Pancreatic Hormones and Glucose Regulation

The pancreas keeps blood glucose within a usable range by coordinating two opposing hormones. Insulin, released from pancreatic beta cells, lowers glucose. Glucagon, released from alpha cells, raises it. After a carbohydrate-containing meal, rising glucose stimulates insulin release. Insulin helps skeletal muscle and adipose tissue take up glucose and signals the liver to stop releasing stored glucose. The liver then shifts from producing glucose to storing it as glycogen. This hepatic effect matters greatly: even when a person is not eating, the liver can raise blood glucose unless insulin restrains it. During fasting, insulin secretion falls and glucagon secretion rises. Glucagon tells the liver to break down glycogen and create new glucose through gluconeogenesis. This prevents hypoglycemia between meals and overnight. Insulin and glucagon are not simply an “off” and “on” switch. They are more like opposing instructions sent to the liver: insulin says, “Store fuel; stop sending glucose out,” while glucagon says, “Release fuel; the body needs circulating glucose.” Diabetes develops when insulin is absent, insufficient, ineffective, or mismatched to the body’s needs. Other pancreatic hormones fine-tune this system....