In the USING INSULIN book John Walsh says that 20% of a dose will be used each hour after it is given, which leaves the active insulin length at 5 hours.
In the THINK LIKE A PANCREAS book Scheiner states the most precise method for Humalog/Nololog uses a 4 hour active insulin length, but says on page 133 that at 1 hr - 70% active, 2 hrs - 30% active, 3 hrs - 10% active. It looks like the curve is closer to the insulin graphs I see.
He also lists an aggressive calculation easy method of 67% at 1 hours, 33% at 2 hours and none at 3 hours.
or a Conservative calculation of 25% each hour used: 75% active at 1 hr, 50% at 2 hrs, 25% at 3 hrs, and none at 4 hrs.
Which of these do you use - and why. Or do you use another way to determine the calculations?
Do you have index cards you carry with tables on them, or do you use a calculator - or do you use your brain? Mine is usually fried - ha!