Which hormone is primarily responsible for increasing blood glucose levels?

The hormone that primarily increases blood glucose levels is glucagon. It is produced by the alpha cells of the pancreas and plays a critical role in maintaining blood glucose homeostasis, especially during fasting or periods of low energy intake. When blood sugar levels drop, glucagon is secreted into the bloodstream and stimulates the liver to convert stored glycogen into glucose through a process known as glycogenolysis. This release of glucose from the liver into the bloodstream helps raise blood glucose levels back to a normal range.

While insulin is involved in lowering blood glucose levels by facilitating the uptake of glucose into cells, cortisol and epinephrine also play roles in glucose regulation, they do not act primarily to raise blood glucose levels in the same way that glucagon does. Cortisol promotes gluconeogenesis (the production of glucose from non-carbohydrate substrates) but primarily serves to modulate metabolic processes in response to stress. Epinephrine, or adrenaline, stimulates glycogen breakdown and elevates blood glucose levels, particularly during acute stress or physical activity, but again, glucagon is the primary hormone responsible for increasing glucose levels from stored glycogen when needed.