Which of the following statements may be associated with the activity of insulin?

• A. Increases blood glucose levels
• B. Decreases glucose uptake by muscle and fat cells
• C. Stimulates release of hepatic glucose into the blood
• D. Stimulates glycogenesis in the liver

Answer: (D)

Insulin’s main role after eating is to store the glucose that’s in the bloodstream. In the liver, it activates glycogen synthase, the enzyme that builds glycogen, and inhibits glycogen phosphorylase, which would break down glycogen. This push toward glycogen synthesis converts glucose into stored form and lowers the liver’s glucose output, helping to bring blood glucose back down. The other ideas describe opposite effects: insulin does not raise blood glucose, it actually lowers it; it promotes glucose uptake into muscle and fat, not decreases it; and it suppresses the liver’s release of glucose rather than stimulate it. So the statement that it stimulates glycogenesis in the liver best reflects insulin’s action.