People with non-functioning pancreatic islets can survive for a long time. Insulin is the only hypoglycemic hormone secreted by pancreatic beta cells and is very important for maintaining normal blood glucose concentration in the body. When insulin secretion is reduced or its action is resistant for various reasons, abnormal glucose metabolism occurs, and diabetes can occur in severe cases. Without islet function there is almost no insulin secretion, and patients without islet function must rely on insulin therapy for a long time. The introduction of insulin is a boon for patients with type 1 diabetes, or those without islet function. Even if a patient’s own pancreas is not functional, he or she can choose an appropriate insulin treatment plan under the guidance of a doctor. By relying on exogenous insulin and maintaining a good blood sugar range for a long time, the development and progression of diabetes complications can be delayed and the patient can survive with the disease for a long time.