There are many reasons for insufficient insulin secretion, and the most common clinical reasons are autoimmune factors, insulin resistance and pancreatic injury. 1. Autoimmune factors: the pancreatic β-cells of type 1 diabetes mellitus patients are destroyed due to autoimmune factors, which can lead to insufficient insulin secretion. 2. Insulin resistance: It refers to the reduced sensitivity of the target organs of insulin action (mainly liver, muscle and adipose tissue) to insulin action, and insulin resistance will cause progressive insulin secretion insufficiency. 3. Pancreatic injury: In addition, when the pancreas is damaged by other factors, such as trauma, inflammation, tumor and so on, resulting in damage to the pancreatic β-cells, the amount of insulin secretion will also be reduced. It is recommended that patients with insufficient insulin secretion should go to the hospital in time to get a clear explanation of the cause under the guidance of the doctor, so as to carry out targeted treatment to avoid delaying the condition and triggering adverse consequences.