Diabetes Management

What Is Insulin Therapy?

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By Apollo 24|7, Published on - 28 November 2020, Updated on - 28 March 2024

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Insulin therapy is designed to mimic the function of natural insulin produced by the pancreas. The pancreas of people affected with diabetes either does not produce insulin (type 1 diabetes) or does not respond well to insulin (type 2 diabetes). Hence, insulin therapy is prescribed for some of them.
Supplemental insulin is available in many types based on the requirements. Some types of insulin work quickly, while some work slowly. Some may require just one type of insulin, while others may require multiple types. With the right insulin regimen, people with diabetes can reach the individualized target blood sugar levels.
The effective use of insulin requires a basic understanding of the different types available, the duration of action, calculation of the insulin dose, and proper storage.

Types of Insulin

The hormone insulin is released by the pancreas as either bolus or basal, depending on the body’s need.
  • Bolus insulin is released as a response to food intake to keep the glucose levels under control following a meal. Since people with diabetes cannot produce or utilize insulin effectively, a bolus dose of insulin is prescribed. Short-acting or rapid-acting insulins serve the purpose of keeping the blood glucose in check after a meal.

  • Rapid-acting insulin - It is used to minimize the surge in blood sugar immediately after a meal or snack.

  • Short-acting insulin - Also known as regular or neutral insulin, it controls postprandial blood glucose levels.

  • Basal insulin, also called background insulin, regulates glucose levels between meals irrespective of food intake. It is released continuously throughout the day and night. A basal dose of insulin is required to act over a long period, and the types are intermediate, long-acting, or ultra-long-acting insulin. These help to regulate blood sugar levels throughout the day, between meals, and at night while fasting.

Insulin is classified into various types based on three characteristics:
  1. Onset: It is the time taken for insulin to enter the bloodstream and start lowering blood sugar.

  2. Peak time: This refers to the period during which insulin works most effectively.

  3. Duration: It is the period of time during which the insulin continues to act.

Based on the action or the speed at which they work, insulin can be categorized as:
  • Intermediate-acting insulin - Also referred to as isophane or NPH insulin, it is usually taken in conjunction with short-acting insulin. This is suitable for people who experience a spike in blood sugar during the night and morning.

  • Long-acting insulin - It is active throughout the day and is suitable for people with high blood sugar during the day and overnight. It primarily functions to reduce the fasting blood glucose level.

  • Ultra-long-acting insulin - It has a prolonged release and shows a glucose-lowering effect for up to 42 hours.

Bolus insulin


Rapid-acting insulin

Short-acting insulin


15 minutes

30 minutes

Peak time

1 - 2 hours

2 - 3 hours


2 - 4 hours

3 - 6 hours

Time of injection

Just before the meal

Little before the meal


Basal insulin


Intermediate-acting insulin

 Long-acting insulin

Ultra-long-acting insulin


2 to 4 hours

Several hours

6 hours

Peak time

4 to 12 hours

Throughout the day

No peak time


12 to 18 hours

24 hours or longer

36 hours or longer

Time of injection

Once a day at bedtime or twice a day not specific to mealtime

Once a day at bedtime or twice a day not specific to mealtime

Once a day or 3 times a week

Other types of insulin include premixed insulin and inhaled insulin.
    • Premixed insulins are preparations of rapid-acting insulin with either intermediate or long-acting insulin.

    • Inhaled insulin is rapid-acting insulin inhaled at the beginning of the meal, and this type is always used in combination with injectable long-acting insulin.

How insulin is used

Your doctor will help recommend the best insulin regimen based on your individualized need and considering various aspects – the type of diabetes, hbA1c readings, your age, weight, years lived with diabetes, blood sugar levels, etc.
  • Once-daily insulin regimen: This is suitable for people with type 2 diabetes requiring assistance in taking injections. The regimen involves taking long-acting insulin or intermediate type insulin along with medications.

  • Twice-daily regimen: Suitable for both type 1 and type 2 diabetes, this regimen involves taking a mixture of short-acting and intermediate-acting insulin. They can be mixed manually or taken as pre-mixed insulin.

  • Basal-bolus regimen/multiple daily injection therapy: This regimen involves taking both basal and bolus insulins. Basal insulin is taken once or twice daily and separate bolus injections at each meal. It is commonly used in people with type 1 diabetes, and sometimes in type 2 diabetes. Basal-bolus regimen allows flexibility with mealtimes, and one can vary the dose based on the carbohydrate intake.

  • Insulin pump therapy/continuous subcutaneous insulin infusion: An insulin pump is connected to the body to deliver insulin. It delivers basal insulin continuously throughout the day and bolus insulin on demand when food is consumed. It is generally used for type 1 diabetes in people unable to manage high blood sugar with multiple injections.

Calculation of insulin requirement

Although the doctor provides an insulin dose regimen, sometimes it is useful to be aware of the daily insulin requirement. The general calculation used for the total daily amount of insulin (TDI) required in units = Bodyweight in pounds ÷ 4.

Tips for storing insulin

Improper storage can lead to insulin breakdown affecting its ability to efficiently control blood sugar. Here are a few tips on how to store insulin for maximum efficacy:
  • Store all supplies in the refrigerator.

  • Avoid storing insulin in extremely hot or cold temperatures.

  • Store the opened insulin bottle at room temperature (up to one month) as injecting cold insulin can be painful.

  • Never expose insulin to direct sunlight.

  • Check the expiration date and never use expired insulin.

  • Always check the bottle before each use and make sure the insulin looks normal without any particles, crystals, discolouration, or frosting.


Insulin shots are essential for managing type 1 and sometimes type 2 diabetes. Insulin is given based on how quickly the blood sugar levels must drop, and the duration for which these levels have to be maintained. The insulin prescribed depends on the characteristics of a particular type of insulin aligned to the specific needs of a diabetic person. The need to take insulin to control blood sugar may be daunting but becomes comfortable gradually. However, it may take some time to find the right insulin regimen to reach the target blood sugar levels.
For any queries related to diabetes, speak to an endocrinologist or a diabetologist. 


Diabetes Management

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