Understanding Insulin: Short-Acting to Long Acting, and Many More

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By : dLife Editors

There are several varieties of insulin, ranging from the short-acting to the long-acting insulin, and many more.  The truth is that all insulin is not the same. Even though all of them help in regulating the blood sugar (blood glucose) levels, each of them has a specific role they play in the process.

Different individuals need certain insulin or combinations of insulin to meet their specific needs.  Your doctor is in the best position to prescribe the type of insulin you need.

However, by learning more about how the different types of insulin work, it becomes easier for you to monitor your response to insulin. This will help you work with your doctor to adjust your treatment plan and hence, help you better control your diabetes.

 What is insulin and How Does it Work?

Insulin is a hormone produced by the pancreas and plays a critical role in our day to day lives. When you eat, the food is broken down and converted into simple sugar (glucose) that moves into your bloodstream.

For the sugars to effectively move from the blood into the cells where they are being used to generate energy, insulins are required.

Without insulin, it becomes very difficult for the sugar to enter into the cells and are thus kept in the bloodstream.

When there is an excess of these sugars in the blood because they couldn’t gain entrance into the cells, they tend to increase the sugar levels in the blood. This is the major issue being faced by people living with diabetes.

Conventionally, insulin was only being used in treating type 1 diabetes where the body is unable to produce enough insulin.

But today, insulin is also being used as an excellent therapy for type 2 diabetes patients as well. This set of people are being faced with a situation where the body is unable to use the insulin it produces effectively.

When insulin is being prescribed, you must inject it into your bloodstream because the acid in the stomach will digest and render it useless if it were swallowed like pills.

Even though early injections used insulin from pigs and cows, modern medicine has now developed synthetic (laboratory-produced) insulin that acts the same way as insulin made in the human pancreas. Today, biosynthetic insulin is used almost exclusively.

 Different Types of Insulin

There are different types of Insulin which are used for treating diabetes. They include:

#1: Rapid-Acting Insulin

Rapid-acting insulin is usually taken just after or before meals for controlling blood sugar spikes. It often begins to work in 10 to 15 minutes, peaks in about 1 hour, and lasts for about 3 to 5 hours.

However, the dose affects the duration of action – so little units can last 3 hours or less, while 20 or 25 units can last up to 5 hours.

#2: Short-Acting Insulin

This covers your insulin requirements during meals. Because it takes a longer time to start working, compared to the rapid-acting insulin, it is used about 30 to 60 minutes before a meal to control the blood sugar levels.

Regular human insulin begins to work in 30 to 60 minutes. Its peak effect occurs in 2 to 3 hours, and it lasts for about 5 to 7 hours.

The major advantage of regular-acting insulin is that you do not have to use it before every meal. It can be taken at supper and breakfast and still work perfectly since it lasts longer.

#3: Intermediate-Acting Insulin

This type of insulin can control the blood sugar levels for up to 12 hours or even more, so it can be taken overnight.

It starts to work within 1 to 3 hours, peaks between 4 to 9 hours and lasts for as long as 12 hours.

Intermediate-acting insulin offers baseline insulin coverage, and it can be used together with rapid-acting insulin and short-acting insulin.

#4: Pre-Mixed Insulin

The pre-mixed insulin combines short- and intermediate-acting insulin. It is usually used before meals twice a day – mostly 15 minutes to 25 minutes before eating.

It begins action within 10 to 45 minutes, and its peak time varies. The duration of action is about 9 to 15 hours.

Pre-mixed insulin is designed for more convenience. But not everyone has the same insulin needs, so they do not fit perfectly into the pre-mixed class.

#5: Long-Acting Insulin Analogs

Long-acting insulin begins action after 1 to 2 hours. Its insulin effect plateaus for the next few hours and then a relatively flat action duration follows, and this lasts for about 15 to 24 hours.

This insulin is often used at bedtime. It offers 24-hour coverage and has been helpful in controlling blood sugar in type 2 diabetes.

Your doctor will determine which insulin type to use depending on your blood sugar levels, lifestyle and whether it’s type 1 or 2 diabetes.


  1. “Short-Acting Insulin,” Retrieved on May 18, 2018.  Available: https://www.diabetes.co.uk/insulin/short-acting-insulin.html
  2. “Long-Acting Insulin,” Retrieved on May 18, 2018.  Available:  https://www.diabetes.co.uk/insulin/long-acting-insulin.html
  3. “What is Insulin,” Retrieved on May 18, 2018.  Available: https://www.endocrineweb.com/conditions/type-1-diabetes/what-insulin.
  4. “Type 1 Diabetes: How is it treated?” Retrieved on May 18, 2018.  Available: https://kidshealth.org/en/teens/treating-type1.html