The common types of diabetes are type 1 and type 2 diabetes, and gestational diabetes. The development of type 1 diabetes is associated with genetic, autoimmune, and environmental factors. The onset of type 2 diabetes is associated with genetic, environmental, insulin resistance, and beta cell function defects. Gestational diabetes mellitus is related to factors such as relative deficiency of insulin secretion and insulin resistance. 1. Type 1 diabetes mellitus: genetic factors play an important role in type 1 diabetes mellitus; moreover, viral infections such as mumps virus and coxsackie virus are also related to the onset of type 1 diabetes mellitus; the body’s immune system attacks the pancreatic β-cells can also cause insulin secretion or reduced secretion; all of the above factors may cause the onset of type 1 diabetes mellitus. 2. Type 2 diabetes mellitus: genetic susceptibility can be caused by the total effect of single gene or multiple gene abnormalities; environmental factors such as aging, over-nutrition, and insufficient physical activity; insulin resistance and β-cell dysfunction; abnormally elevated blood glucose-raising hormones; all of the above may lead to the development of type 2 diabetes mellitus. 3. Gestational diabetes mellitus: its etiology is mainly related to the increase of insulin resistance and relative insufficiency of insulin secretion after pregnancy. In daily life, you should avoid the factors that cause the onset of diabetes, the presence of the above factors are recommended to go to the hospital if necessary.