[Previous Months][Date Index][Thread Index][Join - Register][Login]
[Message Prev][Message Next][Thread Prev][Thread Next]

Re: [IP] carb counting



On Fri, 21 Nov 1997, Ruth Elowitz wrote:
> Could you share (perhaps again I'm afraid) the "unused insulin rule"?
> 
Sure.

Let us use (for example) REGULAR insulin.  
If you look at the little chart that comes in the bottle, you will see 
that the insulin peaks in your bloodstream in about 2 - 2 1/2 hours and 
is down to residual levels in 4 - 5 hours.

A simple model can be built that says (and works pretty well)
that the insulin goes into your bloodsteam LINEARLY over four hours for 
the purposes of calculating the effect on your blood sugar.

That stated, a concrete example would be as follows:

Let us say that your blood sugar is 150.
That one unit of insulin moves your blood sugar down 50 points.
So.... under the circumstances, you would do a high blood sugar bolus of 
one unit and in about 4 hours or so you would expect your blood sugar to 
be 100 points.
You would also expect by looking at the model that at 
one hour down 12 1/2 points
two hours down 25 points
thre hours 37 1/2 points
four hours 50 points.
- --------- that said,
let say you eat and bolus 5 units (remember we are modeling REGULAR)
1 hour later you don't feel so good and you check your bg's and find out 
you are 50 when you are really supposed to be 100  oops!!!!
you have three hours to go and you're going down at 50 points and hour.

What to do??  eat a snack or take glucose every half hour for the next 3 
hours until the insulin is used up.

Simple!

For HUMALOG, all the times are cut in half.
It peaks in about an hour and is gone from your system in 2 to 2 1/2 hours.
You can use 2 hours for the purposes of calculation.

- -------------------------
Now, lets suppose that you eat, bolus 5 units of REGULAR and for some 
reason you check in an hour and find out you're 200.  OOPS!!!

I wouldn't be real agressive, you should probably be a little more than 
100 depending on what you ate. But !!! you are going up at least 50 to 75 
points an hour!!! Need to get some more insulin in to conteract the high.

This is the corallary to the unused insulin rule, the unused FOOD rule.  
The food will keep on digesting and pumping sugar into your blood.  There 
must be insulin there to allow you to absorb it and store it in your 
liver for later use.

Again, with HUMALOG, the times are all cut in half.

Some tricks!! if you are high, in addition to a hbs bolus, you can bolus 
the next hour's basal rate and set the pump to zero for an hour.  This 
will accelerate the bg fall without any risk of a low.

i.e. if you are 200 and bolus 2 units of HUMALOG to bring you down, in 
one hour you would only be at 150.  If you have a basal of 0.3 say, and 
bolus the 0.3 NOW, you get approximately 1/2 NOW.  If you were running a 
square bolus on a 507 ( or a temp on a 506) for a meal and it was say
1 1/2 units per hour, you could shoot in the whole thing NOW and about 
half would affect your bg early. i.e. you could get down to about 125 - 
130 within 1 hour.

Better yet, say you are high before a meal, bolus the hbs bolus + 1/3 of 
the meal bolus, you can probably eat in 45 min to an hour.

My meal high bg target for Lily allows her to eat ONLY when her bg is 
160 or below (the level where kidneys spill sugar). There is no point
in eating when higher than this, you body just has to work to get rid of 
the POISON sugar.  This technique usually allows her to eat pretty much 
with the family even if she is high when checking 30 minutes before a meal.

Michael