The main criteria for determining diabetes mellitus include blood glucose testing (fasting blood glucose, 2-hour postprandial blood glucose, random blood glucose) and glycosylated hemoglobin. 1. Blood glucose test: including fasting blood glucose test, postprandial blood glucose test and random blood glucose test, and combined with the symptoms of diabetes mellitus three more and one less. If diabetes symptoms + fasting blood glucose ≥7mmol/l or 2h after sugar load ≥11.1mmol/l or random blood glucose ≥11.1mmol/l, diabetes can generally be diagnosed. If there are no symptoms of diabetes mellitus, review on another day is required for confirmation. 2. Glycated hemoglobin: In general, the reference range of glycated hemoglobin in healthy people is about 4%-6%. Glycated hemoglobin is used internationally as a diagnostic indicator for diabetes mellitus, with ≥6.5% as the cut-off point. This indicator is influenced by certain factors such as medications, blood pigmentation and even age. Once diagnosed with diabetes, you need to control your diet, exercise appropriately, take glucose-lowering medication under the guidance of your doctor if necessary, and go to the hospital for regular checkups.