After excluding acute infections, trauma, and other factors that affect blood glucose, the presence of blood glucose 18mmol/L in the elderly is generally more serious. The normal range of fasting blood glucose is 3.9~6.1mmol/L, and the normal range of blood glucose two hours after meal should be less than 7.8mmol/L; fasting blood glucose is greater than or equal to 7mmo/L, and blood glucose two hours after meal is greater than or equal to 11.1mmol/L, and there are typical diabetes mellitus “three more and one less” symptom, then we can Consider diabetes. For older patients with diabetes, a blood glucose of 18 mmol/L exceeds the glycemic control goal. Long-term poor glycemic control may lead to a series of complications such as diabetic nephropathy, diabetic macrovascular lesions, diabetic foot, etc. It is also necessary to suspect whether acute complications such as diabetic ketoacidosis have occurred. Elderly people with a blood glucose of 18 mmol/L are advised to go to the hospital and ask the doctor to make a judgment.