Normal values of blood glucose in the elderly are consistent with those of normal people of other age groups, with the normal range of fasting blood glucose corresponding to 3.9-6.1 mmol/L; random blood glucose should be <11.1 mmol/L; and 2-hour postprandial blood glucose value should be <7.8 mmol/L. The standard of glycemic control for elderly people with chronic diseases, diabetes mellitus, or seniority can be appropriately relaxed. Currently, the normal range of blood glucose values is based on epidemiological data, clinical studies, and the characteristic complications of diabetes (diabetic microangiopathy) to determine the diagnostic threshold for diabetes, which is not related to age segments. Diabetes mellitus can be diagnosed if there are typical symptoms of "three excesses and one deficiency" (excessive drinking, urination, and food intake, and weight loss) plus a venous plasma glucose measurement of ≥11.1 mmol/L or a fasting glucose of ≥7.0 mmol/L at any time of the day or a glucose measurement of ≥11.1 mmol/L at 2 hours after an OGTT. diagnosed as diabetes. If abnormal blood glucose is found, timely hospital consultation is recommended.