Final answer:
Insulin is a hormone that regulates blood glucose levels by promoting the uptake of glucose into cells and its storage as glycogen in the liver and muscle cells.
Step-by-step explanation:
The hormone insulin is crucial for regulating blood glucose levels. It is secreted by the pancreas when blood glucose levels rise, such as after consuming a meal. The role of insulin is to promote the uptake of glucose into cells, particularly into the liver and muscle cells. Once inside these cells, the glucose is often converted into a substance called glucose-6-phosphate. This conversion establishes a concentration gradient that favors the movement of glucose from the blood into cells. In addition, insulin stimulates the liver and muscle cells to store glucose in the form of glycogen. Therefore, insulin does not immediately change glucose into fructose, amino acids, or lipids; instead, insulin aids in the transformation of glucose into glycogen for storage.