48 hours with Fiasp. What are my first thoughts on Faster insulin Aspart?

If you follow social media, you’ll be aware that Novo Nordisk’s Faster Insulin Aspart (brand name Fiasp) became available earlier this year, having passed its European marketing certification. According to the Novo bumph:

Fiasp® is a mealtime insulin with a fast-acting blood sugar lowering effect. Fiasp® is a solution for injection containing insulin aspart and is used to treat diabetes mellitus in adults. Diabetes is a disease where your body does not produce enough insulin to control the level of blood sugar. Treatment with Fiasp® helps to prevent complications from your diabetes.

Fiasp® should be injected up to 2 minutes before the start of the meal, with an option to inject up to 20 minutes after starting the meal.

This medicine has its maximum effect between 1 and 3 hours after the injection and the effect lasts for 3 to 5 hours.

This medicine should normally be used in combination with intermediate-acting or long-acting insulin preparations.

This medicine can also be used for continuous infusion in a pump system.

Taking this in context, what Novo are saying is that it is considerably quicker than Novorapid (also insulin Aspart), which states:

NovoRapid® is a modern insulin (insulin analogue) with a rapid–acting effect. Modern insulin products are improved versions of human insulin.

NovoRapid® is used to reduce the high blood sugar level in adults, adolescents and children aged 1 year and above with diabetes mellitus (diabetes). Diabetes is a disease where your body does not produce enough insulin to control the level of your blood sugar. Treatment with NovoRapid® helps to prevent complications from your diabetes.

NovoRapid® will start to lower your blood sugar 10–20 minutes after you inject it, a maximum effect occurs between 1 and 3 hours after the injection and the effect lasts for 3–5 hours. Due to this short action NovoRapid® should normally be taken in combination with intermediate–acting or long–acting insulin preparations. Moreover NovoRapid® can be used for continuous infusion in a pump system.

Both of these are taken from the Patient Information leaflet provided with the insulins, and suggest that Fiasp should be pretty rapid and alleviate post-prandial spikes.

I managed to get hold of some on Friday, and decided that it was only right to put it to the test.

Given that this is supposed to be effective with a much shorter pre-bolus than Novorapid, the first test to be undertaken was Fiasp v Krispy Kreme. 47g carbs taking on 4.7u of insulin.

And yes, I did get the date wrong. That vial was opened on the 24th, not the 25th. I was perhaps a little overexcited! Anyway, with a ten minute pre-bolus, the rather tasty Lotus Krispy Kreme was consumed and I monitored glucose levels afterwards. Starting at 7.1 mmol/l, it peaked at 9.3 mmol/l for about 15 minutes, before returning to 7.3 mmol/l within three hours:

This seems to be very much in line with the claims, and my previous experience with previous Krispy Kreme was that I needed at least 30 mins of pre-bolus with Novorapid in order to get similar results.

So far, so good. Following this I then ate another one (I know!!), this time with  twenty minute pre-bolus. The results were rather different, as my glucose levels barely rose, and I was hypo after about 90 minutes. I suspect that there was interaction between the two doses of Fiasp, but I certainly didn’t expect to go low like that. Further investigation is definitely needed.

Really, I shouldn’t have just jumped in with assumption, and instead should have done the sensible thing, testing ISF and DIA of the insulin, so today, I decided to do this. The results are shown below:

This suggests that the first thing I need to do is recheck my basals as I appeared to be dropping when I gave that 1u. It appears that there is then around 20-30 mins where very little happen, before the downward slope starts, which comes to a fairly abrupt end some 75 mins after the bolus. There is then a flat section, before I see a slight uptick in momentum, suggesting that the insulin is mostly done. I’m slightly dubious about these results, as they seem to indicate a very short life (and it is still apart after all) and  a fairly sharp kick in. I could understand the faster start, but the lifespan doesn’t appear reasonable. As a result, I’ll be testing this again.

So how is it living up to the marketing that Novo have provided. Well so far, it seems to be living up to it, in as much as the action I’ve seen does seem to get started fairly fast.

There are one or two questions for me though.

  1. Does the tail vary by dose size? I get the impression that the larger doses required for dealing with carby food really last longer than the one unit test did. Especially when the cross over into a second bolus for Krispy Kreme seemed to really go low. It was an unexpected stacking effect. One to watch I think.
  2. It doesn’t always have an instant effect on glucose when taken with food. I’ve tried the unannounced cake test with coincident bolus, and I can safely say that the jump that resulted immediately afterwards was rather higher than anticipated. It started to come down again a bit sooner, but simultaneous eating and dosing where large carbs are eaten doesn’t stop a post-prandial high.

There are still plenty of tests required to determine what this stuff is really like and transpose that into the looping algorithms. I need to undertake further tests on DIA for example, and if possible in larger doses. As more people are explicitly using it we’ll gain a better knowledge base of behaviour, which is a little sparse at the moment.

But the biggest question, by far, is is it truly Faster? Well my initial cautious response to that is, yes. It seems to be.

But how do you get hold of it? Well…..

To get hold of it, I tried speaking to my DSN, Consultant, GP, etc. No-one could prescribe FIAsp as they had to wait for it to arrive on the formulary. My consultant said that if I could get it, then she would be very interested in the results.
However, harking back to blog post I made, the UK listing of these things isn’t by brand name but by insulin name, and this may be branded FIAsp but it is still insulin aspart.

I went to see my friendly pharmacist with whom I’d already been discussing this and we worked our way through the PIP codes to find the one that was in her system. She agreed to put a note on my account saying that when they received a prescription to order insulin aspart, they would order the FIAsp PIP code.
I then spoke to my GP and got them to change from penfills to phials,explaining why I was doing so. They were happy to support it as long as my consultant was, and were happy for me to confirm that.
The prescription for Insulin Aspart vials was issued on Thursday night. It went to my pharmacy on Friday morning. They ordered it and it was in by 3pm. Job Done.

