Patients with high blood glucose may have diabetes mellitus, which requires tests for the severity or control of abnormal glucose metabolism, pancreatic β-cell function, complications, and tests related to etiology and pathogenesis. 1. Examination of the severity or control of abnormal glucose metabolism: urine glucose measurement, blood glucose measurement and oral glucose tolerance test, glycated hemoglobin and glycated plasma albumin measurement can be performed. 2. Pancreatic β-cell function test: insulin release test, C-peptide release test, and other methods of detecting β-cell function, such as intravenous glucose-insulin release test, high glucose clamp test, and so on. 3. Complications examination: patients may have acute or chronic complications, for acute complications, ketone body, electrolytes, blood gas analysis, etc. For chronic complications, vascular ultrasound, funduscopic examination, limb electromyography, etc. can be carried out. 4. Examination about the etiology and pathogenesis: insulin sensitivity examination, genetic analysis and so on can be carried out. Patients with high blood glucose should go to the hospital in time, and the specific tests that need to be done need to be judged by the doctor according to the patient’s specific situation.