Lg Cwd

Ultra Rapid Insulins Used in Insulin Pumps

March 24, 2021

Written and clinically reviewed by Marissa Town, RN, BSN, CDCES

One of the barriers to achieving “optimal glycemic control” is having insulin that works fast enough to match the absorption of foods. The rapid acting insulins that we currently have available take 20-30 minutes to be absorbed into the blood stream. In order to try and match the absorption of the food eaten, people with diabetes are encouraged to take their insulin ahead of time, know exactly what and how much they are going to eat, and hope that the timing and calculations work out. This is commonly referred to as pre-bolusing.

The insulin companies have been working to create insulins that are even faster, calling them “ultra-rapid.” These insulins have been available in the United States, for some time with the Novo Nordisk ultra-rapid aspart Fiasp available since 2017, and Eli Lilly’s ultra-rapid lispro Lyumjev, which came to market in June 2020. However, it was not until 2019 that the aspart Fiasp was approved for use in insulin pumps1 and just in January 2020 for use in pediatrics.2

It’s pretty typical for there to be some early adopters of new things, including new technologies or medications, and then for the masses to start utilizing the tools after seeing how things went for the early adopters. There are discussions in diabetes groups and social media channels about people’s off-label personal experiments.

And now studies are being published that show what the early adopters have been saying: the ultra-rapid insulins work just as well as the compared rapid acting.3-5 One study looked at 19 participants using a hybrid closed loop system and concluded that ultra-rapid aspart (Fiasp) compared to aspart (NovoLog) showed similar glycemic outcomes but a small increase in daily insulin needs when using the ultra-rapid.3

Of note, in two randomized controlled trials, there were many patients who experienced a need to change their infusion set early.4-5 The largest of these studies, which included 432 participants, showed that the biggest difference between the ultra-rapid insulin and rapid insulin was the unplanned infusion set changes due to infusion site reactions.4

The good news is that the ultra-rapid insulin did help lower the after-meal (post-prandial) blood sugars from 30 minutes to 3 hours after eating.4 The participants also stayed in the studies despite the infusion site reactions: 94% of the 49 participants in the PRONTO-Pump study and 92.6% of the larger 432 participant study.4-5 This shows that despite these challenges it may still be worth it to use these insulins.

It’s exciting to see the diabetes community and research teams alike working towards the same goals of improving care for people with diabetes and demonstrating safety and efficacy.  The CWD team is encouraged by all of this community progress!


  1. https://www.empr.com/home/news/fiasp-approved-for-use-in-insulin-infusion-pumps/
  2. https://diatribe.org/fda-approves-fiasp-quick-mealtime-insulin-children
  3. https://www.liebertpub.com/doi/pdf/10.1089/dia.2020.0083
  4. https://dom-pubs.onlinelibrary.wiley.com/doi/10.1111/dom.14368
  5. https://www.liebertpub.com/doi/10.1089/dia.2020.0224?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed