Insulin promotes the uptake and utilization of glucose by systemic tissues and inhibits the breakdown of glycogen and gluconeogenesis. Therefore, insulin has the effect of lowering blood sugar. When insulin is too much, blood sugar drops rapidly, brain tissue is most affected, and convulsions, coma, and even insulin shock can occur. Conversely, insufficient insulin secretion or insulin receptor deficiency often leads to elevated blood glucose; if it exceeds the renal sugar threshold, sugar is excreted from the urine, causing diabetes; and because of changes in blood composition (containing excess glucose), it also causes high blood pressure, Lesions such as coronary heart disease and retinal vascular disease. Insulin lowering blood sugar is the result of multiple effects:
(1) Promoting target cells in muscle, adipose tissue, etc. The cell membrane carrier transports glucose in the blood into cells.
(2) Enhancing phosphodiesterase activity, decreasing cAMP level, and increasing cGMP concentration by covalent modification, thereby increasing glycogen synthase activity, decreasing phosphorylase activity, accelerating glycogen synthesis, and inhibiting glycogen decomposition.
(3) Activate pyruvate dehydrogenase by activating pyruvate dehydrogenase phosphatase, accelerate the oxidation of pyruvate to acetyl-CoA, and accelerate the aerobic oxidation of sugar.
(4) Inhibition of gluconeogenesis by inhibiting the synthesis of PEP carboxykinase and reducing the gluconeogenesis.
(5) Inhibition of hormone-sensitive lipase in adipose tissue, slowing down fat mobilization, and making tissue use glucose increase.
Insulin regulates glucose metabolism
