Postprandial blood glucose of 19mmol/L is not normal, consider diabetes, patients need to pay attention. The normal value of fasting blood glucose is 3.9-6.1mmol/L, 2-hour postprandial blood glucose is less than 7.8mmol/L, and random blood glucose is less than 11.1mmol/L. Diagnostic criteria for diabetes mellitus: diabetes mellitus can be diagnosed by fasting blood glucose ≥7.0 mmol/L, or 2-hour post glycemic load blood glucose ≥11.1 mmol/L, or random blood glucose ≥11.1 mmol/L, accompanied by three more and one less symptom (drinking, eating and urinating more, and weight loss). Diabetes mellitus is also considered in the absence of diabetic symptoms with fasting blood glucose ≥7.0 mmol/L or random blood glucose ≥11.1 mmol/L monitored twice on non-same day. Postprandial blood glucose of 19 mmol/L is considered as a possibility of diabetes mellitus.