You're an engineer, so you want to measure things. That's quite correct, and you're obviously taking time to read up on the condition, but remember that, while you can measure and balance insulin/food/exercise, there's a lot of things going on in the background which can upset that balance and simply can't be measured or controlled with existing technology. That sounds a bit negative, but all I mean to say is that when you think you've done the sums right but it still goes wrong, it's not really your fault - there's too many random factors, so, as long as we're right most of the time, that's good enough.