Insulin's Role in the Human Body

Insulin is a hormone produced by the pancreas that has a number of important functions in the human body, particularly in the control of blood glucose levels and preventing hyperglycemia. Insulin also has an effect on several other areas of the body, including the synthesis of lipids and regulation of enzymatic activity.

How does insulin work?

Image Credit: Designua /

Insulin and metabolic processes

The most important role of insulin in the human body is its interaction with glucose to allow the cells of the body to use glucose as energy. The pancreas usually produces more insulin in response to a spike in blood sugar levels, as occurs after eating a meal, for example. This is because insulin acts as a “key” to open up the cells in the body to allow for glucose to be used as an energy source.  

Additionally, when there is excess glucose in the bloodstream, which is a condition known as hyperglycemia, insulin encourages the storage of glucose as glycogen in the liver, muscle, and fat cells. These stores can then be used at a later date when energy requirements are higher. As a result of this, there is less insulin in the bloodstream, and normal blood glucose levels are restored.

Insulin stimulates the synthesis of glycogen in the liver; however, when the liver is saturated with glycogen, an alternative pathway takes over. This involves the uptake of additional glucose into adipose tissue, leading to the synthesis of lipoproteins.

Effect of Insulin on glucose uptakeImage Credit: Alila Medical Media /

Results without insulin

In the absence of insulin, the body is not able to utilize glucose as energy in the cells. As a result, the glucose remains in the bloodstream and can lead to hyperglycemia. Chronic hyperglycemia is characteristic of diabetes mellitus and, if untreated, is associated with severe complications, such as damage to the nervous system, eyes, kidneys, and extremities.

In severe cases, lack of insulin and a reduced ability to use glucose as a source of energy can lead to a reliance on fat stores as the sole source of energy. The breakdown of these fats can release ketones into the bloodstream, which can lead to a serious condition called ketoacidosis.

Other functions of insulin

In addition to the regulation of glucose, insulin also plays a role in other areas of the body. To this end, insulin may be involved in:

  • Modifying the activity of enzymes and the resulting reactions in the body.
  • Building muscle following sickness or injury via the transportation of amino acids to the muscle tissue, which is required to repair muscular damage and increase size and strength. It helps to regulate the uptake of amino acids, DNA replication, and the synthesis of proteins.
  • Managing the synthesis of lipids by uptake into fat cells, which are converted to triglycerides.
  • Managing breakdown of protein and lipids due to changes in fat cells.
  • Uptake of amino acids and potassium into the cells that cannot take place in the absence of insulin.
  • Managing the excretion of sodium and fluid volume in the urine.
  • Enhancing the memory and learning capabilities of the brain.

It is evident that insulin plays a number of essential roles in the body, including the management of sugar levels in the blood and many other areas.


Further Reading

Last Updated: Mar 30, 2021

Yolanda Smith

Written by

Yolanda Smith

Yolanda graduated with a Bachelor of Pharmacy at the University of South Australia and has experience working in both Australia and Italy. She is passionate about how medicine, diet and lifestyle affect our health and enjoys helping people understand this. In her spare time she loves to explore the world and learn about new cultures and languages.


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  1. Major Mayhem Major Mayhem Australia says:

    This is an incomplete description of insulin and diabetes. This article only address Type 1 diabetes where the insulin is lacking due to pancreatic insufficiency.
    In type 2 diabetes, the opposite happens. There is too much insulin in response to high blood glucose, the cells response by increasing resistance to the insulin or become de-sensitized to the insulin. The pancreas then responded by increasing insulin production even more and the cells responded by increasing insulin resistance even more. It becomes a tug o war game between the pancreas and the cells.

    Because insulin cannot push glucose into cells due to insulin resistance nature of the cells. The insulin has no choice but store glucose in the blood as glycogen in the liver and adipose tissue. It creates the paradoxical effect where, the cells are starving for glucose and cannot produce energy but the liver is turning fatty from glycogen over-store and adipose tissue is expanding.

    • Pat Thomas Pat Thomas United States says:

      The medical industry and the nutrition industry are still sheltering low nutrient carbohydrates.... are these industries really that ignorant?????

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
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