Insulin can promote the synthesis and storage of fat, reduce free fatty acids in blood, and inhibit the decomposition and oxidation of fat. When insulin is deficient, it can cause disorder of fat metabolism, reduce fat storage, enhance decomposition, and increase blood lipids, which can cause atherosclerosis and lead to serious cardiovascular diseases in the long run. At the same time, insulin deficiency can also lead to enhanced lipolysis in the body, generating a large number of ketone bodies and ketoacidosis. The main physiological role of insulin is to regulate the metabolic process, but also has the regulation of glucose metabolism, promote the uptake and utilization of glucose by tissue cells, promote glycogen synthesis, inhibit gluconeogenesis, so that blood sugar is reduced. It also has corresponding effects on protein, promoting the entry of amino acids into cells and promoting various aspects of protein synthesis to increase protein synthesis. The overall effect of insulin is to promote anabolism. Insulin is the only hormone in the body that lowers blood glucose and the only hormone that promotes glycogen, fat and protein synthesis at the same time.