Which hormone is released by the pancreas to regulate blood glucose levels?

The hormone released by the pancreas to regulate blood glucose levels is insulin. Insulin plays a crucial role in maintaining homeostasis by lowering blood glucose levels when they become elevated, such as after eating. It facilitates the uptake of glucose by body tissues, primarily muscle and fat cells, allowing these cells to utilize glucose for energy. Insulin also promotes the storage of glucose in the liver in the form of glycogen, further helping to control blood glucose levels.

The other options pertain to different roles in the body. Glucagon, while also produced by the pancreas, works oppositely to insulin by raising blood glucose levels when they are too low. Cortisol is a hormone produced by the adrenal glands, which affects metabolism and stress response but is not directly responsible for blood glucose regulation. Adrenaline, also known as epinephrine, influences the "fight or flight" response and increases blood glucose levels during stress but is not the primary hormone for regulating glucose levels in a steady state. Thus, insulin is the key hormone involved in lowering blood glucose levels in the body.