Which hormone lowers blood glucose levels?

• A. Adrenaline
• B. Insulin
• C. Glucagon
• D. Thyroid hormone

Answer: (B)

When blood glucose rises, the body releases insulin to bring it down. Insulin, produced by pancreatic beta cells, tells cells to take in glucose from the bloodstream. It does this mainly by increasing the number of GLUT4 glucose transporters on muscle and fat cells, so more glucose moves into those cells. In the liver, insulin promotes turning glucose into glycogen (glycogenesis) and also supports glucose breakdown for energy (glycolysis), while it suppresses processes that generate new glucose. The net effect is a lower level of glucose circulating in the blood.

Other choices don’t have this glucose-lowering effect in the same way: adrenaline (epinephrine) and glucagon raise blood glucose by signaling the liver to break down glycogen and produce more glucose, especially during stress or fasting. Thyroid hormone influences overall metabolic rate but does not directly lower blood glucose in the immediate sense.