Which hormone decreases the level of glucose in the blood?

Insulin is the hormone responsible for decreasing the level of glucose in the blood. Its primary function is to facilitate the uptake of glucose by the cells, particularly muscle and fat cells. When blood sugar levels rise, such as after a meal, the pancreas secretes insulin. This insulin binds to insulin receptors on cell surfaces, allowing glucose to enter the cells, where it can be used for energy or stored as glycogen in the liver and muscles.

Additionally, insulin promotes the conversion of glucose into fatty acids in the liver and enhances the storage of fats, thereby reducing glucose levels in the bloodstream. This process is crucial for maintaining blood glucose homeostasis and preventing hyperglycemia, which can lead to serious health complications if left uncontrolled.

The other hormones mentioned, such as cortisol, adrenaline, and glucagon, generally serve to increase blood glucose levels through various mechanisms, like stimulating gluconeogenesis in the liver or promoting the breakdown of glycogen. Therefore, insulin is unique in its role as a critical regulator that decreases blood glucose levels.