Which substance inhibits gluconeogenesis?

Insulin is known for its crucial role in regulating blood glucose levels, and one of its primary functions is to inhibit gluconeogenesis, the metabolic pathway that generates glucose from non-carbohydrate substrates. When insulin is released, particularly in response to increased blood glucose levels, it promotes glucose uptake by tissues, such as muscle and adipose tissue, and simultaneously suppresses the production of glucose by the liver through gluconeogenesis.

This process allows for better management of energy resources when glucose is readily available, promoting an anabolic state where the body can use carbohydrates rather than produce new glucose, which is especially important in preventing hyperglycemia. In contrast, substances like catecholamines and glucocorticoids tend to promote gluconeogenesis and raise blood glucose levels, while glycogen serves as a stored form of glucose rather than directly influencing gluconeogenesis. Therefore, insulin stands out as the key substance that actively inhibits this pathway, making it the correct answer.