known allergy to medical grade adhesive or isopropanol used for skin disinfection, edema, skin damage, scar, redness, infection, etc. during pregnancy or preparation of pregnancy or at the sensor application site (dorsal side of upper arm).
• The examinee took drugs such as ascorbic acid (vitamin C) and salicylic acid (an ingredient in aspirin and many painkillers) that affected the accuracy of the sensor.
• MRI is required during the study.
• The examinee had poor compliance and could not continue to complete the study.