Insulin Decreases the Blood Glucose Level

Insulin is a hormone which enhances the rate of glucose uptake by cells, to produce ATP.

When the blood glucose level rises (for example, after a meal is consumed) insulin is released into the bloodstream to lower the level. It also stimulates the liver to convert glucose to glycogen, which is then stored in cells for later use.

Insulin increases glucose transport into certain cells, such as muscle cells and the liver cells. This happens via an insulin-mediated increase in the number of glucose transporter proteins in cell membranes, which remove glucose from circulation by facilitated diffusion. As insulin binds to its target cell via insulin receptors and signal transduction, it triggers the cell to incorporate glucose transport proteins into its membrane. This allows glucose to enter the cell, where it can be used as an energy source. However, this does not occur in all cells: some cells, including those in the kidneys and brain, can access glucose without the use of insulin.

Insulin also stimulates the conversion of glucose to fat in adipocytes and the synthesis of proteins. These actions mediated by insulin cause the blood glucose concentration to fall, called a hypoglycemic “low sugar” effect, which inhibits further insulin release from beta cells through a negative feedback loop.

Impaired insulin function can lead to a condition called diabetes mellitus.