No-one had to do anything they couldn’t, but it took a bit of me linking things together and taking advantage of the way the system works.


  1. Interesting read, I’m a bit annoyed I forgot to mention this to my endo last week as I find novorapid frustratingly slow to kick in at times (I need to pre bolus by 45 mins or so for breakfast) and so would be keen to give it a go, if only to reduce the time I need to sit waiting to see the downward dip after a bolus to allow me to eat! I used apidra for a long time which I found faster than humalog but then for me randomly trying novorapid (i.e. I was stuck sans insulin and a friend loaned me a vial but only had novorapid!) I found that faster than apidra but always keen to see something faster as I try to practice sugar surfing methods!

  2. Interesting article .Surely results from Novo Nordisk is more reliable than an individuals trial over 48 hrs, although good on you for trying.
    Will this insulin be available in Australia in the near future or are we considered a too small a market?

    • Hi Jennifer, results from Novo Nordisk are generally averaged over a pool of users, and described as such.

      I’m trying it out personally, because I think faster insulins will work well in Hybrid Closed Loops, and it is worth documenting my experiences as I go through that. As I’m sure you’re aware, for a long time, the advice has been that it is possible to bolus immediately before eating with the existing fast acting insulins, and as more people have obtained CGMs, we’ve learned that that isn’t really the case. I’m sharing what I’ve learned because much of the information we receive is heavily filtered by HCPs who don’t live with the consequences of the meds that we take, and first hand experience is always helpful.

      If you prefer to stick with Novo information, I’m fine with that, but I hope you find my experiences useful!

      With regard to when it will be in Australia, I’m afraid I don’t know. I’d recommend going direct to Novo Australia and asking them.

  3. Sounds interesting! Keep up the information definitely what diabetes is about if you are educated enough on things then it can make life so much easier! Also what was the PIP code they used? Any idea maybe make it easier for people to get from pharmacys


  4. Hi Tim are you still as keen? Yes I realise faster is better, but any other info/or concerns. I have an endo appt. next week, and want to push for fiasp, but not sure how it will be received… Is it any more expensive? Do nice have recomendations? Thanks john

    • I’m still using it and whilst my sensitivities have changed, Faster is definitely better. Especially when looping. Price is the same as Novorapid, but NICE haven’t looked at it yet.

      From what I understand, some groups are looking at recommending it for all pump users.

      So yes, I’m still happy with it for looping.

  5. I’m using Fiasp, it costs more in Canada than Novorapid does, $10 more which isn’t a big deal but insurance doesn’t cover it so that makes it much more expensive. I find it does work faster than Novorapid but it’s not how you would think it works, i.e. just twice as fast. It seems to take awhile to get going then take full effect about 1.5 hours in and then it’s gone. Whereas with Novorapid I find it takes about 2 hours to come to full effect and then it goes away more gradually. Not a scientific analysis I realize but this is my impression. It’s not a dramatic improvement over Novorapid but it is better, I’m just going to use it to treat hypers, can’t really see the point to changing for mealtimes, given the extra cost. BTW a Krispy Kreme isn’t exactly the best choice for a test! I did it using glucose powder.

    • Hi Steve, it’s interesting that you see that behaviour. In the various groups that have been using it, many see effects occurring much more quickly than that (I certainly did), and while I know Krispy Kremes aren’t ideal, they do provide something that I’ve struggled to stop spiking with. In this case, the Fiasp seemed to achieve that.

      I’m also not sure about the view that “It’s just gone”. I’ve been running it in a closed loop, and initially I’d set up with a 2 hour DIA, but after spending some time with it, it’s clear that there is still a tail, and that 2 hours really doesn’t work too well for me.

      But we’re all different, and sharing all of our experiences is a good thing!

    • I’m sorry Gabriela, but I have to disagree with this. I think that the more insulin that you inject, the greater the drop when it acts but I’ve certainly not seen it get absorbed any faster when I inject more of it, or with Novorapid.

  6. Fiasp is not yet available in the US but I will be in Estonia for a couple of weeks and want to try it. Does anyone know if you need a prescription to buy it in Europe and about what it costs?

  7. Great read. I am the first person in the clinic that I go to to use Fiasp. Being a diabetic for 42 years I have seen lots of changes in insulin. I was really excited to try this. The first time I used it I started out at 14. I took three units. 1/2 hour later I was at 13.6. 1/2 later I was at 7.2. Another half hour later I was low at 3.4. Needless to say I do not go anywhere without my glucose tablets! But I am so glad that when I do have a “krispy cream” moment, I can take care of it more so now than having my readings up there for a couple hours.

  8. Hello there, fabulous real person review of Fiasp. I am located in Canada and think I would like to give it a try. I am using an insulin pump and currently taking homolog insulin. Does anyone have any experience knowing if my ratios would be the same (or close) if I switched over to Fiasp? Also I read through other reviews that some users have been getting large lumps under where their infusion sites were placed when using Fiasp. Anyone else notice this or at least any difference in the sites from using your previous insulins? Also admin what did you find the best DIA time for your pump was?

  9. Hi, I have the same question as Chris. I am on the pump and my endo mentioned that I may need to increase my basal rate when changing from NovoRapid to Fiasp. Pumpers, please share your experience regarding basal rate and carb ratio changes when using Fiasp.
    Thanks in advance and Happy New Year!

    • Most of us haven’t seen huge changes at the start. If you’ve read all my commentary you’ll see that my overall requirements increased the longer I used it for, and it eventually became quite unpredictable. On the immediate changeover though, there was little difference.

      The most important thing to do is ensure you monitor carefully.

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