Fiasp - not w pump - poor results

I use Tresiba and had been using novalog/homolog until last month when I switched to Fiasp. I was very excited because I assumed better control of my glucose. It has absolutely not been the case. My Dex is going off for high glucose all the time - I know I could shut that off or raise the level - and I’m using about twice the amount of insulin for ineffective control. My endo has been away and will be this week. I’m going to switch back to my old insulin.
So - I guess it’s moot since my estimated a1c is now nearly 1.5 points higher w Fiasp and I don’t see how to “fix” that, but have any of you (non-pump if it makes a difference) had a really disappointing experience with Fiasp.
Thank you for sharing your experience.

I calculate my dose based on the number of carbs I’m about to eat. I use the glucose readings from my Dex. The a1c I referred to was an estimate for the last three weeks of readings - the time I’ve been using Fiasp.

I don’t find Fiasp is as effective and wonder if others are having a similar experience - non pump.

Do you eat immediately after dosing, or wait a bit?
I use novolog in pump, and like to wait until I see dexcom starting to go down.

Was the fiasp a sample from doctor, that may be old or not stored correctly?

I’ve tried more than one batch. Thank you.

Thank you.

When are you experiencing the highs? When I used Fiasp (in a pump), I found my Dex often showed a double camel hump: I’d rise a little bit after eating, start going down, then get a second, often higher rise several hours after eating. I’d expect to see that with high-fat/high-protein meals, but these were normal meals.

I fiddled around with doing two or three boluses during and after a meal, and various lengths and sizes of extended boluses. Some people have found a shot of R works for the second rise after certain kinds of meals, but I never tried it. But given that I wasn’t impressed with Fiasp for other reasons – I didn’t find it significantly faster than Humalog, and it irritated my pump sites – I simply went back to Humalog.

I’m heading the same way for the same reasons.

@beacher’s comment is along the lines of what I was going to say. I’ve also experienced the “double hump” effect pumping Fiasp. One thing is that it has a shorter “tail” as well as shorter onset, and this seems to be more pronounced for some than for others. A big difference between injections and pumping is that pumps allow you to program a “dual bolus” which helps account for high fat meals and I find it helps account for the Fiasp tail as well, when you need it. So a supplementary injection might help, or it may just not be a good insulin for you. In my case I find it much better at getting into my system fast enough to rein in post-p spikes and I especially like that it seems to clear more completely, which makes temp basals much more effective prior to exercise, a big issue for me. But I realize thats a pump thing, and as always YDMV.

Thank you

Fiasp has only been recently approved in Australia and I have only been using it for just over six weeks but I am also having troubles adjusting to it.

I can’t use a pump and I am using Ryzodeg 70% Degludec (rys) and 30% Aspart (rys) with about a 30 am 70 pm split for over a year now. Ryzodeg has worked well for me but Fiasp is not working as fast as it should.

I also have to also have be aware that I have already have fast acting insulin with my morning injection if my BGL is low. If Ryzodeg was available in the long acting Basal insulin, Degludec I may have less problems.

I knew how to adjust or make corrections with NovoRapid but I have also had two bouts with the flu during the last six weeks and I have had trouble keeping my BGL from going high.

I am only on to my forth pen of Fiasp and will keep trying to get things right for awhile yet.

So Ryzodeg is approved in Australia but not Tresiba? Why not switch to Lantus or Levemir then? I’m not sure what the benefit would be of using Ryzodeg since you are forcing yourself to take a dose of NovoRapid, whether you need it or not, every time you take your basal. I can’t see how any benefit Tresiba has would outweigh having to do this, but we’re all different.

Based on Novo’s information, the onset is faster, but length of the tail is the same as Novolog. But the concentration on the tail looks slightly lower. That makes sense because the Fiasp additives only helps Insulin Aspart (Novolog) enter the blood stream faster. But once there, it should behave much like Novolog.

As @DrBB pointed out, Fiasp seems to behave differently for different people, but I think it’s important not to assume Fiasp has a shorter duration. Until someone sees how it behaves for them, they should be just as wary about Fiasp hanging around as they would be with Novolog or Humalog.

