I'm still trying to make a decision on whether to upgrade my MiniMed
Paradigm 511 to the 512. One of the main features that the 512 has that the
511 doesn't is the Bolus Wizard feature. Part of the functionality of this
feature depends on MiniMed's interpretation of the time activity profile of
Humalog insulin. From what I've read here, it seems that there is a wide
variation in the way that each individual responds to various insulin
therapies. Is this true of the absorption of insulin? Does anyone know if
the time activity profiles given by Lilly and/or MiniMed are in vitro or in
vivo?



Thanks for your help!


--
Antonio
Age 37, Type 1 for 10 years
On Insulin Pump

Juan,
I am also T1 (20 years), but I have not yet gone to the pump. I do know,
however, that absorbtion of Humalog varies from person to person. The other
insulins' peaks, valleys, duration and absorbtion also vary person to
person. Heck, they vary day to day in the same person. The variations
don't vary by much, but they do vary.
Unfortunately, I do not know if the profiles are in vitro or in vivo. There
is a pumpers' use group. I've seen the address here several times, although
I do not have it. Their are several people here and at misc.health.diabetes
that will probably have some good insight into your questions.
Good luck in your decision.
Steph

"Juan Antonio" <noticias@pacbell.net> wrote in message
news:OtMjb.1156$KT5.509@newssvr25.news.prodigy.com ...

Since "in vivo" is all that matters, YES, decay time will vary with the
individual. That's one of the things that would put a monkey wrench in
your reliance on ALL of the 512's parameters for calculating your
boluses. If Humalog lasts in you for the time that Minimed expects,
then it'll work, if not, then taking boluses closer together than ABOUT
4 -5 hours could result in a small miscalculation. I doubt it would be
substantially incorrect, but it wouldn't be PERFECT. I'd give their
tech support a call and see how they explain that feature. Dr. Biggs
responded to this issue yesterday and agrees with my assumption that
there is no way to change the default setting for "active insulin", at
least in the current version of the firmware for the 512.

All in all, I think that unless you are taking large boluses frequently,
the whole idea of "active insulin" calculations shouldn't be much of a
downside. I'm anxious to see what Dr. Biggs thinks of this "issue".

dave

Juan Antonio wrote:

"Juan Antonio" <noticias@pacbell.net> wrote in
news:OtMjb.1156$KT5.509@newssvr25.news.prodigy.com :


The quick answer to your question is yes, but I doubt that it matters much.
The measurements are in vivo. Slow answer follows.

There is a significant amount of inter and intra patient variability in
insulin absorption. The variability is greatest in the longest acting
insulins and least in the shortest acting insulins. It is difficult to say
just how large the variability is because there are a number of methods by
which you can measure insulin activity and the choice of method will affect
your result. The methodological variability gets added to the population
variability. There are also difficulties in accurately determining the
duration since the cut off point is a little arbitrary and you can measure
"effective" or "clinical" duration or duration to the absolute limit that
your technique allows.

Minimed has chosen a conservative approach in that they have adopted a
duration on the long end of the data spectrum. It is a little difficult to
call a cut off time from their graph, and even if I had the data we could
argue about clinical relevance as the insulin levels get very low. In any
event, call it somewhere in the 6-8 hour range. Using that duration, any
errors in dosing a bolus close to a previous bolus will tend to undershoot
by a small amount.

When pumping rapid acting insulin for bolus, a problem that can be
encountered is postprandial hypoglycemia due to the insulin arriving in the
blood stream before the offsetting blood glucose. This can happen if the
overall glycemic index of the meal is low, a relatively low preprandial bg
level is not correctly factored in, or there is unaccounted for insulin
still being infused from a previous bolus. The conservative absorption
curve is, I suspect, aimed at this last cause.
As I said, this will produce slightly higher postprandial bg values for a
short time, but they will probably be better than those produced by the
manual alternative we use which is called a "dual" bolus in the MiniMed
terminology. The adjustments on the timing of the "square" portion of the
dual bolus are fairly coarse.

In any event, I suspect (I have not run any numbers) that the errors
introduced by the conservative duration estimate will be swamped by normal
carbohydrate content estimation errors.

Charly Coughran
ccoughran@DELETE-TO-REPLY-UCSD.EDU

--
Antonio
Age 37, Type 1 for 10 years
On Insulin Pump
"Charly Coughran" <ccoughran@DELETE_TO_REPLY_ucsd.edu> wrote in message
news:Xns94178DC8C7C7Accoughranucsdedu@132.239.1.22 1...

Charly,

Thank you very much for your comprehensive reply. Not only was it
informative, but your explanation that a slight variability in the time
activity profile would not make a significant difference was helpful. I'm
pretty much convinced that I am going to get the Paradigm 512 upgrade. Now
I just need to convice my doctor that there will be enough of an improvement
in control for him to write a letter of medical necessity for the upgrade.
(Any ideas?) According to MiniMed it does improve control, and I have a
message in to them asking if there is any data to support this.

