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Rapid-Acting Versus Long-Acting Insulin: What’s the Difference?

by The GoodRx Pharmacist on November 20, 2017 at 4:22 pm

For people who need to take insulin, there are a couple of different typeslong-acting, short-acting, rapid-acting, intermediate-acting, etc. That’s a lot of options!

One question I see most often is the difference between rapid-acting and long-acting insulins. So, let’s get into it.   

What is rapid-acting insulin?

Rapid-acting, or meal-time insulin, is a type of insulin that’s usually taken before, during, or after a meal to lower your blood sugar levels associated with meals. 

Examples of rapid-acting insulins are Humalog, Novolog, Apidra and Afrezza.

How long does it take rapid-acting insulin to begin working?

The onset of action varies between rapid-acting insulin products, but can begin working in as little as 5 minutes, or could take as long as 30 minutes, depending on the insulin.

The following are the typical onset of action times for each individual rapid-acting insulin products.

What is long-acting insulin?

Long-acting, or basal insulin, is a type of insulin that gives you a slow steady release of insulin that helps control your blood sugar between meals, and overnight.

Common long-acting insulins include Lantus, Basaglar, and Levemir.

How long does long-acting insulin last?

The duration of action varies between long-acting products but should last anywhere between 22-24 hours. The following are the typical duration of action times for each individual long-acting insulin product:

Do I need more than one insulin?

Maybe. It’s up to your doctor to determine the best medication regimen for you.

Some type 2 diabetes patients may only need to use a long-acting insulin to get their blood sugar control on track; whereas others may need a combination of meal-time and long-acting insulin to best control their blood sugar.

If you are using an insulin pump, you will only need to use a rapid or short-acting insulin. The pump is able to give you a slow and steady amount of insulin to cover you all day like a long-acting insulin would do. However, it’s a good idea to have a back-up of long-acting insulin on hand in case your pump should fail.

Is there anything in between rapid-acting and long-acting?

Yes. There are short-acting and intermediate-acting insulins available.  

  • Short-acting insulins are used like rapid-acting insulin to cover blood sugar elevation from eating.  
  • Intermediate-acting insulins are similar to long-acting insulins as they are used to cover blood sugar elevations when the rapid-acting or short-acting insulins finish working.    

Are there any combination options available for those who don’t want to inject themselves so often?

Yes. Some insulin products combine fast and longer-acting insulins that work together to help manage blood sugar between meals and at night, as well as blood sugar “spikes” that happen when you eat. Here are a few examples of these:

Combination insulin products typically only need to be injected twice daily since they are single insulin products that work in 2 ways.  

Are there any insulin products that last longer than long-acting insulins?

Yes. There are 2 ultra-long-acting insulin products that are available—Toujeo and Tresiba.

The ultra-long-acting insulin, Toujeo, was approved by the FDA in February 2015.  Toujeo will begin working within 6 hours of injecting and last for 36 hours with no peak.  

The ultra-long-acting insulin, Tresiba, was approved by the FDA in September 2015.  Tresiba will begin working within 1 hour of injecting and last at least 42 hours with no peak.  

Does all insulin need to be injected?

No. Currently, there’s 1 rapid-acting insulin product, Afrezza, that’s inhaled through the mouth.  


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