Insulin: Function and types

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What is insulin?

Insulin is a hormone secreted by the pancreas, a gland found near the stomach. Insulin helps glucose efficiently enter the bloodstream of the body. Glucose is nothing but a sugar present in carbohydrates. Lack of Insulin in the body reduces the problems related to Diabetes. It helps to balance the blood glucose levels of the body. Insulin stores additional glucose in the liver, fat and muscles, and it also regulates fats, proteins and the metabolism of carbohydrates.

Insulin tells the body to store remaining glucose in the liver when there is an excess of glucose in the bloodstream. The leftover glucose is not released until there is a significant drop in the blood glucose level of the body. Your glucose level drops when your body is stressed and needs an extra dose of energy.

Main functions of insulin 

  • Modifies the activities of enzyme
  • Builds muscle despite injury or sickness
  • Manages the lipid synthesis
  • Manages the breakdown of proteins and lipids
  • Manages excess excretion of sodium
  • Enhances memory and learning capability

Types of Insulin

There are different insulin available for the treatment of Diabetes.  

Rapid-acting Insulin

Rapid-acting Insulins generally start to work in 15 minutes. It may last for 3 to 5 hours. Some popular examples are Insulin Lispro, Insulin Aspart and Insulin glulisine.

Short-acting Insulin 

Short-acting insulin starts to work in 30 to 60 minutes. It may last 5 to 8 hours. Regular insulin is the best example of this insulin.

Intermediate-acting Insulin

This insulin commences its work in 1 to 3 hours and may last 12 to 16 hours—for example, Insulin NPH.

Long-acting Insulin

This insulin starts working in 1 hour and may last 20 to 26 hours. Some of the famous examples of Long-acting Insulin are Insulin glargine and insulin detemir.

Pre-mixed Insulin

Pre-mixed Insulins are combinations of two types of insulin. Usually, Rapid/short-acting insulin and intermediate-acting insulin are used in the pre-mixed type.

Characteristics of Insulin

Insulin is primarily used for the treatment of Diabetes. Insulin is fundamentally classified based on its speed and how long it performs on the body. It is classified into three types, namely onset, peak time and duration.

Onset – This is classified based on how fast the insulin drops the count of the blood sugar.  

Peak-time – Time taken for the insulin to achieve its maximum capacity.

Duration – Time taken for the insulin to lower the body sugar  

Your doctor may prescribe insulin after examining your body’s condition and performance. Some of the things your doctor notices during the examination include:

  • Foods you eat
  • How active your body is
  • How your body manages the sugar
  • Your age
  • Time taken by your body to absorb the insulin

For example, if you are diagnosed with type 1 Diabetes, you may need a combination of any insulins.  

Insulin is also recommended if you are diagnosed with type 2 Diabetes.

It is essential to follow your doctor’s advice regarding the dosing information. Brands that produce insulin may vary in all the formats like onset, peak time and duration.  

Insulin strength

Typically, Insulins are made at different strengths and capacities. In general, the strength of the insulin is usually U-100. In other words, 100 units of insulin in one milliliter of fluid. It is also available in U-500. This is 5 times more concentrated than U-100 insulin. Some types of Insulins are fast working and last for a shorter period of time, while some insulins are slow in working and last for longer periods.  

Insulin delivery Options

Insulin can be taken in four major ways:

  • Insulin pen
  • Insulin syringe
  • Insulin pump
  • Insulin inhaler

Insulin pen

Insulin pens are recommended for children as they would be convenient and comfortable during the injection. Cartridges are inserted in the case of Insulin pens. Insulin doses are dialed in pen and are inserted through the needle into the human body.

Insulin syringe 

A syringe is often preferred for the ingestion of insulin. Most of cases, smaller capacity syringes are used because of their unaltered accuracy.

Advantages of Insulin syringes and pen

  • Injections often require less training
  • Lower cost
  • Provides more flexibility
  • Improvises physical and psychological well-being

Insulin inhaler

In this case, insulin is taken as an oral inhaler to deliver ultra-rapid-acting insulin before meals. This insulin is used with injectable long-acting insulin.


  • It is not an injection
  • Lowers the risk of blood sugar levels
  • Causes less weight gain
  • Can be consumed at the beginning of the meals

Insulin pump 

The insulin pump resembles the size of a small cell phone. It gives a basal dose of rapid-acting insulin per hour. When your blood sugar level is high, you need to calculate the dose, and insulin present in the pump delivers the bolus.  

