Which of the following best describes the primary function of insulin in glucose metabolism?

• A. It inhibits glycolysis in muscle and adipose tissue.
• B. It promotes the uptake of glucose into cells, lowering blood glucose levels.
• C. It increases gluconeogenesis in the liver.
• D. It stimulates the breakdown of glycogen to release glucose into the bloodstream.

Answer: (B)

Verified step by step guidance

1. Understand the role of insulin in glucose metabolism: Insulin is a peptide hormone secreted by the pancreas in response to high blood glucose levels. Its primary function is to regulate blood glucose levels by promoting glucose uptake into cells and facilitating its storage or utilization.
2. Analyze the options provided: Evaluate each statement to determine whether it aligns with the known functions of insulin. For example, insulin does not inhibit glycolysis; instead, it promotes glucose utilization in tissues like muscle and adipose tissue.
3. Focus on the correct mechanism: Insulin promotes the uptake of glucose into cells by increasing the expression of glucose transporters (e.g., GLUT4) on the cell membrane, particularly in muscle and adipose tissue. This action lowers blood glucose levels.
4. Eliminate incorrect options: Insulin does not increase gluconeogenesis (glucose production in the liver); instead, it inhibits gluconeogenesis. Similarly, insulin does not stimulate glycogen breakdown; it promotes glycogen synthesis in the liver and muscle.
5. Conclude with the correct answer: The best description of insulin's primary function in glucose metabolism is that it promotes the uptake of glucose into cells, thereby lowering blood glucose levels.