The life expectancy of people with diabetes in their 20s varies greatly from person to person, and there is no specific value for the average life expectancy. If long-term blood glucose control is good, it may not affect life expectancy; if blood glucose control is poor and various complications occur, life expectancy will be shortened, and in serious cases, life can be jeopardized very quickly. Diabetes is a chronic disease that usually requires lifelong treatment. If the patient has good compliance, a positive attitude towards the disease, and long-term glycemic control is up to standard, life expectancy can be unaffected, and life expectancy is comparable to that of normal people. If diabetic patients are not actively treated, long-term poor glycemic control, blood glucose fluctuations, renal failure, diabetic foot, heart attack, cerebral infarction and other complications can occur, the expected survival period will be shortened, but the specific can live a few years, there is not a clinically accurate value. Diabetes ketoacidosis, hyperosmolar hyperglycemic coma can be life-threatening in severe cases. Diabetes in the 20s should actively control blood glucose, delay or avoid the occurrence and development of diabetic complications.