Which hormone raises blood sugar levels?

• A. Thyroxine
• B. Epinephrine
• C. Glucagon
• D. Estrogen

Answer: (C)

Regulation of blood glucose hinges on hormones that signal the liver to release or store glucose. Glucagon, released from pancreatic alpha cells when blood sugar drops, directly tells the liver to increase glucose output by promoting glycogen breakdown (glycogenolysis) and the production of new glucose (gluconeogenesis). This makes blood glucose rise back toward normal levels, which is why glucagon is the hormone that raises blood sugar.

Thyroxine mainly accelerates overall metabolism rather than directly controlling glucose release. Estrogen has only indirect and minimal direct effects on glucose regulation. Epinephrine does raise blood glucose in acute stress by activating liver glucose output as well, but glucagon is the primary hormonal signal for increasing hepatic glucose production in response to hypoglycemia.