Adventures with Fiasp –  there’s plenty to learn.

Adventures with Fiasp –  there’s plenty to learn.
Adventures with Fiasp –  there’s plenty to learn.

Following the variation in absorption I felt I was seeing in my last post I’ve since had a bit of a reason to pause for thought. I was adamant that it couldn’t be the site where my cannula was, as I’d had no issues with Novorapid absorbing there. I rotate around my midriff such that a site gets re-used roughly every sixty days. Since I’ve been pumping, that would be about six times. I figured that shouldn’t be enough for damage. And yet…

The last week or so has been spent in an area on my lower back. If you think of my spine as 12, then the four sets I’d used have been placed roughly between 10 & 2. All of them have given me absorption problems in some shape or other, but in this time period, only using Fiasp. To be honest, it was a little stressful. I couldn’t see what was wrong and started to hypothesise. As my last post showed.

Then, a few days ago, after another couple of days of silliness, with hard to manage levels, I shorted the old set and put another new one in. At roughly 2 on the clock I mentioned earlier. And it’s worked marvellously. To the extent that with eating fast carbs last night and using a normal Fiasp IC ratio, I ended up where I wanted to (Easter eggs are bad….).

So what can I read into this?

Well the thing that’s most notable about the new site compared to those between 10-2 that I previously mentioned, is that there is a greater amount of subcutaneous fat than in those areas. Now I’m not a fat bloke, but small love handles sometimes can’t be helped.

So on me, does the amount of SC fat locally to the cannula affect absorption? It looks that way, but I put my hands up to not fully understanding how the added B3 in Fiasp makes it absorb more quickly, and perhaps that’s key to difference. However, as we approached 3 days on the same cannula as the above picture, with a similar meal carb load, this was the result I got.

Even timing is similar and yet I’ve seen two rather different reactions.

So what am I taking away from this?

So far, I’m not getting consistent, outcomes from this insulin on sites I thought were good. When it works, it’s  brilliant but it’s much tougher when it won’t. That can make managing life much more challenging. Discussions with various people on social media suggests that some people have reduced their set change to once every two days as a result of loss of absorption using Fiasp. It’s not abundantly clear what’s going on, so there does seem to be a requirement to do some more testing. I’ve removed the risk of the insulin in the reservoir denaturing by reverting to 3 days use of reservoir and tube, so this leads to a suspicion of sites.

Given this hypothesis, I feel that an experiment is in order to determine whether there really is variation across the three days of site use, so in my usual n=1 fashion, after my next set change, I intend to do a fasted ISF test on the mornings of the three following days and see if I see any difference in the outcomes. It may yet prove to be inconclusive, but unless tested, I simply won’t know.

Footnote: If you’re a Fiasp user, I’m trying to collect together user experiences so that they can be shared with those who are interested. You can find the submission form here. The responses so far can be found by following this link.


  1. This is a bit off the point but I would just like to know how you can see to insert into your lower back? Apart from that, thanks for the interesting updates on Fiasp.

    • Hi Jill, thanks. Glad you’re enjoying them. It’s purely use of a mirror and a sense of touch! That’s about it.

      • by me, even on 0 fat cannula insertion place absorption is very fast, even on a 3rd cannula day. Will extend 2-3 Days and see how it goes.

      • Less scarring?
        I’m finding that as I enter my 34th year with the condition, scarring matters a lot, and its signature can be subtle to detect. Slower availability of activity, (pocketing) and even a longer DIA with Loop often becomes appropriate. And its on a continuum. Is this an exacerbation of something FiAsp specific by site variation?

        • I don’t think so. My midriff area is one that, in 27 years, I hardly injected into and has only has pump sites for roughly 18 months. As a result, I don’t think it has had the opportunity to scar that much yet.

          In addition, the site life is pretty consistent, which isn’t what I’d expect of scarring.

  2. Tim,

    Slightly off the subject, but there seems to be a problem that I’m not getting any email notifications, even though I had checked the two boxes on your previous subject related to Fiasp.

    So when you reply to this comment I expect to get an email notification since I’ve checked the top box …”Notify me of follow-up comments by email.”

    Looking forward to your ongoing testing, and I expect to start on Fiasp later next week when my DSN returns from holiday. ….. Jon

  3. Referring to the top graph where BG went from 7 to 13 in ~ 30mins, then the Fiasp kicked in and BG reduced from 13 down to ~7 in about 1 hour, what would that have looked like using Novorapid?

    The graph doesn’t show when you had carbs or bolus but I assume it was about 00:00?

    • Yes, about 11.50pm. 85g carbs and 8u fiasp. With Novorapid, the insulin wouldn’t have kicked in until about 45 mins had passed and the slope would have become less steep before dropping away at about 75-90mins.

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