Using Fiasp

My son is still on his baseball 50% of basal from Lantus so he doesn’t have to wake up when he doesn’t plan it well. He can just unplug, shove the pump under some pillows and get back to sleeping.


I do not know if this is relevant for the difference you saw from initial use and later use, but perhaps this might be good to investigate and ask about. Good endo questions for sure.

There is some research that vitamin B3 can lead to insulin resistance. Since Fiasp uses B3 as one of its excipients, do you think this could be a factor in the changes you saw?

What do you think? Could this be a factor?

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We are very happy with how Fiasp works for us.

My intention was to provide information on Fiasp as we have directly observed while also taking into account what I have heard from other first-hand reports.

Past that other items quickly move higher on my list of priorities.


It seems to me that Fiasp either works really well for people (e.g., very noticeable speed difference) or doesn’t work at all (e.g., no noticeable difference from other insulin). I’m in the former group.

I’ve been using Fiasp for three years, and it is dramatically faster than any other insulin I’ve used (I’ve used Humalog, Apidra, and NovoRapid). I used to have to pre-bolus by 45 minutes to not spike after a meal. With Fiasp, I don’t have to pre-bolus at all. I used to have to wait an hour or more after a correction to see any movement in my blood sugar. Now, I often start to see movement after 15 minutes.

Apparently the decrease in effectiveness is a fairly common phenomenon. I haven’t experienced this, but I also haven’t put any effort into recording the timing of things. I just know that it’s a very noticeable difference and I would not go back to another insulin.


I agree, but what’s interesting about it is, unlike NovoRapid/log, there are times when it has to be taken 15-20 minutes after eating because of how fast it can work, depending on what you are eating and the trillion other variables that go into dosing decisions.

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@Eric, thanks so much for this review from IDS and Gary Scheiner. It is very very helpful! I met Gary at a diabetes conference in 2013, He is very knowledgeable on all things diabetes. I attended two of his sessions that year, they were great! He lectures at several conferences each year.


Hi @Richard157!
Yes, I have heard a lot of positive things about Gary Scheiner and IDS. I have never worked with him directly, but I really like his BG meter reviews!

If I am not mistaken, @T1Allison has also worked with IDS. Is that right?

I hope nobody thinks I am bashing Fiasp. Not at all. I am sure it can be a very helpful change for some people, and certainly worth trying. I think people should always try new things like that to see what works best for them!

There was one year when I tried/used 9 different insulins. :man_facepalming:

So I definitely believe in experimenting with new insulins. I would always encourage people to try it out.

The only caution I have is that people should set proper expectations. I saw issues with Apidra when it first came out and people had some unrealistic expectations with that one.

This is unrelated to the topic, but as a side-note…

You are legend. :star_struck: The number of years with D and things you have seen in your journey…

Time for a new endo? The audacity for them to say “No” to you, of all people.

They should be bowing before you and letting you write the scripts. Just my opinion. :wink:


Yup. Gary is awesome. He and his staff are the absolute nicest people. I did my initial pump set up with Gary and a later tune up with him. I’ve also worked with Jenny. She’s great.


@Eric, I have not utilized Gary Scheiner’s services, so I don’t know the members of his staff. I see that T1 Allison has answered your question.

LOL, your referring to me as a legend is so funny. I humbly reply that I am just another T1D, with a longer duration, but still needing help from my endo. She has been very good at working with my insurance, and getting things covered. Aetna was very stubborn, until my endo did her thing.
My endo is the only reputable one in my area. I don’t want to drive an hour from home, and perhaps have no better luck.


That’s only weird in the mind of trainers, CDEs and endos. Probably because they don’t have to live with diabetes themselves. In the past my CDE has also suggested that I should change everything at the same time, but I’m not going to do that. I change the cartridges when I’m out of insulin and I will continue doing that. Actually, quite frequently I don’t change the cartridge till my pump indicates --.- units left and in some cases my pump literally runs out of insulin, because even the ‘reserve volume’ below zero has been used, and the pump will stop delivery and warn that there is no insulin left at all. I just don’t like the hassle of filling reservoirs and priming the tubing.


