Minimed bolus wizard

Has MM figured out that a decimal point would be useful on entering the CARB ratio into the Wizard. I have been using my pump for several years and have a ratio of 6. Maybe 5.5 would be more accurately.
Have they put this capability into new pumps. Do other pumps allow more precision in this very important ratio number. Using whole numbers puts about a 20 % lack of precision in the bolus dose.

you can combine the carb ratio with the insulin sensitivity factor to micro adjust the dosage if it is really worth it. The formula for the wizard calcs are in the documentation. I agree with Dave tho, it does seem like overkill

Ah hell… I can’t reply to this without it turning into a rant… I’ve deleted my post 2 times already :slight_smile: In summary of my rant… I’m not average and I get pissed off when I’m told it’s my problem that I’m not :slight_smile:

Can you share details on how to use ISF to micro adjust. My I:C ratio is 1:6 approx. more like 1:5.5.

There are two techniques I can think of. One, set the lower and upper BG targets to the same number. Two, set the limit and I:C ratio lower/higher than actual to compensate. But I’ve never worked through the numbers to figure out how this might work.

  • Jeff

Sorry Jeff, definitely didn’t mean to blame you for anything… my thoughts were that the results may not be worth the effort… as far as the calcs go, the formula is published in the documentation, just plug your numbers in and adjust the ISF until you get a number that matches the ratio of 5.5 as opposed to the ratio of 6

I use a 522 , MM’s last model …would it work for you to look at different carb ratio’s …for your 3 meals and during the night ( if you happen to snack at 1 am ) …I have mine at different ratio’s . One can manually override any insulin dosage .
And please , someone explain , what ISF stands for …thanks

ISF = Insulin Sensitivity Factor. An ISF number tells you have far every unit of insulin will drop your blood glucose.

For example, if you know that your ISF is 1:40 and you want to bring down a BG of 190 to 110, then you would take 2 units of insulin to do this. Here’s the math: (190-110)/40 = 80/40 = 2.

I find this doesn’t work if you want to use the ISF for its intended purpose of accurately calculating a correction, and is only a partial solution to give a little more/less bolus. For someone with a low I:C ratio, this is a huge concern because it means the bolus may be off by a couple of units of insulin, or enough to result in moderate to severe hypo/hyper.

For example, my I:C is 1:5.5, I use 1:6. My ISF/CF is 1.6mmol/L (29mg/dL).

If I eat 100g of carb… using 1:5.5 this gives me a bolus of 18.2u.

using 1:6 this gives me a bolus of 16.7u, or 1.5u under the required. Given my CF of 1.6, this means that I will be 2.6mmol/L (46mg/dL) over my target. This is a large error.

The larger the carbs the more pronounced the error is. ISF/CF doesn’t help here if I’m on target when I use the bolus wizard. Yes, I can set my target artificially low, but then I’m in trouble if I use the bolus wizard to do a correction without carbs because it will overcorrect and send me very low.

To use the pump bolus wizard as directed means eating in much lower carb quantities to reduce the absolute error… so adjusting my life to fit the pump, not adjusting the pump to fit me.

The workaround that is best is probably to leave the CF set accurately and then underestimate the carbs by the percentage required (6 / 5.5 = 109%). And this is what I end up doing on large carb meals.

100g * 1.09 = 109g approx or 18.2u.

This approach works, but if the adjustment factor for the carbs isn’t an easy number (like 10%) then you end up rounding off to the nearest magic number and incorporating error into the process that doesn’t need to be there.

Ah, I see what you are saying now. I don’t think there is a way with the minimed to perform that calculation. Since it looks like you’re going to have to do the math in your head, it might make the math alot easier if you could use a correction factor of 1.1 instead of 1.09. Hope you can figure out a way to make it easily work for you!

In fact, yes, I do use simpler numbers and 1.09 was just for illustration. A really good presentation on this and other issues can be found in the following presentation by Walsh (author of pumping insulin)