How long you can live with diabetes at the age of 20 varies from person to person and needs to be determined by the type of diabetes. The life expectancy of diabetic patients is not only related to their age at the time of diagnosis and the presence of complications, but more importantly, the patient’s awareness of the disease and the degree of attention paid to it. If the patient has good compliance, treats the disease more positively, and makes long-term blood sugar control reach the standard, the life expectancy is almost equal to that of normal people, and the quality of life is better, so that the patient can study and live normally, get married and have children. If patients take a laissez-faire attitude towards the disease and do not actively improve their lifestyles and treatment, it will cause drastic fluctuations in blood sugar and thus various complications of diabetes. As the disease progresses gradually, when renal insufficiency, heart attack, heart failure, cerebral infarction, retinopathy or diabetic foot appear, the patient’s quality of life will be seriously affected and the expected survival period will be shortened, but there is no exact clinical value for how many years they can live. Therefore, diabetic patients should actively engage in lifestyle intervention and treatment, such as prohibiting smoking and alcohol consumption, as well as a diabetic diet and appropriate daily aerobic exercise, and use medication reasonably under the guidance of a physician to control blood sugar, reduce complications and prolong survival.