Which statement best describes how insulin regulates blood glucose in a healthy person?

• A. It increases glucose production by liver
• B. It blocks glucose transport into cells
• C. It stimulates the uptake of glucose by cells of the body
• D. It inhibits glycolysis

Answer: (C)

Insulin’s main job after a meal is to lower blood glucose by telling cells to take in more glucose from the bloodstream. It does this by signaling muscle and fat cells to move GLUT4 glucose transporters to their surfaces, which increases glucose entry into those cells. This rapid uptake directly reduces circulating glucose levels.

Insulin also signals the liver to reduce glucose production and to store glucose as glycogen, contributing to lower blood sugar, but the most immediate and widespread effect is the stimulation of glucose uptake by body cells, making this the best description.

Why the other ideas aren’t correct in this context: increasing glucose production by the liver would raise blood glucose; blocking glucose transport into cells would prevent uptake and raise blood glucose; inhibiting glycolysis would limit glucose use inside cells rather than promote its clearance from the blood.