According to the diabetes typing criteria proposed by the WHO Diabetes Expert Advisory Committee in 1999, there are four types of diabetes. The typing is mainly based on the pathogenesis of different diabetes and is divided into type 1 diabetes, type 2 diabetes, gestational diabetes and other special types. 1.What is type 1 diabetes? Type 1 diabetes occurs when the insulin-secreting pancreatic islet cells are destroyed, causing an absolute lack of insulin and a significant increase in blood glucose. Its incidence is very low, and the prevalence is about one-tenth of that of type 2 diabetes. In addition to genetic and viral infections, the pathogenesis is also related to autoimmunity. In type 1 diabetes, there are often autoantibodies that destroy islets in the body, including, for example, islet cell antibodies (ICA), insulin autoantibodies (IAA) and glutamic acid decarboxylase 65 (GAD65) antibodies, etc. This type occurs mostly in children and adolescents, with a thin body type and a rapid onset of disease, often accompanied by three symptoms and a tendency to ketosis. Acidosis tendency. Patients often need to inject insulin to maintain normal blood sugar. 2.What is type 2 diabetes? Type 2 diabetes is the most common type of diabetes, accounting for more than 90% of all diabetes, and most of our adults with diabetes belong to type 2 diabetes. These patients tend to be resistant to insulin action, at least in the beginning stages, but often for life. type 2 diabetes is mostly seen in adults and has a slow onset. Patients are not dependent on exogenous insulin for survival in the early stages of the disease or even throughout the course of the disease. Although their plasma insulin levels are normal or high, their blood glucose remains high due to the presence of insulin resistance. Most patients with type 2 diabetes are obese, and those who are not obese also tend to have increased abdominal fat. Type 2 diabetes has a clear genetic predisposition, so the immediate family members of patients with type 2 diabetes should also regularly monitor their blood glucose to avoid elevated blood glucose. type 2 diabetes patients often do not have enough high blood glucose to trigger the symptoms of diabetes that are valued by patients, and thus go undiagnosed for many years, but they are already at risk of developing major and minor vascular complications of diabetes. 3. What is gestational diabetes? Gestational diabetes is defined as the initial detection of reduced glucose tolerance or diabetes during pregnancy, excluding those with pre-existing diabetes and now combined with pregnancy. The pathogenesis of gestational diabetes is related to the increase of glucagon secretion during pregnancy, which increases insulin resistance and decreases insulin secretion, resulting in elevated blood glucose. Elevated glucose during pregnancy is inevitably associated with many diseases of the mother and fetus during pregnancy, such as gestational hypertensive syndrome in the mother and fetal growth restriction, miscarriage and preterm delivery. Therefore, it is currently recommended for pregnant women to be screened for diabetes at 24-28 weeks to avoid adverse effects of elevated glucose on the mother and fetus, and to re-evaluate the glucose metabolic status of mothers with gestational diabetes after delivery and for lifelong follow-up (details will be covered in a separate section). 4. Other special types of diabetes mellitus, which are rare in clinical practice, are diagnosed with more specialized knowledge and will not be discussed here.