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 can lead to chronic damage and dysfunction of various tissues, especially the eyes, kidneys, heart, blood vessels, and nerves. The main causes include: 1. genetic factors: type 1 or type 2 diabetes have obvious genetic heterogeneity, diabetes has a family tendency to develop, 1/4-1/2 of patients have a family history of diabetes, clinically there are at least 60 kinds of genetic syndromes can be accompanied by diabetes. type 1 diabetes has multiple DNA loci involved in the pathogenesis, of which the DQ locus polymorphism in the HLA antigen gene is the most closely related. The closest relationship is found in type 2 diabetes with a variety of clear genetic mutations such as insulin gene, insulin receptor gene, glucokinase gene and mitochondrial gene, etc.; 2. Environmental factors: Nowadays, many people in our society eat too much and reduce physical strength and activity leading to obesity, which is one of the most important environmental factors in type 2 diabetes. Individuals with a genetic susceptibility to type 2 diabetes are prone to develop the disease. type 1 diabetes patients have abnormalities in the immune system, leading to an autoimmune response after infection with certain viruses such as coxsackievirus, rubella virus, mumps virus, etc., which destroy insulin B cells. There is no cure for diabetes, but it can be controlled by a variety of treatments, which include five main areas: education for diabetics, self-monitoring of blood glucose, diet for diabetes, exercise therapy, and medication.