Pre-Bolusing vs Over-Bolusing

How important do flat-liners here value (a) Pre-bolusing vs (2) Over-bolusing?

I am getting back into more aggressive pre-bolusing times (20 or 30 minutes compared to 5 or 10 minutes). I’m going to try to get more aggressive with my timing, but am also shaving off some of my over-bolusing. I’m testing whether the extra head start of the bolus will win out over needing so much extra bolus. I’m ultimately trying to get to the point where I dampen my meal spikes, but also tamp down some of the extra quantity of insulin I have floating around in my system at any given moment. My activity levels are so extremely variable on weekends due to having little kids that I really like to actively play with them at a moment’s notice without having what feels like a ton of extra bolus floating around in my system.

Thoughts? Tips?


To me, they aren’t really a one vs the other. They’re just different strategies I use (either both or just one) for different situations. I always pre-bolus, and sometimes I pre-bolus and overbolus. It depends on a lot of different factors - where my BG is at, what I’m eating, my activity level, etc.

If this is your goal, you are absolutely doing the right thing in switching to more pre-bolusing, IMO. I only ever overbolus if I’m eating something I don’t normally eat (extra carbs or straight sugary things), and I’m willing to eat even more when that eventual downward trend starts from the extra insulin. So, to me, overbolusing all the time would be extra insulin and lots of extra food all the time. Pre-bolusing is just a way for me to handle the day to day rises from food.

And I’ll add in my usual Afrezza plug - it makes life so much easier because I don’t have to pre-bolus. I use it for lunch and dinner most days now. :slightly_smiling_face:


As Emily said, they are different strategies. Hundreds of different scenarios where you might choose one instead of the other.

A few simple examples:

If you are at a restaurant or at a work function where the timing for the serving of food is not predictable or you aren’t exactly sure what is being served or how big the food portion is, a pre-bolus might not be very practical. So maybe over-bolus works better in that situation. You might have to wait until you see the food in front of you.

If you are at home, and everything is perfectly planned as far as the meal timing and the carbs in the meal, maybe a pre-bolus can work.

Lots of different situations, just experiment with them and see what works better.

For the crazy big meal where the timing is planned, like Thanksgiving, I like to use both of them.


To me, the pre-bolus is milder. It enables the meal bolus time to start working so that a spike doesn’t get too much of a head start.

I use an over-bolus to control what I expect would be a huge spike if I’m going to eat a large amount of a fast carb. For that kind of eating, a pre-bolus might not be enough. Basically, the pre-bolus gets a modest amount of insulin to be working near its peak activity, whereas the overbolus gets a large and increasing amount of insulin into the bloodstream, and it’s still ramping up at the time I eat.

A third member of these spike-control strategies is the “eating soon” technique. About an hour before eating, take the largest insulin correction possible that will bring your BG to your lower limit without sending you low. This gets some active insulin into your bloodstream to help sweep your carbs into the liver to make glycogen when you do eat. This helps moderate the spike. I consider it to be milder than the pre-bolus because it is a smaller amount.


I don’t know – for us, pre-bolusing never really worked so well. I think the issue is that our kid is so small that his digestion outlasts his insulin if we pre-bolus. Overbolusing and feeding the tail works much much better. With openAPS, we also have the option of superbolusing, which essentially means giving more of the insulin upfront. That does seem to work well but with that strategy we get a rise about 2 or 3 hours later – which usually openAPS is decent at catching.

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we’re big fans of “eating soon” as well. To me it’s similar to having a slightly higher basal rate than you need – it prevents the liver dumping of glycogen that happens when you first begin eating (before things even reach your stomach), even if the mealtime insulin hasn’t hit your system yet.


I use the “eating soon”, too, though I never knew it was called that!:wink: I accidentally came upon it, taking a correction an hour or more before dinner. Then I noticed that my after dinner BG was more flat. I almost always pre-bolus, even at restaurants if I’m pretty confident of the food content and serving time. Usually about 20 minutes if I have full control of the timing. I also over bolus for situations when I’m not sure of the food, as others have said. Sometimes my BG is already on the low side and trending down though, so I hesitate to take the full bolus needed for the food all at once. For those I’ve started taking an extended bolus so the effect of the majority of the insulin is delayed over a few hours, giving my BG time to rise at the beginning. This helps to keep my BG from going low during dinner, but it also tends to slowly rise during the dinner and a couple hours later. So I will often need to take an extra bolus an hour or two later. That might just be me, or the type of food I’m eating though.


Thanks for the great input, all.

