Happy new year!

I am just hoping for a Happy 2016 for everybody here.

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Pre-bolusing: the logic behind it is as follows.

A normally functioning pancreas reacts immediately to any rise in BG. As soon as BG starts to climb, the pancreas releases insulin and it begins working right away, so BG never climbs very far.

Exogenous insulin doesn’t behave like that. Because it has to be absorbed and then introduced into the bloodstream, there is a lag, or gap, between the time the bolus is administered and the time it actually begins to take effect. So the idea behind pre-bolusing is to administer the insulin and then time the meal such that the insulin starts working just as the digested food begins to raise BG. That’s as close as we can come to mimicking what a healthy pancreas does.

Now here’s the catch. (You knew there’d be a catch, didn’t you? :wink:)

Different insulins begin working at different speeds. Fast-acting analog insulins kick in sooner than, say, R, and even the fast-acting ones vary from type to type. But it gets even worse: the same insulin can have a different response time in different individuals.

You need to determine how soon your insulin begins to work for you, and the only way to know that is by testing. Once you know that, you can plan meals and boluses so that they coordinate smoothly with each other.

Example: I know that R begins working about 40 minutes after I take it. So 40 minutes after a bolus, I sit down to eat. Doing it that way, my BG seldom rises above 115 or 120 and by the time two hours go by, it’s back down where it belongs.

The bottom line, as with most things pertaining to diabetes, is that each person’s physiology is individual. You need to figure out the protocol that works for you, and then do what works.


That’s what I was trying to say! The only thing I would add is that even in the same person, subcutaneous insulin action will vary from meal to meal. We must acknowledge and factor in variability. That’s why a CGM is so useful. So many people think blindly following a 15-minute pre-bolus regimen is all they need to do.

Edited to replace delivery with action.

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Thanks, David_dns, for your very clear explanation. For the record, I take Apidra as my fast-acting insulin. Fifteen minutes for pre-bolusing works pretty well, but I haven’t done any rigorous testing. I do know that after-meal bolusing always leads to high spikes. I eat rather slowly, so who knows how that complicates things.

Terry4 and rgcainmd, I appreciate your comments as well. I wish I could use a CGM–I’m so envious of people who have one–but I can’t use either a pump or CGM because I lack the real-estate. Years ago when I had a pump I did better because of the extended boluses. I’m thinking of experimenting with taking what I guess to be half the insulin I need at mealtime as a pre-bolus, the other half after finishing the meal. I could also try taking a 20 minute pre-bolus. Right now I can just see my A1C creeping up and up…