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[IP] Insulin Pump differences from user's perspective...



Mark Wrote:
Animas takes IOB into consideration in nearly ALL Bolus dosage calculations...
Medtronics, on the other hand, even in the instruction manual for the Paradigm
Revel pump, states that "If BG reading is below desired range, Active Insulin
(IOB in Animas terminology) is DIS-REGARDED in Bolus calculations."

Ricardo Responds:
Hi Mark,

I have been off line for a while, so I apologize if this has already been
answered.

How the pump uses IOB in its calculations and which pump manufacturer uses IOB
properly, is a subject of philosophical debate. Putting the philosophical
debate aside, technically MMbs approach is the most accurate from a textbook
definition of IOB.

IOB was intended to prevent stacking of _correction boluses_, not meal
boluses. MMbs approach assumes that the active insulin is covering a
previous meal and even though the current BG is below target, the BG will
eventually start to rise. The MM approach assumes that you have done your carb
counting accurately, taken into account any effects of exercise, stress,
hormonal changes, etc. and does not allow for much room for error.

Animas on the other hand takes a safer and some would say a more _real world_
approach and allows for carb counting and other bolus calculation errors when
you are below target. Animas deviates from the textbook definition and applies
the IOB to a meal bolus when below target.

Who is right is where the philosophical debate comes in. Take a look at the
following scenario:

You are slightly below target and eat a relatively high carb/ fat meal which
requires a substantial bolus. Shortly thereafter, you continue to graze and
each time you graze you do your bolus calculations. The fat is slowing the
metabolism of the carbs so your BG remains below target for an extended period
of time. The Animas reminds you that you are below target and have a
substantial IOB and suggests that you do NOT bolus each time you put something
in your mouth, no matter how many carbs you eat. After a while, your BG starts
to increase above target, so now the Animas suggests a bolus.  Many of us
would go high eventually due to all the unaccounted for carbs while below
target and the pump applying IOB to the grazing boluses. In this same
scenario, the MM approach would have covered all your carbs and hopefully
prevent the eventual high

The Animas approach is safer and the zero bolus recommendation can be ignored
at any time, but the MM approach is technically correct. I use an Animas and
there are times that I am below target and it recommends no bolus, but I
override the recommendation because I know what I just ate and my BG will
eventually rise. Alternately, I will ignore the zero bolus recommendation, but
extend the bolus to bring the insulin on board more slowly. The MM bolus
recommendation can also be overridden when below target.

I think both approaches to IOB have merits. In previous threads, some IP users
have voiced their discontent with the MM approach. I think IOB is one of the
most critical decision points when choosing a pump. Whichever pump you use,
the key is to understand your body, how your pump calculates IOB and close the
loop with your own decision o;?making for your boluses.

Don't belive the hype. There is no such thing as a smart pumps, so we have to
be smart diabetics.
.
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