What hormone is secreted by the pancreas to lower blood sugar levels?

The hormone secreted by the pancreas to lower blood sugar levels is insulin. Insulin plays a crucial role in glucose metabolism by facilitating the uptake of glucose into the body's cells, particularly in muscle and fat tissues. When blood sugar levels rise—such as after eating—a signal is sent to the pancreas to release insulin. This hormone acts on target cells, promoting the absorption of glucose, thereby lowering blood glucose concentrations in the bloodstream.

In addition to its effects on glucose, insulin also helps to inhibit gluconeogenesis in the liver, which is the process of producing glucose from non-carbohydrate sources, further contributing to the reduction of blood sugar levels. Due to these functions, insulin is essential for maintaining homeostasis of glucose levels in the body, preventing conditions such as hyperglycemia, which could lead to diabetes if not properly regulated.

Other hormones listed, such as glucagon and epinephrine, typically work to increase blood sugar levels by promoting gluconeogenesis and glycogenolysis, while cortisol has a more complex role in metabolism and stress response, generally functioning to increase blood sugar levels as well.