Diabetes mellitus (Diabetes) is divided into type 1 diabetes and type 2 diabetes. The percentage of type 2 diabetes is about 95% of the diabetic population. Type 1 diabetes Type 1 diabetes is an autoimmune disease. It is also called juvenile type, unstable type, and insulin-dependent type. Autoimmune diseases are caused by the body’s immune system attacking itself. Type 1 diabetes occurs in adolescents and young adults who lack insulin production and rely on exogenous insulin supplementation to stay alive. Type 1 diabetes is also common in children. Most children with type 1 diabetes have an abrupt onset, and within a few days, they may suddenly show marked excessive drinking and urination, drinking and urinating up to several liters per day, with increased appetite but weight loss. In young children, urine loss and wasting are common, drawing the attention of parents. The onset of the disease is often triggered by infection and improper diet. In infants and young children, the disease is often characterized by the symptoms of enuresis, and polyuria is easily ignored, and some do not come to the clinic until ketoacidosis occurs. Type 2 diabetes mellitus Type 2 diabetes mellitus is an adult-onset type of diabetes mellitus, also known as adult-onset, stable, non-insulin-dependent type. It mostly develops after the age of 35 to 40 and accounts for more than 90% of diabetic patients. The ability to produce insulin in the body of patients is not completely lost, some patients even produce too much insulin in their bodies, but the effect of insulin is greatly reduced, so the insulin in the body of patients is a relative deficiency. Type 2 diabetes has stronger hereditary and environmental factors, and is significantly heterogeneous. Clinical observations of insulin resistance are prevalent in type 2 diabetes, up to about 90%. Diabetes can be a major cause of death and disability by leading to infections, cardiac lesions, cerebrovascular lesions, renal failure, double vision, and lower extremity gangrene. Diabetic hyperosmolarity syndrome is a serious acute complication of diabetes mellitus, the initial stage of which can be characterized by polyuria, polydipsia, lethargy and unresponsiveness. As the body loses more water the disease progresses rapidly, with drowsiness, disorientation, seizure-like convulsions, hemiparesis and other stroke-like symptoms, and even coma. Gestational diabetes Gestational diabetes is a condition in which a woman develops diabetes during pregnancy. Clinical data show that about 2 to 3% of women develop diabetes during pregnancy and that the diabetes disappears spontaneously after the pregnancy. Gestational diabetes is more likely to occur in women who are obese and of advanced maternal age. Nearly 30% of women with gestational diabetes may later develop type 2 diabetes. Secondary diabetes is considered in the context of medical history when it is caused by pancreatitis, cancer, or major pancreatic resection. Patients with hyperpigmentation, hepatosplenomegaly, diabetes mellitus and iron metabolism disorders should be differentiated, but are less common. Other endocrinopathies have their own characteristics, and the differentiation can be analyzed in the context of the disease, generally without difficulty. Stress hyperglycemia or gestational diabetes mellitus should be differentiated by follow-up. It is usually recovered 2 weeks after the stress has disappeared, or can be identified during the follow-up after delivery.