In general, two or more results of fasting blood glucose > 7.0 mmol/L and 2-hour postprandial blood glucose > 11.1 mmol/L are sufficient for a preliminary diagnosis of diabetes mellitus. Diagnosis of diabetes mellitus should be combined with blood glucose level and other related tests and symptoms, fasting blood glucose >7mmol/L, or 2-hour postprandial blood glucose >11.1mmol/L, glucose tolerance and pancreatic islet-releasing function and other tests, as well as observing the presence of polydipsia, polyphagia, polydipsia, and weight loss, which are the three polydipsia and one hypophagia symptoms. If fasting blood glucose >7mmol/L, 2 hours after meal blood glucose >11.1mmol/L, and at the same time have three more and one less symptoms, can be diagnosed as diabetes mellitus. If there are no three more or one less symptoms, if there is fasting blood glucose > 7mmol / L, 2 hours after meal blood glucose > 11.1mmol / L, need to choose a day to review the fasting blood glucose or 2 hours after meal blood glucose, or review the glucose tolerance, etc., to confirm the diagnosis of diabetes mellitus. In addition, diabetic patients may not take hypoglycemic drugs for 3-6 months after the diagnosis, but first carry out dietary control, pay attention to low-sugar and low-fat diet, and strengthen physical exercise.