Type 1 diabetes is correctly characterized as type 1 diabetes, in the early stages of the disease there may be some pancreatic islet function, as the disease gradually aggravates, pancreatic β-cells destruction increases, the function of the pancreatic islets gradually fail, and ultimately there may be no pancreatic islet function, and the need for lifelong insulin treatment. Type 1 diabetes mellitus is an autoimmune disease, with both genetic and environmental factors involved in its pathogenesis. In patients with genetic susceptibility, if they are not adversely affected by external factors such as viral infections, chemical toxins, diet, etc., pancreatic islet function is normal and blood glucose is within the normal range. When these external factors stimulate the body to undergo a series of autoimmune reactions mediated by T lymphocytes, the immune cells will keep attacking the pancreatic islet β-cells, and in the early stage of the disease through the compensatory effect of insulin, the blood glucose is in the normal range. With the aggravation of the disease, too much destruction of pancreatic β-cells, a decline in pancreatic function, when there is a loss of compensation, there will be a rise in blood glucose, and ultimately there may be no pancreatic function. Because of the absolute lack of insulin in the type 1 diabetic organism, patients need lifelong exogenous insulin replacement therapy and regular review of blood glucose. If type 1 diabetes is suspected, it is recommended to seek prompt medical attention and follow medical advice.