Which hormone raises blood glucose?

• A. Melatonin
• B. Growth Hormone
• C. Glucagon
• D. Insulin

Answer: (C)

Raising blood glucose is achieved by hormones that signal the liver to produce and release glucose. Glucagon, released from pancreatic alpha cells when blood sugar falls, acts on liver cells to boost glucose output. It does this by activating pathways that promote glycogen breakdown (glycogenolysis) and the production of new glucose from non-carbohydrate sources (gluconeogenesis). The net result is an increase in plasma glucose, helping to restore normal levels.

Growth hormone can also raise blood glucose, but its effect is more gradual and indirect, mainly by antagonizing insulin and promoting glucose production and lipolysis over time. Melatonin isn’t involved in acute glucose regulation, and insulin lowers blood glucose by promoting uptake and storage. Therefore, glucagon is the hormone that directly raises blood glucose.