A series of metabolic disorders, such as sugar, protein, fat, water and electrolyte, are caused by the absolute or relative deficiency of insulin secretion and the decrease of sensitivity of target tissues and cells to insulin. Clinically, hyperglycemia is the main sign, and long-term illness can cause multiple system damage. When the illness is severely punished or stressed, acute metabolic disorders, such as ketoacidosis, will occur. Diabetes mellitus is mainly divided into four types: 1 type accounts for 5%, mainly occurring in adolescents; Type 2 accounts for more than 90%, which is more common in middle-aged and elderly people over 40 years old; Special types include definite etiology and secondary diabetes; Gestational diabetes mellitus (GDM) occurs in the second and third trimesters of pregnancy. First, the main clinical type of diabetes Insulin-dependent diabetes mellitus (IDDM, type I) can occur at any age, but most of them occur in adolescence. The clinical features are acute onset, obvious symptoms such as polyphagia, polyuria, polydipsia and weight loss, and a tendency to ketoacidosis, which requires insulin treatment to maintain life. The positive rate of autoantibodies of islet cells in blood at the early stage of onset is high. Oral glucose islet release test showed that the basal insulin level was lower than normal, and the insulin secretion curve was low after glucose stimulation, suggesting insulin deficiency. Second, non-insulin-dependent diabetes mellitus (NIDDM, type II) can also occur at any age, but it is more common in middle-aged and elderly people after 40 years old. Most patients have a slow onset and relatively mild or asymptomatic clinical symptoms. There is no tendency of ketoacidosis, but ketoacidosis or hyperosmotic coma can also occur under certain incentives. Dependent on insulin, but when diet and oral hypoglycemic drugs are not effective, or because of complications and accompanying diseases, insulin is sometimes needed to control hyperglycemia. Autoantibodies of islet cells were positive. Fasting plasma insulin level can be normal, slightly lower or higher than normal. The response of insulin to glucose stimulation can be slightly lower, basically normal or higher than normal, and the secretion peak is delayed. Third, the occurrence of type II diabetes is controlled by genes. There are many factors that affect blood sugar, and each link may be determined by one or several specific genes. Any genetic abnormality can lead to diabetes, so most scholars believe that diabetes is not inherited by a single gene, but a genetic disease caused by multiple gene variations. The inheritance of abnormal genes makes the offspring susceptible to diabetes and develops into diabetes under the circumstances of external factors. Type ⅱ diabetes can be divided into obese type and non-obese type. The pathogenesis of obese type II diabetes mellitus is long-term overeating. Because of the insulin receptor and post-receptor defects on insulin target cells, it stimulates islet B cells or prevents sugar and nutrients from entering cells and being fully utilized, resulting in hyperglycemia. Hyperglycemia stimulates islet B cells to increase insulin secretion, which leads to hyperinsulinemia, and then leads to the decrease of insulin receptors in target cells, that is, the number of insulin receptors decreases, and the sensitivity of target cells to insulin decreases, resulting in insulin resistance. Secondly, obese people have less physical activity and low carbohydrate utilization rate, which also increases the burden of islet B cells. The above situation has a long-term strong stimulation to islet B cells, and over time, islet B cells in people susceptible to hereditary diabetes lose their compensatory ability and produce diabetes. Non-obese type 2 diabetes may have post-receptor dysfunction of target cells at the beginning, that is, insulin resistance. People who are prone to hereditary diabetes have defects in islet B cells and cannot adapt to insulin resistance, so diabetes occurs. Non-obese subtype of type 2 diabetes mellitus produces insulin with abnormal structure due to gene mutation, which does not have the biological activity of normal insulin, thus causing diabetes; Autosomal dominant inheritance of non-obese type 2 diabetes mellitus: abnormal amino acid at the 25th position of insulin B chain can also cause diabetes mellitus. Therefore, this classification is not based on the severity of the disease, but has its own reasons. Pre-type 2 can be relieved by diet and exercise ~ Don't worry too much, I wish you health ~