How Insulin works in the body

•Insulin is a hormone that is secreted by the beta cells of the islets of Langerhans in the Pancreas to mainly act as a “key” that opens up the cells to allow entry of glucose and utilization of glucose as a source of energy.

•There are also manufactured types of insulin that are used by people with diabetes to manage their condition (learn more on our article on Insulin therapy).

•The basal secretion of insulin occurs continuously between meals. A spike in secretion of insulin occurs immediately after a meal (post-pandrial secretion), triggered by the presence of food in the gut. The role of this spike is to lower the high levels of after meal glucose in the blood.

•Additionally, when there is excess glucose in the bloodstream (a condition known as hyperglycemia), insulin acts by promoting the conversion of glucose to glycogen and its storage in the liver, muscles and adipose tissues.

•The stored glycogen can be converted to glucose later and utilized when the body is need of energy. 

•These processes allow for maintenance of normal blood glucose levels.

•In Diabetes where there is; absence of insulin, deficiency of insulin, or insulin resistance (the cells don’t respond as they should to insulin), the body is unable to adequately utilize glucose.This leads to higher levels of glucose in the blood. The condition is known as hyperglycemia. Chronic hyperglycemia is a characteristic of Diabetes mellitus.

•In general, insulin is a hormone that aids in anabolic processes of the body (energy conserving). It promotes the utilization of glucose by the cells to produce energy by moving glucose from your blood to the cells (particularly cells of the liver, muscles and adipose tissues)

Ways in which Insulin Lowers the Blood glucose level

Insulin lowers the level of glucose in the blood by:

  1. Promoting the conver​​sion of glucose to glycogen which is stored and utilized later when the body is need of energy. Another hormone, glucagon, helps in conversion of the stored glycogen to glucose when the body is need of more glucose.
  2. Insulin inhibits the breakdown of fats and proteins to glucose (a process known as gluconeogenesis) in the liver.
  3. Effects on Fat Metabolism.  Insulin promotes entry of free fatty acids into adipose tissues. It also inhibits the breakdown of fats into free fatty acids and triglycerides.Insulin reduces the plasma levels of lipoproteins such a very low density lipoproteins (bad cholesterol). The net effect of these actions leads to reduced risk of accumulation of fats in the blood vessels also referred to as artherosclerosis which can lead to complications such as heart attack and stroke.
  4. Effects on Metabolism of Proteins. Insulin promotes the entry of amino acids into the cell. Amino acids are the building blocks of proteins. In so doing, it promotes protein synthesis from amino acids. Insulin also inhibits breakdown of amino acids to glucose (gluconeogenesis). This helps prevent WASTING (unexplained weight loss- a common symptom in diabetes).

Other functions of Insulin

  • Insulin and Hyperkalemia

Insulin promotes entry of potassium ions into the cell leading to low potassium levels outside the cell (hypokalemia). Therefore it is useful in management of hyperkalemia (high extracellular potassium level). Hyperkalemia may lead to cardiovascular complications.

  • Promoting Growth

Insulin promotes growth and repair by regulating the uptake of amino acids, synthesis of proteins and DNA replication.