Diabetes mellitus is a group of metabolic diseases characterized by hyperglycemia. Hyperglycemia, in turn, is caused by defective insulin secretion or impairment of its biological action, or both. The long-term presence of hyperglycemia in diabetes leads to chronic damage and dysfunction of various tissues, especially the eyes, kidneys, heart, blood vessels and nerves. 1, genetic factors: diabetes has a family genetic susceptibility. But this heredity still needs the role of external factors, these factors mainly include obesity, physical activity reduction, diet structure is not reasonable, viral infection, etc. 2, obesity: obesity is an important cause of the onset of diabetes. Especially easy to trigger type 2 diabetes. Especially abdominal obese people. The mechanism mainly lies in the existence of obvious hyperinsulinemia in obese people themselves, and hyperinsulinemia can make insulin and its receptor affinity is reduced, resulting in insulin action is blocked, triggering insulin resistance. This requires more insulin secretion and release from pancreatic β- cells, which in turn triggers hyperinsulinemia. This is a vicious cycle of glucose metabolism disorder and beta-cell insufficiency, which eventually leads to serious defects in beta-cell function and type 2 diabetes. Insufficient activity: physical activity can increase tissue sensitivity to insulin, reduce body weight, improve metabolism, reduce insulin resistance, relieve hyperinsulinemia and reduce cardiovascular complications. Therefore, reduced physical activity has become an important factor in the development of type 2 diabetes. 4, diet structure: high fat diet can inhibit the metabolic rate to increase weight and obesity. Obesity triggers type 2 diabetes perennial meat eaters, diabetes incidence is significantly higher than perennial vegetarians. Mainly related to meat containing fat, protein calories are higher. Therefore, the diet should be diversified to maintain nutritional balance and avoid excess nutrition. 5, psychoneurological factors: in the process of the occurrence and development of diabetes, the important role played by psychoneurological factors is recognized by Chinese and foreign scholars in recent years. Because the mental tension, emotional excitement, psychological pressure will cause a large increase in the secretion of certain stress hormones, and these hormones are the hormones that raise blood sugar is also the hormone that fights with insulin. The long-term release of a large number of these hormones will inevitably cause disorders in the regulation of endocrine metabolism, causing hyperglycemia and leading to diabetes. 6, viral infection: some type I diabetes patients, is in the patient suffering from the flu, mumps and other viral infectious diseases after the onset of the disease.