One of the things I was most excited about when I started on Omnipod was the ability to take a unit an hour before a meal to nudge things in the right direction. I always wanted to do that on shots but couldn’t justify the extra poke.

Now that things are generally in a much tighter orbit than they have been in the last year(s), hopefully these fine-tuning techniques will get me the rest of the way to my goals more often than not.

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It appears that I was wrong about the mechanism by which it works. Thanks for the correction.

If insulin peaks around 1 to 1.5 hours, and some folks pre bolus by 45 minutes to 1 hour…does the food almost instantaneously cause BG rise?

How do you address “spontaneity”? For example, I simply wish to eat an apple? Help and advice greatly appreciated.

There’s a race between the release of glucose into the bloodstream by digestion, and the release of insulin into the bloodstream from the injection/pump. If the rates are perfectly balanced, the BG would stay flat. But in the real world, this is uncommon. Usually, eating causes a BG spike. So pre-bolusing is a way to give the insulin a head start, in the hopes that the spike will be smaller. That’s just a tool, nothing more.

Using your best estimate of the carb content, give a bolus and eat the apple. Expect the BG to spike and then come back down. If it doesn’t come back down below 140 within 2 hours, that’s a sign that the bolus should have been larger.

It’s up to each individual to decide what BG range they are comfortable with, and then to learn strategies to stay in that range as much as possible. For people who never want to go over 200 and would prefer not to go over 150, pre-bolus is a helpful technique. Another technique is to overbolus, i.e., give a larger than normal bolus with the intention of taking more carbs later to arrest the crashing BG. I’d say that strategy could be safe when wearing a trustworthy CGM with alerts that will help me stay out of serious trouble. Another strategy is called Sugar Surfing, which has been popularized by Dr. Stephen Ponder. It involves frequent checks of the CGM graph and many small corrections with insulin and carbs to gently steer the BG in a good direction. Hybrid closed-loop systems (pump + CGM + algorithm) attempt to automate this. They’re not great at it yet, but they can help significantly in keeping the BG in a good range when we’re not paying attention, (asleep, for instance.)

I don’t use a CGM. When I had the CGM, I relied on fingersticks because the CGM drifted. I don’t mind fingersticks because it’s more accurate anyway.

I cannot pre bolus a spontaneous apple or say a Kind bar…so overbolus may be the only way…except wouldn’t that lead to frequent eating/snacking? I’ve had situations where I overcorrected the low with more carbs. This led to up and down BG.

For the most part, I keep my BG between 110 to 170, it’s been running a bit high recently. I used to be able to keep it between 85/90 to about 140/150 most of the time. My morning Fasting BG have drifted up to around100-125. I used to be around 90’s.

The one major lifetstyle change is that I exercise less now than I used to. I still walk, but I’m not doing strength exercise. I prefer and enjoy walking. Aside from doing some squats for the glutes, I prefer walking. I have read that exercise is important for diabetics…still, I feel that at age 60…I wish to take it easy.

Any thoughts?

Do you use the split-bolus for slow foods like pizza? That gives some insulin up front, with the rest of the insulin later. That slows the insulin down. You could think of the opposite of that, split carbs. You bolus for all the food, but only eat part. Then later you eat the rest. That’s effectively the overbolus (for the first part) and the delayed carbs to use up the rest of the insulin without hitting your bloodstream too soon. Is it practical for you to eat a half apple and finish the rest later? (Try a half hour later, or 1 hour later.) That would effectively slow down the carbs.

Or you could look into faster insulins. Some folks have had good results with fiasp. Some folks have had great results using Afrezza to get insulin action fast.

My CDE used to remind me “If your BG is too high, you need more insulin.” If your BG is drifting upwards during the day and overnight, maybe you need a bit more basal. If I had BG drifting upwards I’d increase the basal just a little bit, and keep adjusting every 2 or 3 days until it was working to my satisfaction.

How long ago was your bad experience with CGM? If it wasn’t with the current best ones, maybe consider giving the new ones a try? They don’t have to be perfect to give you an overall picture of what your BG is doing, and thus give guidance on how to make adjustments to your insulin. Some folks just can’t get usable CGM accuracy with what’s currently available, but my impression is that the majority of people find them helpful after getting acclimated to their quirks and limitations.

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I should explain, my bedtime BG’s have been about 120’s-130s and my fasting have been similar, 120’s and 130’s. Therefore I tend to think that my basal is ok. I would like to somehow lower by bedtime numbers…

I’m hesitant o correct when I am between 120’s and 130’s…even 140. If 160’s, I would take a half unit correction using MDI. I don’t want to go low during sleep. Does that make sense?

