I think the pre-bolusing tactic is one of the most overlooked yet highly effective insulin dosing tactics. I only used it occasionally in my early years with diabetes.
One of the things that held me back was when I used Regular for my meal insulin. Unlike the current rapid acting analog insulins, Regular had an onset time of 30-60 minutes, a peak action of 2-4 hours and a duration of 6-8 hours. Talk about an unruly tool to use! I once fell asleep after I took my meal pre-bolus of Regular insulin. When I woke up on the floor, I thought aliens had invaded my apartment!
So, this is still the main safety hazard with pre-bolusing. You just can’t lose sight of the fact that you took your dose! As we know, the phone can ring or someone can knock on your door and distract you from your intention to eat. I think setting a phone alarm is a good safety practice. The rapid acting analog insulins make pre-bolusing safer than it was with Regular.
Using a CGM to discern when your meal insulin dose starts to bend your CGM line down is a good way to learn what your ideal pre-bolus times are. For me, I need to pre-bolus a longer time for my morning meal than I do for my evening meal. My morning pre-bolus time is usually 60 minutes but sometimes I need to shorten this time and my CGM helps with this dynamic shift. My evening meal does well with a 30 minute pre-bolus time.
For those who use multiple daily injections, or MDI, just do a few fingersticks at dose-time followed by fingersticks every 10 minutes. You won’t need to do this for every meal into the future; you will learn a few safe rules-of-thumb that work for you. If you keep a record of this you should be able to make the pre-bolus tactic work for your own unique needs.