A 20-year-old diabetic has a life expectancy of about 70-80 years as long as his blood sugar is well controlled. If the typing of diabetes is type 1 diabetes should be treated with insulin, the better the blood sugar control, the less chance of complications will occur. Many type 1 diabetic patients with poor blood sugar control will lead to diabetic nephropathy, renal insufficiency, and uremia. Many patients need dialysis treatment for a long time, and some patients often die of heart and lung failure due to infection, and their life expectancy may be around 40-50 years. If a patient with type 2 diabetes is controlled by diet and treated with glucose-lowering drugs or insulin, with better glycemic control and fewer complications, life expectancy of about 70-80 years is not a problem.