Which pancreatic hormone raises blood glucose levels and acts as an antagonist to insulin?

• A. Insulin
• B. Glucagon
• C. Somatostatin
• D. Pancreatic polypeptide

Answer: (B)

Glucagon is the pancreatic hormone that raises blood glucose and counteracts insulin. It’s produced by the alpha cells of the pancreatic islets and released when blood sugar is low. In the liver, glucagon binds its receptor and triggers a cAMP-based signaling cascade that activates glycogenolysis (breaking down glycogen) and promotes gluconeogenesis (making new glucose). The net effect is more glucose released into the bloodstream, which raises blood glucose levels during fasting or between meals. Insulin does the opposite—promotes glucose uptake and storage to lower blood sugar. Other options don’t primarily raise glucose or oppose insulin: somatostatin inhibits the release of multiple hormones, including insulin and glucagon; pancreatic polypeptide mainly influences pancreatic secretions and GI activity.