FIASP for Insulin Pumps


Yes, I have active insulin set to 2.5 hours and it works very well. Remember that the FIASP leaflet, at least in the US, is geared to MDI and not pumps with CGM. As with all things T1, experiences will vary.

I forgot to mention that CGM is benefiting from FIASP. With fewer hypo/hyper excursion, sensor calibration is easier and works better.


It peaks much faster than Novolog and once the peak is over there isn’t much left, even if it slowly tails off in the same amount of hours as Novolog. I find it is the same on pump or MDI. While this can be a good thing to prevent lows, it can be annoying when food keeps digesting after the peak is over and I find this is the case for most things I eat.


One of the trickier things with Fiasp is high-fat meals where delayed digestion is a factor. I’ve seen a number of people suggest that you do a delayed bolus for that, but I’ve been confused about exactly how or whether to combine that with pre-bolusing. Even with the fat, I’ll get some effect from the carbs early on, and if I don’t get my BG down ahead of time it’s really hard for a later dose to catch up. I basically see two peaks, an initial bounce that if I do things right usually levels off at 130-150, then another later one that will go up over 200 if I don’t get ahead of it. So once I see that initial one top out, I take another bolus for the anticipated second one. I suppose I could just program a dual wave, but that seems to diffuse the effect too widely.

What @Scott_Eric says about this matches what I’m experiencing. One of my hardest challenges is that my biggest carb intake tends to be at the midday meal, but I bike commute and I really need to have minimal IOB by the time I’m riding home or I’ll go super low. I’ve been experimenting with setting a temp basal of essentially zero a couple hours ahead of departure, but with Novolog it never seems to work. I basically have to just tolerate a big post-prandial spike so I still have a high enough BG to get home on without plummeting into the 60s or worse. “Don’t correct too much or you’re going to crash on your bike ride!”—which is kind of absurd. Since switching to Fiasp the temp-basal thing is working MUCH more effectively–whatever the graph shows, the effect is that it clears more rapidly.

OT, but it was exactly this quandary that I was hoping 670G auto-mode would iron out for me. I hate having to do all this head-scratching, tea leaf-reading to predict what I have to do now to account for what’s going to happen 3 hours from now and then what if it rains and I can’t ride, or if I think it’s going to rain and then it doesn’t so I could ride except I have IOB and blah blah blah. Gimme a smart pump that can figure all this out for me! I thought. Unfortunately the darn thing did a worse job than I could do manually, while locking me out of the controls that would let me adjust things on my own except by dropping out of auto entirely. Which kinda defeats the whole purpose. /digression


@DrBB, have you considered getting your Fiasp from Canada? A vial will probably cost $30-40. If this cost is same or less than copay, that’s the way to go.


I’m getting nine vials (90 days’ supply) for $80 (same copay as for 30 days), so I don’t think that would save me anything. This time around they counted the first three as a “partial,” so I only paid the $80 when the rest came in. But it’s a good tip to have out there for others who encounter this thread.


I really haven’t figured out high fat with carbs (for me nuts and peanut butter). I’ve been tinkering with programming a square bolus. Then I look again later and adjust - cancel square and bolus the balance if high, cancel square if low or continue if it looks good. I’ve also been experimenting with under counting the carbs a little, e.g. 2.5 or 3 per oz instead of 4, simulating that some of the carbs get lost into background.

As to exercise or other physical activity, I’ll eat a small snack. Just started 670G and plan to try auto mode later.


It’s been a while since I chimed in on my Fiasp results with my Tandem t:Slim X2. I am still having amazing results with Fiasp after 2 months of usage vs my previous experience with either Novolog or Humalog.

There is a downside, however. As others have mentioned the site effectiveness drops off dramatically after 2 days. I definitely can’t stretch it to a full 3 days as I have always done with Humalog, and previously Novolog. I tried changing the site after 2 1/2 days and still have issues toward the end. For me, the maximum time I can use an infusion site is 2 days. After 2 days, the effectiveness drops off dramatically and even sometimes seems to disappear. I have had a couple of situations happen on the 3rd day where my BG got in the low 200s and I would keep bolusing to drop it down but it would never come down. I had to finally resort to giving myself an injection and within a short amount of time my BG would drop back to normal. I would then change the infusion set.

Based on this site effectiveness issue, I have decided that trying to stretch the infusion sets beyond 2 days just isn’t worth it. Even with this negative, I’m sticking with Fiasp as the benefits for me are worth the extra infusion sets. It does an amazing job of greatly reducing my spikes without having to prebolus as I was having to do with Humalog.


I have had some sights fail on the 3rd morning. And others work into the 4th day.
If they fail, they pretty much FAIL. I don’t get much of the downward slope of effectiveness.


Haha that is my experience with Humalog already, so if it at least stays the same I would be fine with that!


My experience is the same during the summer months or warm weather. Winter 3 days was fine summer months and 2 days is the absolute limit which must put a huge strain on peoples finances if they are having to pay out of pocket for their supplies.


Same problem with site duration and I was considering trying that. Some people fill their reservoirs right up so they only have to change sites a couple of times until the reservoir is empty, so I was thinking that if it’s just the site… But I was told back at the start of pumping that, whereas insulin stays good indefinitely in the glass vial, there’s something about the plastic reservoir that causes it to degrade. So maybe Fiasp is more sensitive to that effect.

ETA: for me the limit seems to be about 2.5 days. I get my infusion sets on a 3-month/one-copay basis, and I already cut it pretty close sometimes if I’ve had more than a couple of pullouts or bad insertions. Kinda worried about this quicker pace. Not to mention using up the real estate much faster.


I have been using FIASP in my omnipod since April 2017. So for the 1 year summary… still loving it. I mentioned a while back in this thread how I changed my settings.

I get 3 days no problems out of my pods.

Lately, I have been prebolusing less for high carb meals as I have found it absorbing faster but I still usually do 15 minutes early for meals that are lower carb. I find a large dose absorbs very fast but smaller doses take longer to get going.


I find the same. If I do a 0.25 or 0.5 unit correction to turn around an upward trend, it seems to work almost instantly. But if I bolus more units when I’m closer to my high limit (but not yet high), the trend can flatten out pretty quickly but may take half an hour to start turning around.


I was given a sample vial of FIASP and used in my 670G (in auto mode) and after using it 6 days I saw my target range go from 78%-90% and had 2 lows and only 1 instance above 250. My endo wrote me a RX for FIASP last week and I’m pretty excited about this new drug!


My endo still seems skeptical of it and wasn’t super interested in pursuing it. I am hoping that as time passes he will be more open to it.


Has anyone tried a hybrid approach, using Fiasp via a pen or injection and Novolog/Humalog in the pump just for basal rates? Apart from the Rx complexity of working with insurer pharmacy benefit managers who are mostly ignorant of T1D, this approach seems like it might avoid the site irritation issues most commonly mentioned with pump use of Fiasp.

Personally, I am very intrigued by the quicker peak AND the shorter duration of Fiasp. In my own use and with a BMI about 20, Novolog lasts up to 8 hours and Humalog about 6 hours. A shorter duration would be a lot easier to manage.


What about just buying Novolin R over the counter for pump basal? It would require more lead time for temp basals, but would avoid the insurance complexity.


At that point it would make better sense to use Tresiba.
Unless you really need drastically different basal’s throughout the day.


Sorry, MDI for Tresiba. No insulin pump at all.


My Flexible Spending Account paid me back for the 3 vials of FIASP I bought in Canada ($31 US per vial) without an Rx. I submitted under insulin, and other diabetes supplies. Any other meds, Rx or OTC, they want a label or receipt with the patient’s name and showing there is an Rx.