On the over-bolus, it can reduce the spike, but you might go low later. And what would you do if you went low later? Eat some carbs.

What if you over-bolused, had the apple,and then an hour later as you were dropping, had another half of an apple? Or some sugar treat?

I think it is easier to stop a drop than turn a spike back down. So for me, an over-bolus is easier to fix with carbs an hour later, than it would be to bolus the right amount and have to correct a spike or sit above target for hours.

But…you have to correct the drop with the right amount. Otherwise you spike.

If you over-bolus:

  • know that you need to have access to testing and carbs later
  • don’t do it away from home when you don’t have access to your refrigerator
  • know that you might need to eat more, so this can be tough if you are trying to lose or maintain weight
  • know that if you are driving or performing brain surgery, this might not be a good strategy

Maybe try it and just have a snack later for the eventual drop. See how it works.

For dinner, I generally over-bolus, and have dessert later. Works great. You don’t need to have dessert right after dinner. Over-bolus, eat dinner, no spike, an hour later I start to drop and I eat dessert…


If your basal were adjusted slightly higher, rather than sitting at 120-130 for hours your BG would slowly drift downwards. I used that strategy, in moderation, to help stay in a lower good range.

If instead your BG really is hovering at 120-130 for hours, not drifting upwards from 120 to 130 to 140, then I would bolus whatever the right amount of correction insulin would bring me to 100. Because I wouldn’t want to be stuck at 120-130, I’d rather be stuck at 95-105.

Back when I was on MDI, I would dose as small as 1/4 unit, just by eyeballing it in the syringe. In an old thread Eric explained another way, involving the making of a vial of dilute insulin, to facilitate taking smaller doses with a conventional syringe. A third way, if you need 1/4 unit but it’s too difficult, you could take 1/2 unit plus a little bit of carbs to use up the extra 1/4 unit. That’s different for everyone, but maybe a half saltine? One raisin? Two peanuts? It depends on your insulin:carb ratio to see how many grams of carb you need for 1/4 unit of insulin.

I agree that we definitely don’t want to go low in our sleep. In my case the CGM alerts keep me out of trouble even if I overdo the insulin. When you don’t have a CGM to watch over you while asleep, it is sensible to be more careful.

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Today’s experiment was a cannoli. I hope the following is not too sloppy:

I pre bolused by about 20 minutes ( it was in the afternoon)
4:30 pm 4 units - bg 132 before the cannoli
5:30 pm - 1 hour after the pre bolus bg 113
6:15 pm bg 190
6:15 pm took 1.5 units for correction
6:20 pm bg 206 - WTH!! took a few sips of red wine -
6:45 pm bg 223 - WTH!!???ate dinner : salmon, steamed Chinese broccoli

7:15 pm - bg 205 - did the correction from 6:15 pm finally begin to work?
7:15 pm - took 1 unit for correction

8:30 pm - bg 166
11:30 pm - bg 129

I thought the 1 hour bg 113 was not bad. But then…wahh…

What would you have done differently? How would you have pre bolused, and bolused for the cannoli? It looks like 6 units may be the amount for the cannoli. If I had taken 6 units in the beginning, I may be concerned that my 1 hour number may become too low, 1 hour bg =113.

I wish that diabetes doesn’t prevent me from doing the activities that I would like to…however, I do feel as if I am experiencing diabetes burnout.

A big thank you to this wonderful community and all of your support.

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With only a few fingerstick measurements it’s hard to know exactly what was happening. But it sure looks like your BG started rocketing up about 40 minutes after you started eating, and that the 4u wasn’t enough. What I can’t tell is whether the 20 minute pre-bolus caused your BG to drop quite low and then when you measured 113 at 1 hour the BG was already racing upwards from the cannoli, or whether the 20 minute bolus just caused a gentle drift lower followed by the spike when the cannoli digestion kicked in. That makes a difference in deciding if you need less or more pre-bolus time in this case.

Excellent observation. The key is to draw the right conclusion. Stated nakedly, the concern is that “6u could be dangerous because I might get severely hypo by 1 hour.” It would be unempowering to conclude “6u is too risky to try,” because that reflects an attitude where you’re just going to take an insulin dose and hope it turns out ok. Empowerment comes from more data: more frequent BG measurements when experimenting with an increased insulin dose, starting sooner than 1 hour. That enables you to see if your BG is dropping too much, too soon, in which case you can simply take some glucose tablets to stop the fall—long before you get into trouble.