There is no uniform data on the average life expectancy at 40 years old with diabetes, the average life expectancy is related to the control of diabetes, if the blood sugar control is good and there are no other complications, the average life expectancy is no different from normal people. With the improvement of living conditions, the incidence of diabetes in China is also getting higher and higher, diabetes is a chronic disease characterized by high glucose metabolism, if the long-term poor control of blood sugar will produce a series of complications. In fact, it is not the diabetes itself that leads to a shorter life expectancy, but a series of complications caused by it, such as coronary heart disease, cerebrovascular disease, renal disease, eye disease and so on, which have a great impact on the physical and mental health of the patients. Diabetes is not curable, but blood sugar can be controlled, so in general patients need to control blood sugar well, reduce the occurrence of complications, can also live a long life. If the body appears uncomfortable symptoms, it is recommended that the regular hospital consultation, so as not to delay the condition.