Yes, I’ve seen the chart before, but all I can say is, that’s not how it behaves in situ at least in my experience. One of the most distinct differences is that i can do a temp basal an hour before exercising and totally rely on it, whereas with Novolog I had to zero it out 2 hrs ahead and I’d still half the time end up going uncomfortably low. My endo has also seen this—she was the one who recommended that I shorten up my AIT setting by an hour. Of course I totally agree that this is something you have to experiment with, but for me the difference is quite dramatic. I did get a single-vial prescription as a try-out when I first started on it, which I’d recommend as well if your Dr is amenable to that.

I did ask my doctor if Ryzodeg was available without the Fast Acting
Insulin and the answer was “No”.
Lantus didn’t work for me and Ryzodeg has been better than Levemir.
Another problem that I am having since I have had since having the Flu
and changing to Fiasp for corrections is, THERE ARE LARGE differences
occurring between the 3 difference METERS that I use to cross check to
see if every thing is stable before I inject. Even at normal BGL I
have been seeing over 20% differences between meter readings.
I use the Accu-Chek Performa, Contour Next and FreeStyle Libre for cross checks.
At this stage I am blaming the flu but after I have used Fiasp these
differences could be attributed to the faster acting Fiasp.
I know that meter readings are not that accurate but all good brands
will give similar readings if your blood is stable eg no recent
exercise,food, stress,hormones or insulin.

I factor Novolog for 5 hours, and Fiasp for 3.5 hours.
That chart is just that, a chart.

And I would bet money it was created for at least two reasons.

One, it covers their butt to keep people from stacking insulin.

Two, it most likely does have a longer tail for some people, and thus the average tail would show, averaged over what sample size?, a longer tail.

From what ‘most’ people here have reported, 3 to 4 hours.
But, do what most of us did, start with 5 hours, and work your way down to what it actually is for YOU.



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I thought FIASP was wonderful when I started using it a couple of months ago. It made not going over 140 very doable. I loved it along with Novolog and Tresiba, but I eventually had to use more and more of it to get the same results. Eventually it didn’t work nearly as well as Novolog.

I have stopped using it and am only using Tresiba and Novolog and I am much happier. I was using FIASP three times a day, so maybe I was using it too often? Now I will only try it again after a few weeks and see what happens.

I use it way more than that, but mostly because I’m not particular with my diet and treat my pen like a pump. It definitely is not as effective the longer you use it, and I find it is more effective when taken in smaller amounts (eating less/lower carb, which somewhat defeats the purpose of it), but still find it way faster than Novolog. I might need to use much more of it, I’m not sure, but I gave up on carb ratios long ago and just dose (i.e. stab myself a million times) according to my CGM.

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This is an interesting discussion, and very timely for me. I recently started noticing that my t:slim cartridge filled with FIASP would stop being particularly effective in the last 50-90 units. My first theory was that my new t:slim (just got in Nov ‘19) didn’t deliver consistently in the last part of a cartridge. But I checked my records from my previous pump (t:flex) since I started using FIASP and saw identical results. Plus occlusions 100% of the time after ~48 hours when I filled the 480U cartridge all the way, which had caused me to only fill with 300U. I didn’t have any of these problems with Novolog.

I checked with our local Tandem trainer, who told me that she had heard frequent complaints about losing BG control with FIASP after 48 hours. So I went back to my data sheets and sure enough, passage of 48 hours was most highly correlated with loss of control.

So just for fun I asked my endo for a sample of Humalog (haven’t used that for maybe 12-14 years). Three fills in the pump to use it up. Then used FIASP for a vial, then Novolog for a vial. Results - these apply to me only, and probably only for an instant until my body decides to change its mind - Humalog showed good control, acceptable time to work (had to change my FIASP habit of bolusing at the end of a meal to being at the start of the meal); Novolog was similar to Humalog but started losing effectiveness toward the end of a cartridge, but not as strongly as FIASP. And FIASP continued to be ineffective after a couple days.

My conclusion is that since I’ve been using Novolog/FIASP only for maybe 12 years, my body has gotten resistant to it. So I’m going to change to Humalog for a while. I’ve still got 12 vials of FIASP in my fridge so I’ll probably go two Humalog vials then one FIASP until my inventory runs out. Then I’ll run my stats again to see what happens.

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