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

Glucagon is the hormone that is secreted in response to low blood sugar levels. Its primary role is to raise blood glucose levels by promoting the conversion of glycogen to glucose in the liver, which is released into the bloodstream. Glucagon is critical in maintaining glucose homeostasis, particularly during fasting or between meals when blood sugar levels can dip.

When blood sugar levels fall, the pancreas detects this change and releases glucagon from its alpha cells. This action not only stimulates the liver to release stored glucose but also encourages gluconeogenesis, the process of forming glucose from non-carbohydrate sources. Glucagon effectively counteracts the effects of insulin, which lowers blood sugar, ensuring that the body has a stable supply of glucose for energy.

In contrast, while hormones like cortisol and growth hormone can also influence blood sugar levels, they do not specifically respond to low blood sugar in the same direct manner as glucagon. Thyroid hormone, though important for metabolism, does not have a direct role in the immediate regulation of blood glucose levels in response to hypoglycemia. Thus, glucagon is uniquely positioned as the primary hormone responsible for elevating blood sugar levels in response to low glucose availability.