The development of diabetes may be related to genetic or environmental factors, autoimmunity, abnormal function of pancreatic islet cells and other reasons. 1. Heredity or environmental factors: Heredity plays an important role in diabetes mellitus, especially identical twins have a higher rate of homozygosity in heredity. In addition, ageing, over-nutrition, insufficient exercise and other combined effects cause obesity, especially central obesity, may also cause diabetes. 2. Autoimmunity: common in type 1 diabetes, it is due to the presence of antibodies against β-cells in the serum, as well as cellular immune disorders, etc. leading to the destruction of pancreatic islet β-cells, causing diabetes. 3. Islet cell dysfunction: insulin secretion is reduced or the body is insensitive to the action of insulin, or both, resulting in the inability to utilize and store glucose in the blood and diabetes. When diabetes occurs, it is recommended to go to a regular hospital, follow the doctor’s instructions for further examination, and carry out targeted treatment or therapy with the doctor’s help.