FIASP for Insulin Pumps


I haven’t tried it but I’ll give it a shot (pun intended) if it happens again (hopefully not!). Usually when my BG gets that high I reach for Afrezza right away, but I wanted to see if the Fiasp was going to work. Maybe it would have if I tried the extended bolus!



Especially for high carb meals, I will give a large bolus and a good extended bolus. And with fiasp, I have some REALLY nice numbers!
No matter what I did before fiasp for pre-bolusing, I never got this smooth of BG curves.


@Hammer - Wait until you get the G6. [Hopefully soon.] The combination of the Fiasp and the Basal-IQ is really awesome.

@Hammer - What do you have your Insulation Duration set to? We were at 4-1/2 hrs but have dropped it down to 2-3/4 hrs now on Fiasp.


@Tim35 I have that feeling that it work work great for me as well!
And I have mine at 3.5 hours right now. I tried it at 3 hours, but seems to be catching the tail giving me some lows.
I think with the Basal-IQ I will shorten the time to 3 hours again, and let it stop the tails.
I kind of figure that using Basal-IQ will let me do a super bolus and not worry about setting a temp basal rate.
I also think I should soon have a FLAT nighttime BG curve!


We (now) have a gentle downward slope on the cgm and the Basal-IQ catches it and flatlines it almost exactly at 80.

The tail on the Fiasp seems quite short for us. I have been considering bringing it back further to 2-1/2 hrs.

Which just means we make more use of extended bolus then we did previous while on Humalog / Novolog. As well, we do not wait for 3 or 4 hours after eating to make additional bolus corrections but rather about 1-1/2 hrs after eating (depends on food obviously) if the BG looks a little higher than expected we will hit it with another unit or so.

Between the Fiasp and the Basal-IQ this is really letting us do much more fine tuning then we were able to do previously. The update is totally blowing me away. This is way more then I expected.

Plus to have the algorithm being so incredibly simple that anybody can understand how it operates. That is just awesome. I am a nuts-n-bolts guy. I like to know how the guts of things operate.

Tandem has a good page that completely explains this (you just have to scroll down on the page which at least for me was not immediately obvious)

How does Basal-IQ Technology work?

Basal-IQ Technology uses a simple linear regression algorithm that predicts glucose levels 30 minutes ahead based on 3 of the last 4 last consecutive CGM readings. If the glucose level is predicted to be less than 80 mg/dL, or if a CGM reading falls below 70 mg/dL, insulin delivery is suspended. Insulin delivery resumes as soon as sensor glucose values begin to rise. Insulin may be suspended for a minimum of 5 minutes and a maximum of 2 hours within a 2.5-hour rolling window.

That is it. The entire workings of the algorithm.


I just gave Apidra and Fiasp a try over the past few days.

I LOVE Apidra! Bolus started acting in 25 minutes and a smooth 2hrs and 45 minutes of IOB. Dropped my insulin use by 61% from Humalog.

Fiasp doesn’t agree with me at all. Too slow - pretty much the same as Humalog, so no benefit of changing. And it gave me a weird mood change on the downward slope. Just felt horrible. Everyone has different reactions. Humalog worked for me for 17 years, but just flat quit working about a year ago. Way too slow to act, and I now need over double what I needed two years ago.

Unfortunately my t:slim flat doesn’t work with Apidra. 22 hours is the longest I could go without total occlusion requiring a cartridge swap out.

As a result, I will be switching from the t:slim to the Medtronic 670 ASAP. It also helps my decision given that I absolutely hate Tandem’s screaming beeps, buzzes and endless Lawyer warnings. I call my t:slim “The screaming little (illegitimate offspring.)”

My wife works for Dexcom and I use their CGM. I don’t see a massive need for integration for me, so this shouldn’t be a showstopper.


The 670g system is also a ‘screaming little b’ but tolerable


My in jest response wouldn’t be tolerated these days, one or two would have no idea that I’m joking.

But thank you for that information!


That was my experience too, but I personally have no interest in changing to Medtronic…not that I could afford it.

That is also an annoyance, but perhaps the most annoying thing to me is that you can’t silence alarms without pulling it out and unlocking it. So for the CGM part of it, if an alarm is going off and you can’t pull it out at the time, such as while driving, you get to listen to it go off either continuously (for urgent lows I have it set to repeat continuously, but when on a new sensor it often thinks I am urgent low when i am perfectly fine), or at least as often as the repeat interval is set.


