# Insulin sensitivity factor questions

I need some help in understanding ISF. I know that it reflects how much my bs will drop using 1u of insulin. My pump is set at 50 which I’ve always thought has been high because I have frequent lows. So…I recalculated and came up with 73. My question is when I’ve been bolusing before meals I’ve been comparing the calculations…seeing what my bolus should be based on an ISF of 50 and then of 73. What has me confused is that when I use the ISF of 73 (using ezCarb) the bolus shown is higher than when the ISF is 50. The opposite was true when I did a correction bolus earlier today…which if my understanding of ISF is correct makes sense. Am I missing something? Thanks!

The ISF is really just for correction. So yes, when you correct with 73 vs 50 as your ISF, you will be doing less insulin.

Your EzCarb meal bolus is computed based on your I:C ratios, not your ISF. (How many carbs you can cover with one unit of insulin).

I thought that might be the case but then why is ISF displayed when I’m entering my bs when doing an ezCarb bolus? If it’s only based on I:C ratio why does the calc change when I change the ISF? Thx for the reply.

When you to an ezCarb bolus, it actually is doing multiple calculations at the same time.

First it uses the number of carbs you tell it your going to eat, divides it by your I:C ratio and gives you the amount of insulin needed to cover the carbs.