If a diabetic patient takes regular insulin therapy and has better glycemic control, it usually has little effect on life expectancy and can reach the average life expectancy of the general population. If the blood sugar control is not satisfactory, it will significantly affect the life expectancy of patients. If a diabetic patient takes glucose-lowering drugs or subcutaneous insulin for glucose-lowering treatment under the guidance of a doctor, and the blood glucose is controlled steadily to meet the standard and the damage to target organs is minimal, the patient’s life expectancy is comparable to that of a normal population. If the blood glucose control is not satisfactory, a variety of target organ damage will appear prematurely, such as diabetic nephropathy, which can lead to renal insufficiency and even uremia; diabetic macroangiopathy, which can cause a variety of cardiovascular and cerebrovascular diseases, all of which can greatly shorten the life expectancy of patients. There are individual differences in the impact of diabetes on patients’ life expectancy, and there is no clear clinical time point for how long they can live. Patients with diabetes are advised to take standardized treatment as early as possible and strictly control their diet to avoid serious target organ damage.