The criteria for type 2 diabetic patients according to the blood glucose concentration in different periods are as follows: 1. The diagnosis standard for healthy people is fasting blood glucose not exceeding 6.1mmol/L and two hours after meal blood glucose not exceeding 7.8mmol/L; 2. Pre-diabetes is divided into two parts: impaired fasting blood glucose and impaired glucose tolerance, fasting blood glucose exceeding 6.1mmol/L and not exceeding 7mmol/L is impaired fasting blood glucose. Fasting blood glucose is normal and postprandial blood glucose is more than 7.8mmol/L and not more than 11.1mmol/L, which is called impaired glucose tolerance; 3. Diabetic patients with fasting blood glucose more than 7.0mmol/L or two hours after meal more than 11.1mmol/L.