Which hormone is released in response to low blood sugar levels?

Glucagon is the hormone released by the pancreas specifically in response to low blood sugar levels. When blood glucose levels decline, glucagon is secreted by the alpha cells of the islets of Langerhans in the pancreas. Its primary function is to raise blood glucose levels by promoting glycogenolysis, the breakdown of glycogen into glucose, in the liver. Additionally, glucagon stimulates gluconeogenesis, the production of glucose from non-carbohydrate sources. This rapid response helps to restore normal blood glucose levels, ensuring that the body's cells have a sufficient energy supply.

In contrast, insulin is released when blood sugar levels are high, serving to lower glucose levels by facilitating the uptake of glucose into cells and promoting its storage as glycogen. Cortisol, although it can influence glucose metabolism, is primarily related to stress responses and helps to increase blood glucose levels over a longer duration. Incretins are hormones that amplify insulin secretion in response to meals yet do not directly act in response to low blood sugar levels. Therefore, glucagon is specifically crucial for counteracting hypoglycemia by increasing blood sugar when it's low.