Diabetes with insulin generally does not have a significant impact on life expectancy if the condition is effectively controlled; if a diabetic’s blood glucose is poorly controlled, it may lead to a variety of complications, in which case life expectancy may be affected. As long as diabetic patients can control their blood glucose well for a long time, avoid acute complications and delay the occurrence and development of various chronic complications, they can often survive with the disease for a long time, which hardly affects their life expectancy. Patients with type 1 diabetes require insulin therapy at the onset of the disease and lifelong insulin replacement therapy; insulin therapy is preferred for newly diagnosed patients with type 2 diabetes who have significant symptoms of hyperglycemia, ketosis or diabetic ketoacidosis. In addition, patients with type 2 diabetes mellitus can start the combination therapy of oral hypoglycemic agents and insulin if their blood glucose still does not reach the control target on the basis of lifestyle and oral hypoglycemic agent therapy. Insulin therapy should be used as early as possible in the course of diabetes mellitus (including newly diagnosed type 2 diabetes) when significant weight loss occurs without an obvious cause. Insulin is an important method of glycemic control in diabetes, and diabetic patients need to follow the doctor’s instructions to actively treat and prolong the survival of diabetes as much as possible.