Does #Fiasp equal Freedom? A round up of collective experiences

As I’ve mentioned plenty of times, I’ve been using Fiasp in a Closed Loop for some time, and the last week or so has really seen it coming into it’s own in terms of the distribution of my glucose levels. This last week is a case in point, and I’m of the opinion that this stuff works extremely well in a closed loop system.

But I’m not the only one that’s using this stuff. There are plenty of others. And their voices are also worth hearing. Using data from those who have filled this form in, providing this data set, plus feedback from and facebook groups, we see the following

  1. It acts faster than both NovoRapid and Lispro. For those for whom it works, the time before a meal that is required for pre-bolusing is dropped, in most cases to between zero and ten minutes. For me personally, bolusing with food works very well, so it’s good to see this result from others.
  2. It IS being seen to be faster than Humalog for some. We hear from some HCPs that they are only going to change those who are on NovoRapid, however, the feedback from the small sample set that is given suggests that many humalog users would benefit:
    • “I’m impressed with Fiasp and think it’s a great step forward from Humalog.”
    • “Works much better than Lispro. Less Insulin Doses (ca. 3/4). Shorter “”Injekt-Eat-Distance”” (20 to 45 minutes). Shorter Duration of Action (ca. 4 instad 5 hrs.).”
    • “Action time is ~15mins faster than Humalog, great for bolusing during/end of meal. Really cuts down on post meal spikes.”
  3. There is a lack of clarity as to how to handle the tail – whilst it is not that different in theory to NovoRapid, people are getting different experiences of it. Some are using the same period as Novorapid/Humalog whilst others have shortened their DIA.
  4. Careful monitoring after changing is really important.
  5. Some people see increased resistance to Fiasp around breakfast time, in line with Dawn Phenomenon issues.
  6. Localised red bumps have been seen at some cannula sites, raising some concerns about micro scarring, and a couple of people have reduced their cannula life as a result.
  7. Whilst most users are happy with the faster onset, some have not seen this effect and still get results that are in line with Novorapid, but see the peak occurring with more impact.
  8. There are a few for whom it simply doesn’t seem to have an effect, and who have given up.

To quote a participant on,

Well FIASP is a god send for spontaneous eating, I kinda of winged it today at the street food event. Got there for 11am, mentally prepared my self to not get stressed at a double digit. From 11am til 2:30 I ate:

Fried Chicken and Fries, Soft Tacos, Fish and Rice, Half a Pizza and a ended with a creme brulee. And to drink two beers. I set a high basal to cover my beers, and I guessed bolused everything. Attached is my Dexcom from the day. No correction needed.


I think that’s the biggest benefit with Fiasp for me. It allows you to regain some spontaneity. There is no longer a need to dose 20-40m mins before eating to avoid a post prandial high. I and others are getting the same kind of reaction, bolusing with food.

Why is this a big deal? Well you are bolusing for what you see, not what you might see and that reduces the risk of both lows and highs. You can even dose post eating (although I wouldn’t recommend it) and still reduce post-prandial highs.

In other words, while there may or may not be a significant clinical difference in Hba1C as a result of using Fiasp (and we’ll see that in the not too distant future with the results of the ONSET 3 or 4 trials), I’d say there’s a very clear lifestyle and quality of life benefit.

What is it? It’s that faster insulins make living with Type 1 easier, and in this context, Fiasp = greater Freedom.

To quote Peter Fonda in The Wild Angels:

We wanna be free.

We wanna be free to do what we wanna do.

And we wanna get loaded.

And we wanna have a good time.

That’s what we’re gonna do.



  1. Wow! That does look good. What puts me off is the lack of flexibility with my GP surgery; if I changed from NovoRapid to Fiasp and I was one of those for whom it didn’t work well, it would be another lengthy procedure changing back again!

  2. I totally agree with your piece, for me the main benefit is being able to spontaneously bolus when the food is in front of me, probably pretty much as I always used to before realising about the horrendous spikes this caused with Humalog Lispro. I eat out a lot so life is much easier. The insulin duration of action I’ve put at 2 1/2 hours having changed it from the 2 hours I put it at when starting. There is still a small tail to watch out for but have found this relatively insignificant.

    I am now going to continue with Fiasp in my pump, the first month I was undecided due to too many unrecognised lows and not dealing with meals containing too many carbs leading to highs later. My body now seems to have adapted to the new insulin and reacting well to it. The last time I ever experienced extreme hypos was changing from porcine insulin to Human and am wondering if there is a factor of adapapbilty to take into consideration?

  3. Are any of you just using a pump and CGM, as I am, or are you all using a Closed Loop system?

    • The people that have responded to the questionnaire are split roughly 50:50 pump and closed loop. All are using CGM. The experiences from those on forums and facebook varies across pumps and MDI.

  4. I guess I’m lucky – all these “amazing effects” others seem to get on Fiasp, I already get with Humalog. Pretty much never need to pre-bolus for anything, and typically I post-bolus a few minutes after eating.

  5. I just started using the OpenAPS Oref1 + Fiasp. I had been using Oref0 (and earlier versions) since 9/13/2015 with my normal rapid acting insulin with good outcomes. I can say that Oref1 + Fiasp is truly a game changer. WOW. I think Fiasp really plays nicely with the Oref1 algorithm. Excited to see my long term data on this combo.

  6. We switched from Humalog to Fiasp. After reading the publications about Fiasp I did not expect very much. However our experience has been a very positive one!

    It is now much easier to bolus for a carb-rich breakfast. If the starting BG is good, it is enough to bolus parts of the total insulin needed as we lay the table and the rest while we eat. The spikes are much lower, but also the drop later on is much softer. This causes much less temptation to overcorrect and we have had fewer hypos after bolusing for a large meal.

    On the negative side, the tail is notably longer than with Humalog. But since the drop is softer, it is very easy to handle. We now turn off basal completely for 2 hours after bolusing for a larger meal. I imagine the longer tail may become a challenge with many smaller meals throughout the day, but we have not tried that yet.

    We did not have to make significant changes to basals or carb ratios coming from Humalog.

  7. Am feeling a complete moron having posted weeks ago about my successful switch to Fiasp from Humalog Lispro that I’d been using for years on MDI then the last 5 on an Omnipod pump. Two weeks ago I examined the insulin carton closer and realised the pharmacy had been giving me NovoRapid with insulin aspart on it and their own label clearly labelled ‘ KNOWN AS FIASP’ . A serious dispensing error! I’m now in ‘discussions with the chemist about this and have been using the correct Fiasp insulin for almost 2 weeks.

    From this incredibly annoying error I have noted that for me, that the change from Lispro to NovoRapid was quite a big one, NovoRapid seemed to work quicker, had better 24 hour profiles and that the change to Fiasp has followed quite smoothly with no significant alterations needed.

    From this I would say that to anyone changing, check closely what you are given, both Novo Rapid and FIASP are followed by ‘insulin aspart’, the GP’s don’t use PIP codes under their prescribing systems apparently and pharmacies could make the same mistake as it seems, Boots did!

  8. Is anyone using the 670 g closed loop system with Fiasp? I use it with humalog and notice that even when I put it in temp mode 1 hour before exercise, that I still have a low. So, I am wondering if having a quicker rapid acting insulin will prevent such? Does anyone use fiasp in the 670 and notice better results with vigorous exercise?

    • I’m not using it in the 670G, although I do use it in a DIY loop. What I would mention is that even though the profile means that more is used earlier, it has a similar tail length to Novolog. I’ve found with resistance training that when you’re in the tail it has less of an effect than regular Novolog does, but I’d still recommend setting an exercise target a good hour ahead of vigorous exercise.

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