The idea - which I generally do for most meals - is instead of trying to take the amount that perfectly matches the carb total, take the amount so you have enough in the first hour to cover the meal. That prevents a spike.
This is somewhere around double, since the half-life of insulins like NovoLog and Humalog are about 1 hour.
( These highlights do not include all the information needed to use HUMALOG safely and effectively. See full prescribing information for HUMALOG. HUMALOG (insulin lispro) injection, for subcutaneous or intravenous use Initial U.S. Approval: 1996
See section on Pharmacokinetics, elimination and t 1/2:
These highlights do not include all the information needed to use HUMALOG safely and effectively. See full prescribing information for HUMALOG. HUMALOG (insulin lispro) injection, for subcutaneous or intravenous use Initial U.S. Approval: 1996 )
The rest of the insulin, hours 2-4 is “extra”. More than you need, it will drop you low after that first hour. You cover that with desert.
So total all the food (except dessert) and double it. After a while you start to drift low because you took too much, and then you have dessert.