Which hormone raises blood glucose levels and is antagonistic to insulin?

• A. Insulin
• B. Somatostatin
• C. Glucagon
• D. Epinephrine

Answer: (C)

Raising blood glucose in opposition to insulin is the job of glucagon. This hormone is produced by pancreatic alpha cells and acts mainly on the liver to increase glucose output. It stimulates glycogenolysis, breaking down stored glycogen into glucose, and promotes gluconeogenesis, making new glucose from non-carbohydrate substrates. The result is a rise in blood glucose, particularly during fasting or between meals, which counteracts insulin’s effects of lowering glucose by promoting uptake and storage in tissues. Somatostatin mainly inhibits hormone release and doesn’t directly raise glucose. Epinephrine does raise glucose as part of the stress response, but glucagon is the classic pancreatic hormone whose primary role is to oppose insulin by boosting hepatic glucose production, making it the best fit.