What is secreted when blood glucose levels are elevated?

When blood glucose levels are elevated, the pancreas secretes insulin. Insulin is a hormone that plays a critical role in glucose metabolism. Its primary function is to facilitate the uptake of glucose by cells, particularly muscle and fat cells, which helps lower blood glucose levels to a normal range.

Insulin also encourages the liver to convert glucose into glycogen for storage, thereby reducing the amount of glucose circulating in the bloodstream. This response is crucial for maintaining homeostasis, as chronic high blood sugar levels can lead to serious health issues, including diabetes.

In contrast, while glucose is the substance that is elevated and the focus of this question, it is not secreted by the body. Instead, insulin is actively released in response to high glucose levels. Adrenalin (or epinephrine) and glucagon serve different functions; adrenalin is involved in the body's fight-or-flight response and can increase blood sugar levels, while glucagon is secreted when blood sugar levels are low, stimulating the liver to release stored glucose. Thus, insulin is the hormone specifically secreted in response to elevated blood glucose levels.