Insulin and Types Of Insulin

It was the year 1921, when Dr Frederick Banting, a Canadian physician/scientist along with a medical student Charles Best made a breakthrough discovery in the field of medicine. This changed the perception about diabetes, earlier thought to be a fatal disease and for the first time there was belief that this disease could be contained.

Yes, you guessed it right, the discovery we are talking about is Insulin.

Insulin is a protein hormone which is secreted from the Beta cells located in the islets of the Pancreas.

It’s main function is the tight regulation of blood glucose in our body.


Insulin is a protein hormone. It is made up of 51 amino acids or peptides (building blocks of a protein) and has 3 chains – the A chain, the B chain and the C chain.

Initially it is secreted as a pro hormone, which is an inactive form of the hormone. This is then activated to insulin, which then goes on to perform its function.

How Does Insulin Work?

Once blood glucose level rises in the body, the beta cells in the pancreas senses this. Once this has occurred, some chemical mediators lead to the release of insulin into the bloodstream.

Once it is released into the bloodstream, it binds to insulin receptors located on various cells. The binding of insulin to the cells helps glucose enter them to provide energy.

After the action of insulin is complete, it is destroyed in the liver or the kidney.

There are two phases involving the release of Insulin

In the first phase, insulin is released rapidly in response to a rise in blood sugar level. This effect lasts for a period of about 10 minutes In the second phase, insulin is released independent of blood sugar levels and this effect lasts for a period of about 5-6 hours.

So what does insulin do?

Insulin allows transport of blood glucose  into the cells, a majority of them being muscle cells and fat cells. In the muscle cells glucose is utilised for energy purposes and for the proper functioning of a muscle.

For example, during exercise, our muscles require glucose as its energy source, without which we would end up with frequent cramps.

In the fat cells, glucose is stored for future use. For example, during starvation, the blood glucose levels become very low. In order to produce energy, the fat cells are broken down into glucose and supplies the energy that  the body needs.

In addition to this, insulin has a number of other roles –

1. It decreases the breakdown of protein in the body

2. It decreases the breakdown of fats in the body

3. It allows the storage of glucose in the liver cells as glycogen. Glycogen is broken down into glucose when the body needs it.

4. It allows the movement of potassium within the cells, which is essential for adequate functioning of cells and tissues in the body.

Diabetes and Insulin

There are 2 main types of diabetes – type 1 and type 2.

In type 1 diabetes, the body does not produce insulin. Insulin injections are the only treatment in type 1 diabetes.

In type 2 diabetes, insulin is produced in very minimal amounts by the pancreas.  Alternatively, the cells do not respond to the insulin that is being secreted. Insulin is often used later in type 2 diabetes. Tablets remain the first treatments given.

When insulin was first discovered and used in clinical practice, they were derived from cow and pig pancreas. However, clinical research has advanced a great deal over the years, and insulin is now derived from human samples.

As of now, insulin can only be injected under the skin or into a vein. However, newer insulins are emerging that can be inhaled. Insulin tablets are not available as they get destroyed by the digestive juices in the stomach.

Types of Insulin

There are various types of insulin injections depending upon its time of action.

Rapid Acting Insulin

This type of insulin begins to work 15-20 minutes after an injection and it’s effect lasts for 2-3 hours.It is usually combined with a longer acting insulin.

Short Acting Insulin

This type of insulin begins to work 30 minutes after an injection and it’s effect lasts for about 3-6 hours.

Intermediate Acting Insulin

This type of insulin begins to work 2-4 hours after an injection and it’s effect lasts for about 12-18 hours.

Long Acting Insulin

This type of insulin begins to work several hours after an injection and it’s effect lasts for up to 24 hours. It acts slowly and keeps blood sugar controlled in a gentle manner.

Insulin dosage has to be administered as if it was being naturally produced by the body.

Hence, before meals a short acting or a rapid acting insulin can be given to counter the surge in blood sugar levels similar to the Phase 1 release of insulin and a intermediate or a long acting insulin can be given once/twice a day to maintain baseline insulin levels in the blood.

Inhaled Insulin

Recently, research discovered an insulin that can exert its effects when inhaled. Inhaled insulins are rapid acting and work within 10 – 15 minutes of use. However, their effect only lasts around 3 hours. For this reason, it is often combined with a long acting insulin.


Insulins are of many types. When your doctor prescribes your insulin, it may be a combination of 2 or just a single type.

Don’t worry about your insulin or the type of insulin you are taking. As long as your sugars are controlled, just continue with your diet and exercise plan when taking insulin. Your doctor will guide you on how to keep your blood sugars in check.

Remember, being on insulin can be a good thing. It allows you to get better control of your sugars.

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