What is the primary function of insulin in the body?

Insulin plays a crucial role in regulating blood glucose levels, primarily by promoting the uptake of glucose by cells throughout the body. When glucose is present in the bloodstream, such as after a meal, insulin is secreted by the pancreas. This hormone facilitates the transportation of glucose into muscle and fat cells, where it can be used for energy or stored as glycogen for later use. This process is essential for maintaining normal blood sugar levels and preventing hyperglycemia.

In addition to its primary role in glucose uptake, insulin also has effects on fat and protein metabolism, but the direct mechanism of lowering blood glucose through cellular uptake is the fundamental function that defines its importance in metabolic processes.

While stimulating appetite and regulating metabolism are various functions that can involve insulin, they are secondary to its primary role in glucose transport. Options that suggest insulin increases blood glucose levels are not aligned with its physiological function, as insulin's purpose is to lower blood sugar levels through enhanced cellular glucose uptake.