All about insulin

All about insulin

What is Insulin?

Insulin is a naturally occurring hormone secreted by the pancreas and it helps the body to use glucose for energy. Glucose is one of the types of sugar present in carbohydrates. An insulin molecule has 51 amino acids. The molecular weight of insulin is 5808 Da. 

Insulin hormone is produced in the cluster of cells in the pancreas called islets of Langerhans. The name Insulin is derived from the Latin word “ Insula” meaning Island. This refers to the cluster of cells (islets) that produces the hormone in the pancreas. 

Insulin also helps in breaking down fats and protein for energy. It is a protein chain or peptide hormone. The structure of insulin varies with different species of animals.

insulin molecule

What does Insulin do?

Some important functions of Insulin are :

  • Insulin regulates blood sugar in the body.
  • Insulin has various ababolic effects on the entire body. 
  • It regulates the intake of amino acids by the body cells.
  • It allows blood glucose to be taken from the cells of the liver, muscle, and fat tissue and converts to glycogen that can be accumulated in the liver and muscles.
  • Insulin prohibits the use of fat as an energy source. In the absence of Insulin, the body uses fat as an energy source instead of glucose.
  • Insulin regulates various body systems. 
  • Insulin also helps in breaking down fats and protein for energy.

insulin molecule

Insulin Secretion

Insulin is produced in specific quantities in the pancreas. It is usually secreted as a response to elevated blood sugar levels. This is done to regulate the blood glucose levels in our body and also control the other senses. 

Insulin is also secreted as a response to taste and sight of food, elevated levels of molecules like amino acids and fatty acids in the blood. 

The higher the levels of glucose, the higher the level of insulin produced to balance the optimum blood sugar level. 

Insulin and diabetes

Before knowing the relation between insulin and diabetes, it is important to know the process of metabolism. After the intake of food, the digestive system breaks down the carbohydrates from the food into glucose. Then, through the lining of the small intestine glucose is absorbed into the bloodstream. Insulin triggers the cells throughout the body to absorb glucose as an energy source. 

Diabetes usually occurs when the above process fails i.e. diabetes prevents the body from properly using the energy from the food ingested. Diabetes occurs due to one of the two different cases:

  • The pancreas secretes inadequate or no insulin at all.
  • The pancreas secretes insulin however the insulin doesn’t work as it’s supposed to. Usually happens when the cells don’t respond well to the action of Insulin. This condition is called Insulin Resistance.

Hence, doctors usually prescribe shots of insulin to diabetes patients. This is very important in the case of type 1 diabetes patients. In Type 1 diabetes, the pancreas secretes inadequate or no insulin at all, therefore sugar couldn’t be used as energy in the cells. The main cause for this is the immune system targets and kills the pancreatic cells where insulin is produced. Therefore, they depend on an external dosage of insulin for their survival.

However, in the case of type 2 diabetes, patients can manage by altering their lifestyle and by intake of oral medication.

Types of Insulin

Doctors usually prescribe different types of Insulin according to the person and the nature of the effect it needs to have. Insulin is classified into various types based on a set of factors. These are:

  • Speed of onset: Expected time for the effects of insulin to start.
  • Peak: Time it takes for the insulin to reach the maximum impact/effect
  • Duration: Time it takes for the effects to wear off
  • Concentration
  • Type or mode of delivery: Whether injected or inhaled or any other means. 

The types of insulin are:

  • Rapid-acting insulin
  • Short-acting insulin
  • Intermediate-acting insulin
  • Long-acting insulin
  • Ultra-long-acting insulin
  • Inhaled Insulin
  • Premixed/ combination of insulin
Type of Insulin Speed of onset(hrs) Duration(hrs) Examples
Ultra-long-acting insulin 6 36 – 42 Tresiba, Toujeo
Long-acting insulin 2 – 4 24 Levemir, Lantus, Basaglar
Intermediate-acting insulin 1 – 2 12 Novolin N
Short-acting insulin 0.5 3 – 6 Novolin R
Rapid-acting insulin 0.25 2 – 4 Novolog, Humalog, Apidra
Inhaled Insulin 12 – 15 mins 3 Afrezza

Premixed Insulin

This type is a mixture of rapid-acting or short-acting insulin combined with intermediate-acting insulin. Hence, eliminating the need to draw insulin from more than one bottle.

Premixed Insulin

How to take insulin dosage?

Patients usually self-administer insulin injections using a syringe. The syringe has markings on its body, it helps to use the correct level of dosage. There are other ways of taking insulin:

  • Insulin Pens: they are more accurate and durable than syringes
  • Insulin pumps: These are attached to a thin tube underneath one’s skin. They are usually motorized or computerized, also acting as a monitor. 
  • Jet Injector: It holds several doses of Insulin
  • Inhalable Insulin: It comes in a premeasured inhaler. It is one of the newly approved methods.

Insulin hormone is very important for the proper functioning of the body. It is necessary for us to stay healthy by making lifestyle and diet changes so that the functioning and production of insulin is proper. Insulin dosage is vital for diabetes patients when the body is unable to produce the same. Doctors usually prescribe them when medications alone can’t keep the blood sugar level under control. 

It is important to know that the type of insulin prescribed depends on various factors and may vary from patient to patient. However, it is better to prevent diabetes from reaching this stage by making appropriate lifestyle changes. 


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