And what insulin basically does is it decreases the concentration of glucose inside the blood plasma back to a normal value of about 100 milligrams per deciliter. So that is the normal concentration of glucose inside our blood. So what insulin does is it ultimately maintains and regulates a healthy concentration of glucose inside our blood plasma. Now, what exactly is the mechanism by which our insulin actually controls our glucose? Well, basically, under normal conditions, what the insulin does is because it's a peptide hormone, that means it binds onto the membrane of target cells. So the receptor proteins for insulin are found on the plasma membrane of target cells, such as liver cells or muscle cells.