My son is type 1 and frequently eats breakfast late followed by lunch about 3 hours later.
He is on MDI novorapid and has a Libre 2 with MiaoMiao attached so that we can get more accurate and frequent readings.
Normally what happens is this:
- I check BG/sensor reading and it is on the high side but falling slowly (usually ~3hours post injection), usually around 7-10mmol.
- When calculating food dose I do not add on a correction for the high BG as I assume that there is still insulin working which would have brought him back into range had he not had a meal early.
- You can also calculate the amount of rapid insulin left in the system, but I don’t usually do this as we frequently check CGM data and make adjustments if necessary.
- If BG was unusually high (or low) I would adjust the dose accordingly by either increasing or decreasing insulin, and at this point I would calculate how much more insulin is left in his system.
This works for us, it is not meant to be advice as our situation may be very different to yours.