--
Antonio
Age 37, Type 1 for 10 years
On Insulin Pump
"Charly Coughran" <ccoughran@DELETE_TO_REPLY_ucsd.edu> wrote in message
news:Xns94178DC8C7C7Accoughranucsdedu@132.239.1.22 1...

While the better matching of the Paradigm 512 bolus wizard to rapid acting
insulin compared to a manual dual wave bolus should theoretically improve
control, I would be very surprised if it rises above the noise level.
There are so many variables most of which seem to me to be much larger.

I've never seen any reports of carbohydrate counting accuracy among
diabetics using the method, but arguing from the published calorie counting
accuracy among dieters it is probably not all that good. Dollar for dollar
a kitchen scale that weighs to a gram and its diligent use for everything
that goes in your mouth would likely out do an incremental bells and
whistle improvement in your pump.

Given the increase in competition in the pump world over the last few
years, I think we're going to see frequent model changes with some
additional cute feature each iteration. Your insurance company is not
going to go for a change at every new one. I would be tempted to hold my
guns for a substantial improvement. Of course, I have a 507C and haven't
seen any reason to try to move up yet. My bias is that I like to drive and
I'm waiting for a fully independent, continuous bg level, feedback driven
control system coupled with the pump before I give up my control. The
partial feedback systems are, IMHO, more flash than substance.

I will none-the-less wish you the best of luck with your doctor.

Charly Coughran
ccoughran@DELETE-TO-RESPOND-UCSD.EDU



"Juan Antonio" <noticias@pacbell.net> wrote in
news:JMYjb.1228$BF1.457@newssvr25.news.prodigy.com :

Thanks again for your input. Since this is only an upgrade that I'm asking
my insurance for, I'm not worried about missing out on a new model in the
near future. Also because I think MiniMed has introduced about everything
they can for the short-term. From my reviews of the other pumps, it would
take something earth shattering for me to want one of them, which I don't
see happening.

I got a message from my MiniMed sales rep saying that there is a study which
shows improvement in control with the Bolus Wizard. I think that alone will
be enough to persuade my doc to do the letter of medical necessity and I'm
optimistic that it will convince the insurance company to at least reimburse
me 80% of $450.

--
Antonio
Age 37, Type 1 for 10 years
On Insulin Pump
"Charly Coughran" <ccoughran@DELETE_TO_REPLY_ucsd.edu> wrote in message
news:Xns9417A724FC389ccoughranucsdedu@132.239.1.22 1...

On Fri, 17 Oct 2003 21:01:29 GMT, "Juan Antonio"
<noticias@pacbell.net> wrote:


Minimed was making claims that the 512 improves control over the 511?
or that pumping itself is what improves control?

Mack
Type 1 since 1975
http://www.alt-support-diabetes.org
http://www.insulin-pumpers.org

In tribute to the United States of America and the State
of Israel, two bastions of strength in a world filled with strife and
terrorism.

According to the voice message left by a MiniMed sales rep, there is a study
that shows improved control with the 512. I returned her call and left a
message asking her to send it to me. Although I'm skeptical about anything
MiniMed does, I am hopeful that this will give me the backup I need to get
my doctor to write a letter of medical necessity, and my insurance to
reimburse me for the upgrade from the 511.

I'll start a new post here once I receive the information.

--
Antonio
Age 37, Type 1 for 10 years
On Insulin Pump
"Mack" <asdnospam@example.com> wrote in message
news:1hc3pv4n6tdfjtjgc3b6846qki3ldq474m@4ax.com...

"Juan Antonio" <noticias@pacbell.net> wrote in
news:jQ0kb.1264$er3.355@newssvr25.news.prodigy.com :

It would be helpful if you asked your pump rep for the citation and post
it. It would be nice to know the magnitude of the improvement and the
study condition under which it was seen.

I will definitely post this information once I receive it.


"Charly Coughran" <ccoughran@DELETE_TO_RESPOND.ucsd.edu> wrote in message
news:Xns94197AD462600ccoughranDELETETORES@68.6.19. 6...

On Sun, 19 Oct 2003 01:17:51 GMT, "Juan Antonio"
<noticiasNOSPAM@pacbell.net> wrote:


okay. you should also ask minimed how far the new pumps "warranty"
will be extended over the old one. and have that data included in the
letter somehow.

Mack
Type 1 since 1975
http://www.alt-support-diabetes.org
http://www.insulin-pumpers.org

In tribute to the United States of America and the State
of Israel, two bastions of strength in a world filled with strife and
terrorism.