What substance does the pancreas secrete to lower blood glucose levels?

The pancreas secretes insulin to lower blood glucose levels. Insulin is a hormone produced by the beta cells of the pancreatic islets of Langerhans in response to elevated blood sugar levels, such as after a meal. Its primary function is to facilitate the uptake of glucose by cells, particularly in muscle and adipose tissues, as well as to promote the storage of glucose in the form of glycogen in the liver. By enabling cells to use glucose for energy, insulin effectively lowers the concentration of glucose in the bloodstream and helps maintain metabolic homeostasis.

In contrast to insulin, glucagon is secreted by the alpha cells of the pancreas and works to raise blood glucose levels by promoting glycogenolysis and gluconeogenesis in the liver. Cortisol, a hormone released from the adrenal glands, plays a role in increasing blood glucose levels during stress by mobilizing stored energy. Adrenaline (or epinephrine) also raises blood sugar in response to stress and helps prepare the body for a 'fight or flight' response. However, neither glucagon, cortisol, nor adrenaline functions to lower blood glucose levels as insulin does.