Hello, thanks so much on your thoughts with the insulin fiasp. I’ve been using it for only 24 hours in my medtronic 640g. I eat pretty low carb. For the moment all is chaos.
On the French forum they have told me to hang in there for at least 2 weeks to have results. No one here has spoken of problems in the beginning. I have been giving lots of corrections which act like water. (as some of you mentioned) For my usual breakfast I used 0.8u Humolog insulin 15 minutes before hand. With Fiasp I injected 3 units. I jumped up to 200 an hour after the meal and then slowly road it down to 143 before lunch.
Another thing that was mentioned in the French forum was that several people upped their basals 30%! Did any of you do this?
For lunch I started at 143 and injected the 2.5 units I would normally need. I have since then 2 hours later injected an additional 3 units plus doubled my basal and I am at 170.

I hardly know where to start! For me the fiasp should be called fiasco! I appreciate any advice you can give. I am sure 24 hours is hardly enough. Please tell me what you think???



For us, the Fiasp is wonderful. However I have heard other people state that they saw little to no improvement with the Fiasp. There definitely seems to be a substantial difference from person to person.

Have you tried a syringe injection of the Fiasp to see if it works as you would hope from a syringe? My suggestion would be to try this half a dozen times. This removes everything pump related from the picture. From a syringe, if you either see no improvement or if it is actually worse than your previous Humalog insulin then this may be faster to get to the decision where this simply is not a good choice for you. On the other hand if the syringe works really great and shows improvement over the previous insulin then you may be able to focus more on the pump or infusion site or something along those lines.


Thanks, such a good idea! I keep pouring the insulin in and think I’m going to get low! And nothing!
I’m going to try that. I see that you use the extended bolus too which I do with humalog but haven’t since I have no result with the FIASP
i must say waiting 2 weeks withsuch high numbers just to see if it works, isn’t so great!
Thanks again. I’ll let you know how it goes. Might be help for someone else.


I agree with @Tim35 on trying an injection to test the results of Fiasp separate from using it with the pump.

For me, I am still a happy customer! 7 months in and everything is still working great for me.
I found that I can RARELY hit 4 days on Fiasp. It loses it’s mojo at 3 to 3.5 days. If it wasn’t such a pain to get the timing down, I would change my sets out at 2.5 days. But 3 days still works good for me.

Now to get my Dexcom G6 in so I can try out the low prediction and set it to be AGGRESSIVE at night! I like the idea of Fiasp with the Basal-IQ because I think it would have better control with it’s shorter reaction time and shorter tail.


Our prescription is written for a site change at 2-1/2 days. We typically change at 3 days. I don’t fill the insulin cartridge completely so as to decrease the temptation to try and stretch to 4 days. The long term risks do not seem worth it. So we have not actually seen if the Fiasp benefit falls off drastically in the 4th day. But we have seen no [obvious] drop-off during the 3rd day.

We did bump our overnight basal up 15% for night as well as moving some timings around based on the Dexcom Clarity graphs. There is obviously a limit for what the Basal-IQ can handle. If the number and width of the Basal-IQ “red lines” gets too large then I would reduce the basal by 5% at a time and see how the change works over a number of days/nights. I think we currently have a good basal rate in conjunction with the Basal-IQ. We normally get the Basal-IQ kicking in overnight but it does not seem excessive. We typically are waking up straight and level at 80. It really is unreal.

And if the Basal-IQ is not able to handle a particular low then there is of course the URGENT LOW alarm from the pump and smartphone. I think we have had two URGENT LOW overnight in the past four weeks since using Basal-IQ (with Fiasp)? For us that is a HUGE improvement.

Agreed. I think the combo works really great for us and this absolutely is what we are seeing. The shorter tail on the Fiasp does mean we have to use more extend on bolus for various types of foods but that is not a big deal for us.


Wow! As a parent of a child with diabetes, you will eventually graduate from this day to day care. I hope that your child integrates some of what you’ve learned together into his care when he takes over the reins. Congrats on your success.


@Tim35 This is SO GREAT to hear!


As you are low carb, does this mean you eat a lot of protein and fat?
If this is the case perhaps due to the different profile of Fiasp you need to consider how you bolus for your meals.


Yes you’re right about that Sue. I’m not strict low carb but the extended bolus is a good idea. Things are much better. I’m still doing syringes for meals with correction and basal in the pump. Last night I was a little low but I don’t mind. Insulin seems to start working - no more awful highs ! This morning woke up at 76!. And I’m seeing what I was hoping to see.
I hope this will continue today and I can start making small corrections for basal etc.
I sure wish I had a dexcom but am doing with the FreeStyle Libre (reimboursed by French health system). Thank you so much all of you for your help. If you have any more tips, don’t hesitate. I’m open and admire the people here who have such good results! And are so kind in answering! i’ll keep you posted on future events.


You are more than welcome :slight_smile: It might be worth your while doing a basal test, I know I found I had to reset my basal when I went on to Fiasp.


If you don’t mind the question, did your basal rate reset for Fiasp deliver more or less insulin? Did all basal rates go up (or down) or was it some up and some down?