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Re: [IPk] Timesulin query



Joel,

Interesting speculation.
An alternative, but equally speculative, speculation might be that the
more frequent though smaller drips of insulin coming through the
cannula as a result of the more frequent basal delivery is slowing
down the clogging.
Probably this is off only academic interest, but two factors might
help distinguish between the two conjectures.
Firstly what are your basal rates - you wrote that you use about
18-20u basal a day - 18u a day, if constant basal, would correspond to
0.75u/hour, which would be delivered every 3 minutes with a Vibe, and
with the 522 about every 8-9 minutes (divide the rate into drips of
0.1u and give them uniformly distributed over an hour) - so there is a
difference there.
Secondly the Vibe has 2 options for bolus delivery - normal (1u every
second) and slow
 (1u every 5 seconds) - you could test (which you probably don't want
to do!) if going over to the slow would make a difference.
But, aside for academic interest, the only other reason for wanting to
know would be to know what factors are important if/when you need to
make a choice about another pump.

Aside from this your comment about clogging and cannula life is
interesting. Since switching from the Cozmo to the Vibe, I have more
frequent problems with sets going bad after 1-2 days, instead of
generally lasting 3 days. I am also using somewhat more insulin. I use
Humalog, which you write is less prone to clogging than Apidra. I also
use the same sets (also Comfort). I think basal delivery is identical
- but I'm not sure because the Vibe gives one those strange warning
messages when one sets temp basals, saying Minimal basal rate limited
to 0.025u/hour - sometimes when it is not set to less than that, and I
wonder if it is really reporting a rounding error, and should be
saying that you have requested a basal that is not an exact multiple
of 0.025u/hour, and more than that I want to yell at it and demand
that it tell me what basal rate it is in fact delivering. But one of
the few things which is different is bolus delivery - it seems to me
slower than on the Cozmo, and as a result of your comment I have just
gone to the setup menu on my Vibe and noticed that it is set to slow -
had assumed it was normal - now it is - so I can be a guinea pig for
the test I proposed above and lt you know if I have fewer problems
with bad sets before 3 days now that I have switched to the faster
deliver option - let's hope so! and thanks for drawing my attention to
this.

Nanette

On 14 March 2014 14:18, Joel Milner <email @ redacted> wrote:
> Nanette:
>
>  When I was pumping with the 522 I was self-funding CGM on a 24/7 basis using
> Medtronic Sof-sensors that I was picking up at reduced price from the "grey
> market" so I have had a good handle on my BGs for several years.
>
 > TBH the reduction in basal is something I do not really understand and would
> not have predicted in advance. I am using the same infusion sets (the Comfort
 > shorts are identical to the 13 mm Silhouettes). I suppose that the smaller
more
> frequent basal deliveries is a possibility.
>
>   Another explanation (although this is entirely speculation) is that it is
> connected to the speed of bolus delivery. I have always had problems keeping
> sets working efficiently. I use a 2-day rotation and with the 522, I often
> noticed that my CGM trace would be rising on night 2. I hardly ever see this
 > with the Vibe. John Pickup has presented evidence that one of the main causes
of
 > site degradation is the denaturation of insulin at and around the cannula
caused
> by reduced pH. This can cause partial clogging of the cannula and absorption
> problems. Of the three Analog insulins, Apidra (which I use) is much the most
 > prone to this problem. The Vibe delivers boluses very rapidly, whereas MM
pumps
 > take geological time to do so. Perhaps the rapidly delivered boluses are
acting
> to flush the cannula and keep it clear of denatured insulin.
>
> Joel
> .
> Follow us at https://www.twitter.com/insulinpumpers
> Make a long URL short at http://type1.org
.
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