Advantages of Insulin pump 

  • Delivers insulin with accuracy
  • Deliver bolus insulin easier
  • Eliminates side effects of insulin

Role of insulin in the body 

Insulin plays a vital role in the functioning of the body. It provides energy and helps to normalise high blood sugar levels.

Regulates blood sugar levels 

The most crucial role of insulin in the human body is, that it helps to regulate blood sugar levels. It interacts with glucose to enter human cells to produce energy for the body. The pancreas is the vital reason for the production of insulin hormones. Insulin helps to open the body cells and use that as a source of energy.

Store excess glucose for energy

There is a condition called Hyperglycemia, where extra glucose is deposited in the bloodstream. In these cases, insulin helps to store the extra glucose in the form of glycogen in the muscle, liver and fat cells.  

These are later used in the condition whenever energy is required. Due to this, blood glucose levels are restored, and insulin level is stabilised. It helps in the synthesis of glycogen in the liver.

What causes someone to prescribe insulin?  

Insulin is prescribed to a person only when the blood sugar level of the person is high. By injecting insulin, the blood sugar level of the person is diminished and brought to normalcy. Thus, the risk factors and the complications a person might face due to high blood sugar like Diabetes, Hypertension, heart attack and cardiac arrest are prevented.  

However, the injection of insulin varies from person to person and the doctor has to prescribe the dosage details and the amount of time it has to be administered to his/her patient. In most cases, Diabetes is said to be the major course of the reason for the injection of insulin.  

People with Type 1 diabetes and a few with Type 2 Diabetes require Insulin.Therefore, insulin is the best medicine to control your blood sugar levels and makes you healthy.

How do you take insulin?

The most common way of intaking insulin is Subcutaneous insulin injections. A person can intake insulins through an insulin syringe, insulin pen, insulin pumps and vials. Insulin can be injected into the body via the abdomen, upper arm, lower back, hips and buttocks.  

Following are the ways to inject insulin into your body:

  • Gently pinch the skin and insert the needle at an angle of 45 degrees.
  • If your skin tissues are hard, insert the needle at an angle of 90 degrees.
  • Now, push the needle into the skin.
  • After injection, rub your skin gently with cotton.  

Goals of Insulin therapy

The main objective of Insulin therapy is to keep your blood sugar level in the normal range. Keeping blood sugar in control ensures stable health for the body. Generally, Insulin therapy is recommended for people with type 1 and type 2 Diabetes. Through the aid of Insulin therapy, a Diabetes patient’s blood sugar level is normalised, and the complications and risk factors that occur due to high blood sugar levels are diminished.

Summing up

Insulin is a pivotal hormone that helps to produce energy as well as break down fats and proteins. The resistance of insulin increases when lesser cells respond to insulin instructions.  

People can avail themselves of insulin shots to avoid the effects of insulin resistance. Insulins are fast and long-acting; they are carefully prescribed to patients after examining their medical conditions and blood sugar levels.  

Insulin is the best and most reliable for people who want to lower their body’s blood sugar levels.


1. What does insulin do in the body?  

Insulin is a hormone that allows glucose to enter human cells to produce energy.

2.What is insulin for Diabetes?

Insulin is produced by the Beta cells of the pancreas. Insulin helps to keep the blood glucose level stable within the normal range.

3.Why do you need insulin?

Insulin is needed for people who have type 1 and type 2 Diabetes to normalise and control their blood sugar levels.

4. Why is insulin so expensive?  

The main reason why insulin is so expensive is that they are biologics. Biologics are compiled of large and complex compounds, making it harder to develop generics. Due to this, manufacturers determine the cost based on the production.

5. What is an insulin index?

Insulin index represents the hike of insulin concentration present in the blood during the 2-h period after the digestion of the food.

6.What is an insulin resistance diet? 

Insulin resistance occurs when your body cells have a problem responding to insulin. An insulin resistance diet helps to defend against the resistance and normalise the flow of insulin to the body. Some of the insulin resistance diets are vegetarian, low fat, low carb, Mediterranean diet, etc.


The Information including but not limited to text, graphics, images and other material contained on this blog are intended for education and awareness only. No material on this blog is intended to be a substitute for professional medical help including diagnosis or treatment. It is always advisable to consult medical professional before relying on the content. Neither the Author nor Star Health and Allied Insurance Co. Ltd accepts any responsibility for any potential risk to any visitor/reader.

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