According to the current understanding of the etiology of diabetes, diabetes is classified into four types: Type 1 diabetes: absolute insulin deficiency due to destruction of pancreatic beta cells. Type 2 diabetes: insulin resistance with insufficient insulin secretion. Other specific types of diabetes mellitus: hereditary diabetes mellitus due to abnormalities in genes related to glucose metabolism or secondary diabetes mellitus due to other diseases. Gestational diabetes mellitus: abnormal glucose metabolism found during pregnancy, excluding those with existing diabetes mellitus combined with pregnancy.