In: Anatomy and Physiology
Since polar molecules cannot be transported across the plasma membrane, carrier proteins called glucose transporters are needed for cellular uptake. Glucose transporters are found in the plasma membrane where they bind to glucose and enable its transport across the lipid bilayer. When all of the glucose transporters are involved in the transport and there is no transporter left to transport glucose into the cell, so the rate of glucose transport becomes constant and this is termed as Glucose Saturation.
Here's the graph, showcasing no increase in rate of glucose transport rate.
We can increase the rate of glucose transporter when we have reached saturation by giving:
INSULIN: Insulin acts by increasing the glucose transport rate of each transporter, increasing the number of functional glucose transporters, or by a combination of both mechanisms.