Fiasp Insulin, Insulin Aspart, Fiasp vs Novolog - Doctablet®

Fiasp Insulin, Insulin Aspart, Fiasp vs Novolog

Doctablet Diabetes, Everything About Insulin

Fast Acting Insulin: Fiasp is Faster than Novolog


It’s understandable if you are wondering what Fiasp insulin is. The truth is, we were wondering the same thing when the FDA announced its approval of Novo Nordisk’s new, first in class, injectable, “faster-acting” insulin. What do we mean by faster-acting insulin? Well, now there are two levels of fast when it comes to mealtime (rapid-acting) insulin: Fast and Faster.

Fast vs Faster-acting insulin injections

Fast Acting Insulins

Faster Acting Insulin

Insulin Name

Humalog® (insulin lispro)

Novolog® (insulin aspart)

Apidra® (insulin glulisine)

Fiasp® (insulin aspart)

Timing of Dose

Within 15 minutes before meal

(Within 20 minutes after starting a meal for Apidra® only)

Up to 2 minutes before a meal

Up to 20 minutes after starting a meal

Onset of action

10 to 20 minutes

2.5 to 4 minutes

Duration of action

3 to 5 hours

3 to 5 hours

Insulin aspart is a powerhouse in the world of diabetes. It was introduced under the brand name Novolog in June of 2000. For over 15 years, Novolog has been a staple of insulin regimens for many patients. Novolog and Humalog are the two most commonly prescribed fast-acting insulins that patients take within 15 minutes of mealtime. For this article, we will be paying closer attention to insulin aspart (more commonly called Novolog or Novorapid® in Europe and Canada). Novolog itself is an insulin analogue. This means it has been modified from regular insulin to change its structure and how quickly it is absorbed from under the skin.

Novo Nordisk teamed up their workhorse Novolog insulin with a B3 vitamin (nicotinamide) to make it absorb more quickly and the amino acid arginine to stabilize it. That’s right! Fiasp insulin is simply Novolog with two small additions: Vitamin B3 and naturally occurring arginine. Researchers discovered that adding nicotinamide to the insulin aspart molecule causes its initial absorption to happen more quickly. This means it acts more like the insulin normally made by your pancreas. Fiasp insulin can even be taken up to 20 minutes AFTER starting the meal! So if Fiasp were racing Novolog, it could give Novolog a 15-minute head start and still catch up! Not only that, but twice as much insulin is available within 30 minutes of injecting Fiasp as compared to Novolog. More insulin available earlier means more insulin is in the body to handle the sugar entering your blood stream after eating. So what are the key differences between Novolog and Fiasp? Here is a quick summary:

Novolog vs Fiasp: Same insulin aspart plus Vitamin D

Novolog vs. Fiasp

Novolog® (insulin aspart)

Fiasp® (insulin aspart)

Year released



Fast-acting mealtime insulin
Faster-acting mealtime insulin

Onset of action

10-20 minutes
4 minutes

Injection frequency

Within 15 minutes of the meal
Beginning of meal, up to 20 minutes after

Duration of action

3 to 5 hours
3 to 5 hours

Differences vs. regular insulin

Amino acid substitution
Amino acid substitution

Added nicotinamide for faster absorption and L-arginine for stability


$564 per month
(0.38 cents per unit)
Pricing has not been finalized in the USA

Common questions about Fiasp® Insulin

Insulin Apart is present in both Fiasp and Novolog
How long does Fiasp last in the body?

Fiasp is in a class of insulin called “faster-acting” insulin. Fiasp’s onset to action is approximately 4 minutes. The half-life of Fiasp is 1 hour, and it lasts about 4 hours in the body. By adding a vitamin B3 to insulin aspart (Novolog), the initial absorption is quicker and the amount of insulin available doubles in the half hour after the injection. This allows Fiasp to be used even after you start eating.

Should I lower my insulin dose when I change from Novolog to Fiasp?

Despite the fact that Fiasp has a faster action than Novolog, it is converted on a 1:1 basis. Meaning if you are on 5 units of Novolog and your doctor changes you to Fiasp, your dose will likely still be 5 units.  Close fingerstick glucose monitoring is always recommended when changing between mealtime insulins. While you might start at the same dose, studies suggest improved after-meal blood sugars in those with Type 1 diabetes, in those with Type 1 diabetes on insulin pumps, and improved blood sugars 1 hour after eating in those with type 2 diabetes when patients take Fiasp as compared to Novolog.

What will happen to my HgbA1c if I change to Fiasp?

Studies show that the hemoglobin A1c (HgbA1c, A1c) drop on Fiasp is similar to Novolog both for patients with Type 1 diabetes as well as in those with Type 2 diabetes.

How much insulin does the Fiasp FlexTouch® Pen contain? (vs. Novolog)

The Fiasp FlexTouch pen contains 300 units of insulin, the same amount as the Novolog FlexPen

How many pens are in a box of Fiasp? (vs. Novolog)

The Fiasp FlexTouch pens come 5 in a carton (the same as the Novolog FlexPen).

How should the Fiasp pen be stored?

Both Fiasp and Novolog pens contain the same insulin (aspart) and are stored in a similar way. Insulin pens that have not been used should be kept in the refrigerator. After the first use, both Fiasp and Novolog can be kept at room temperature. Both the Fiasp FlexTouch and Novolog FlexPen should be discarded 28 days after the first injection.

Can Fiasp be used in pregnancy?

Fiasp is insulin aspart, and therefore has the same indication as Novolog in pregnancy. There is no known risk of fetal harm associated with insulin aspart in human studies.

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Last Modified: Sep 17, 2018 @ 5:55 pm
About the Author

Chris Palmeiro D.O. M.Sc.


Dr. Palmeiro is Chairman of Endocrinology at the HealthAlliance of the Hudson Valley, he also serves patients with intellectual and developmental disabilities at the Westchester Institute of Human Development in Valhalla, New York. He has a Masters of Science degree in clinical nutrition and is a diplomate of the American Board of Internal Medicine. His interests within the realm of endocrinology include nutrition support, obesity counseling and the progressive management of diabetes.

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