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[IP] Target BG; was Re: Corrections
- Subject: [IP] Target BG; was Re: Corrections
- From: "Richard Aleksander" <email @ redacted>
- Date: Sun, 9 May 1999 07:44:34 -0500
On Sat, 8 May 1999 20:45:45 EDT Robin, email @ redacted wrote
Subject: [IP] corrections
>Should the correction be the same as the meal bolus? For example. We left
>the hospital with a 15:1 carb ratio and a" "above 15 mg/dl correction (over
I think something was left out of the area in "quotation marks".
But the figure you seem to be searching for is the change in Blood Glucose
(mg/dl) resulting from the bolus change of +/-1 Unit of Insulin. For most
people I believe the figure averages 40 mg/dl:1U insulin.
For more advanced control freaks :-), I would point out that these figures
should not be considered sacrosanct or set in concrete.
For instance, I regularly infuse at twice my normal ratio if my blood
glucose is way above target (120 mg/dl or more ABOVE Target). A simple
explanation is that at bg levels above 250mg/dl there may be insulin
resistance owing to perhaps a rising level of glucose or some other cause,
and the excess bolus is needed to cover the incoming rising glucose in
addition to the glucose already present.
This I consider one of the most valuable pieces of information I learned
from reading this list.
Also, if it is found that the presumed infusion ratio does not reliably
result in the desired BG change, the ratio should be adjusted.
>But now, we are down to 12:1, does that mean the correction
>should now be for every 12 mg/dl over 160?
Probably not. Beyond that, these ratios are not necessarily tied. That is,
changing the number of units of insulin you need to infuse to cover 12 grams
of carbohydrate (from .8, as it was originally, to 1, as it seems to be
now), does not necessary mean that a unit of insulin will drop your mg/dl
less than you thought it would.
This is something you can experiment with empirically, and get the answer
The three ratios you seek are 1) Units of insulin/change in mg/dl blood
glucose, 2) grams Carbohydrate/rise in mg/dl blood glucose, and 3) Units
Insulin needed to cover measured weight of carbohydrate. The first two are
measured, the third is computed using the results of the first two.
Here is a Sample suggested PROTOCOL: On an empty stomach, take bg with your
1) above target, bolus measured amount of insulin and measure drop in bg at
specified time period later (dependent upon the type of insulin you are
using). Divide number of Units Insulin by the drop in bg (mg/dl) and you'll
be closer to knowing the second figure you mentioned.
In example, I would look for the desired change to show up with Humalog in
an hour or so, but I would not expect the change to appear as quickly with
regular insulin. Humalog is a nearly ideal insulin to use in pumps, as long
as you don't have side effects.
2) at or below target, take measured amount of carbohydrate, I.E., 16 or 12
or 8 or 4 grams of glucose tablets and measure rise in bg over time, say
1/2-3/4 hour. This will give your rise in mg/dl per specific amount of CHO.
Now bolus the amount of insulin you want to test to cover the mg/dl, say
1U/30 or 1U/40mg/dl, and test later to see how close you got. Do the math
to obtain an equivalent number of mg/dl both for grams CHO, divide them to
eliminate mg/dl and the quotient will be your particular units Insulin/grams
I might also add that it seems to me that pumpers on this list who are using
1Unit Insulin/12gCHO usually report a change of BG of 30mg/dl:1Unit Insulin
more than those who use 1U:15g.
I'm going to the data section of the insulin pumpers web site, to see if
these ratios are reported. RESULT of my search: It's not there yet. It's
also likely to be in Pumping Insulin by John Walsh, but I haven't looked
Also, I question setting your target to 160 mg/dl.
This will result in somewhat higher blood glucose levels than I would like
to see. I believe at a minimum this will result in Hemoglobin a1C over 7%,
or out of range considered good control.
Your team probably set your target at that range mindful of past incidents
I see a lot fewer hypos now that I use the pump (like none that I have not
personally gotten under control using glucose tablets).
It is possible to be more aggressive and even precise moving toward a lower
target and still avoid hypos using the pump and Humalog.
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