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[IP] My Humalog report (lengthy)


In response to Michael's request, I will try to summarize some information
I have gathered from list discussions relative to issues with Humalog that
*may* be infusion site related. Please note that these summaries are based
on "anecdotal" evidence only, gathered over a period of time in discussions
on various mailing lists since Humalog was first made available. For now, I
will try to stay focused on reported problems with the infusion site, at
the risk of getting too far off track. My comments on apparent "rebound
highs" appear at the very end of the message. My apologies in advance for a
lengthy message and for some users, what may be an expensive one :-(

1)  Users note rising or erratic BGs toward the end of two or three days on
same set at same site. Most users note this as "not being able to go as
long with a set on Humalog as I did with (Velosolin or Regular)", or
generally report that they need to change sets more often. There is a
variance in the amount of time which users normally leave their sets in, so
it is difficult to draw a clear correlation here. It does generally appear
that sets must be changed more frequently with Humalog than with Velosolin
or Regular (closer to the *recommended* changing intervals - 48 hours
metal, 72 hours for "Teflon type" soft sets).

2)  A number of users have also observed they initially had no problems
going the entire "scheduled" time with their infusion sets, but now think
they are not able to go as long between set changes. (Sometimes expressed
as "Gee, it used to work great, but not any more"). I am included in this
category. I now find my BG excursions beginning after 1 1/2 days, rather
than after 2 days or 2 1/2 days. Sometimes these excursions begin after one
day. I currently use a set changing interval of two days. These excursions
are more frequent and more erratic for me with soft type sets. Bent needles
work the most consistent for me.

3)  There has been a good deal of discussion re: Humalog reacting adversely
to heat (more discussion on this during the summer months. Right now, not
much being said). This idea seems to have been countered by the "site loss"
theory. Examples cited which argue against the heat affecting Humalog's
potency have shown BGs coming down after doing a site change, while still
using the same cartridge / reservoir (only thing changed was the set and
possibly the tubing); injecting insulin removed from the cartridge by
syringe and having that injection return BGs to the target level.
Subsequent use of this same cartridge at another site resulted in normal
BGs for the user.

One possibility that may need some more investigation is whether the site
loss itself is accelerated during the summer months (warmer weather for
most of us). This may be mistakenly perceived as "Humalog losing it's kick
when it gets warm".

4)  Discussions re: total amount of insulin used affecting the rate of
onset of site loss (i.e., site loss happens more rapidly if you use more
insulin). This is also a difficult discussion to monitor, since there are
many variables to weigh. Users differ in body make up, site used for
infusion set, length of pump usage, length of time on Humalog, total amount
of time using insulin, rotation of sites before pumping, site rotation
since pumping, etc. No real in depth discussion here, consequently, no real

5)  Re:  Mixing of Velosolin (or Regular) with the Humalog may tend to
alleviate many of the issues summarized above. A number of users mix
Humalog and Velosolin in ratios ranging from 3 to 1 or 5 to 1. Most have
reported no problems with time of onset (still fast action), or "tailing"
effect from the Regular (Regular can take 4 to 5 hours to thoroughly
dissipate in your system, resulting in the remainder ("tail") interacting
with subsequent boluses or basals. In effect, a "double whammy", but not as
dramatic as often experienced with longer acting insulins like NPH).

I will be trying this mixture with my next cartridge change, using a
Humalog to Velosolin ratio of 5 to 1.

6)  Some discussion re: possibility of the tubing and / or soft cannula
affecting the Humalog, (possibly due to "leaching" of compounds from the
plastic material). Interesting thought but no clear consensus. I have
tested on myself by using the same tubing for six days straight, changing
only the cannula portion every 48 hours (Comfort sets). Result was totally
"flat" BGs, little post prandial spikes, and no BG excursions beyond 150
(essentially my target range). I don't know what to say about this. I don't
have enough sites to keep up this sort of rotation schedule.

7)  I think I have detected some tissue "build up" at sites. Tissue appears
harder, takes several days to return to "normal". This disappeared when I
returned to Velosolin briefly this fall for two weeks. With Velosolin, it
was virtually impossible to find my last site after removing the set. No
marks, no tissue hardening, etc. They were "clean".

re:  "Rebound Highs". I will see BGs in the 200 range which seem totally
unrelated to any other issues (normal meals, schedule, etc.). In addition,
there have been many nights when I have woken around 2:00 to 3:30 a.m. (my
traditional pre - pump "hypo danger time") with all the symptoms of a hypo
- sweaty, heart racing, etc. BG levels at these times were normal (120 to
150) yet on rising several hours later, hinted at a rebound effect (in the
200 range, tough to bring down). These BGs were high, stayed very resistant
to correcting boluses, etc. To test this theory, on several occasions I
responded as I normally would for a hypo, even though the BG was "normal" -
I used glucose tab(s), waited awhile, then returned to bed. Waking BGs were

I have experienced this during the day as well, but did not apply this
analysis to it until recently. These symptoms are very subtle, very hard to
catch if I am busy. I have verified and re verified basal rates- they are
fine and need no real adjustments (I use very low rates most of the day,
ranging from .2 for majority of day to my highest of .7 at 6-7 a.m.).

I am now suspecting that highs which are tough to bring down may in fact,
be related to rebounds from undetected hypos earlier in the day.

Thanks for your patience ;-)

Bob Burnett

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