I second this, @Richard157 ! :smiley:

I have also worked with IDS. When I was first diagnosed in 2002, my family and I saw Gary periodically. (His office is actually really close to where I grew up!) He taught us so much about navigating the ropes of diabetes. I reconnected with him in 2017/2018, which was really strange yet fun! He got me set up with Jenny, who I worked with for a bit to relearn how different foods and their components (carbs, fats, protein) can affect bgs. They’re an awesome group and are willing to meet people where they are to achieve whatever personal goals that they have.


Sure, it could be! But like you phrased it, it could be a factor in the changes I’ve seen. As in, if there is a trend of slower responses to Fiasp over time, I think that it is certainly a multifactoral effect.

Notably I will say, I similarly saw slower responses from Novolog over years. And Novolog doesn’t have B3, which leads me to think that it’s more complex than B3 alone. (but of course over my years with novolog I had lots of stuff going on, like growing up!)

Additionally I will say that I doubt the B3 component of Fiasp clinically significantly contributes to insulin resistance (in me!) based off of my data, TDD using Novolog vs. Fiasp). But I do acknowledge this is a sample size of 1 and that there could be confounders to the previous statement :woman_shrugging:

I personally don’t believe these Fiasp response changes to be that significant to focus time (that I don’t have much of right now) on, but I have noticed them. Maybe something to look into over the summer.


I am with you 100% on all of your points!

Yes, only possibly a factor, and if it is a factor, only one factor of many.

And other factors that affect the speed could also be seen by you and others with other types of insulin too.

Agreed, the B3 thing may not even be a factor at all! I was simply posting that as a point of discussion because of the studies involving that. It was very interesting to me.

We know how interconnected everything is in the human body. Like you mentioned the other day, about vitamin C and iron absorption. Crazy how much everything affects everything else!

So many things that a lot of people don’t know about. As an example - milk interferes with the absorption of thyroid medicine. Do all diabetics know that? If you take your thyroid meds in the morning and then have a bowl of cereal… :frowning_face:

So I just raise it as an interesting idea to look at and consider - that everything added to the body can in some way affect some other thing.

Anyway, just wanted to raise is as a discussion point. Certainly not as a statement of fact, or even as a hypothesis. (I’ll leave that to the future Doctor L to do one day in the near future… :grinning:)


And please continue to do so! It is interesting! I don’t want to be complacent on learning new stuff so even if I may seem resistant, I’m not at all. Good stuff and nice sources :+1:


Kind of a tangent - how commonly known do you think the thyroid medicine and milk thing is?

Doc specifically told us that when we started on the thyroid meds. Something about grapefruit also but that is not typical for us so that faded into the background fast.

I have other relatives on thyroid meds and they are aware so I think this is likely to be a common point of discussion. Especially as the decision to go on thyroid meds and the dose to use is not a quick 5 second discussion with the Doc. It usually is a rather long conversation over a number of appointments coupled with multiple labs both before and after starting. There should also be at least an annual lab for the thyroid and discussion with the Doc if the dose is still appropriate.

Time of day can also be an impact. Which does not necessarily mean that morning or night is better but it likely does mean that consistently taking the thyroid med at a similar time of the day is a good idea.

  • Rapid acting insulins are particularly slow for me
  • Fiasp was significantly faster than Novo but still gives me enough of a tail for a lot of meals
  • There’s no reason you can’t take a follow-up injection e.g. hours after eating to cover that period
  • But instead of that I sometimes combine Fiasp and Novo for slow-digesting meals
  • The school of hard knocks has taught me “until you’ve tried everything, you don’t know whether something better is out there.” There are four medications I couldn’t live without that I had to push hard for.
  • I also tried intramuscular injections without medical approval. Now I use both Fiasp and NovoRapid intramuscularly (in muscle) for most meals, to avoid highs within the first 2 hours or so. IM Fiasp is the fastest.

With regards to Fiasp “getting slower”, I find all my rapid-acting insulins slow down over time. When I rotate them I can sort of “reset” them. (There are things called anti-insulin antibodies which deactive insulin for a few hours which slows down its release, and I have elevated levels of these.)


How long does a reset take for you?


This is only something I have been exploring recently. What it looks like right now is that if I quit an insulin, it has a reasonably fast profile when I try it say a month later.


Here is a reference for the anti-insulin antibody testing, from Penn State Hershey.


(Totally unrelated, but Penn State Hershey was the first site referenced from Google, and I used to be pretty good friends with a guy from Penn State. But we kinda lost touch, not sure what happened. Seeing the PSU reference reminded me of my old friend.)