Timing a Bolus

I’m using Novolog for bolus now but having trouble figuring out how long before eating to shoot up. I’m still going to 170 or so for meals that would normally send me over 200, so progress, but not where I want to be. The flexpen says to use it 5-10 minutes before eating but I’m wondering if most people on MDI bolus earlier? I know we all vary but just wondering, how long before a carby meal do you need to use your rapid acting insulin?

Keep in mind that this is rather variable from person to person, so you have to do quite a bit of trial and error to figure out how your system works. To make it worse, it varies for an individual as well under some circumstances -- like being sick -- so tread cautiously, build your knowledge.

That said, I generally bolus Humalog 30-45 minutes before eating a carb meal between 30-60 carbs. If I'm going to be having a rare high-carb meal (special occasion out or something), I'll bolus 45-60 minutes ahead.

However, it's not that simple, actually. One variable in the equation is where my BG is when I start. If I'm high-normal (100-120) I'll go for the longer pre-bolus (i.e. 45 minutes vs. 30) -- the correction and meal bolus together -- and wait for my BG to drop 5pts or so before I eat, or when the 45 minutes are up, whichever comes first.

I also take into account how my BG has been "behaving" that day... Is is stubborn, showing unusual IR for some reason? Adjust pre-bolus timing. Also, often when it's like this I'll make sure to be really agressive correcting and getting it down into the 80's before I even consider a meal. If I'm too hungry, I play "chicken" with the insulin action, my BG level, and when I eat.

With lots of practice and experience, you can get very skilled at this. I'm able to stay under 140 now after lunch, starting in the 80s, every time I can time my bolus properly. Only when life/work/whatever doesn't provide that convenience (some times you can't control when you eat so carefully), so you just live with the 200 that day.

The other time is when sick. Depending on how hinky my stomach is, I might wait until my BG starts to rise before bolusing -- I've had too many episodes where I either ended up vomiting (and therefore no carb input), or simple had way slower digestion because of the illness (leading to a difficult to treat hypo).

I was thinking the 5-10 minutes seemed a little short. I know it’s fast acting but wondered if most people need to give it more time than that to kick in to stop the spike. I only need bolus now so I should usually be starting in the 80s, sometimes that worries me though because I think it will kick in too soon and I’ll go low (I’m hypo-unaware unfortunately). Of course, I know I have to adjust the dosage too and the glycemic index of what I’m eating also matters. Sheesh this isn’t easy, I look forward to figuring it out though and gaining back some weight and energy too I hope.

As Dave said, we are all different. But I generally bolus about 20 minutes ahead. I do seem to have some leeway as I sometimes am ready to eat sooner and sometimes things take longer. I always add in a correction if I'm over target before my meal. If I'm "lowish" though I don't subtract from my carb counted dose because I've found that if I don't bolus for the full amount of the carbs I will go high. What I do in that case is just bolus and eat right away. If I am a little low (as in the high 50s, low 60s) I might just eat and then test after eating and wait to bolus until I come into range. This is risky though because I sometimes forget for a while. If I am significantly low I will treat and wait.

Trial and error/trial and error and you will find what work for you in terms of BG but also in terms of your habits and what fits best for your routines. By the way my take on it is that glycemic index is fairly irrelevant for most Type 1's.

IIRC you're getting a CGM, right?

That makes it tons easier. Even so, 15 minute increments is about as fine as you need to get, in my experience.

5-10 minutes is definitely too short. Peak action doesn't occur for an hour at best, usually more like 90 minutes for most people.

Keep in mind that your gut will digest the sugars and dump them into your bloodstream much faster than you'll absorb the insulin you take to cover it. Within an hour the rate of glucose entry from the gut peaks, and then at the 2 - 2.5 hour mark, it's generally done. I.e., all the carbs you bolused for are now in your blood, but that humalog you took to cover it will take 4-5 hours to do its work.

As such, it's simply impossible to control BG as narrowly as the body does. Because of this difference in rate of action (glucose fast, "fast" insulin still very slow by comparison) PWD's have to play kind of a game of Chicken* with the insulin to get the best possible BG profile you're gonna get.

What you're trying to do is have the insulin action peak around the same time glucose starts to enter your bloodstream. "Peak" in this case means highest insulin concentration in the blood from your bolus. If you do it right, you'll start in the 80s, dip no more than 10 points or so from the pre-bolus, then start heading up from the food.

For me, carbs start to hit my blood about 15-20 minutes after I eat, and stop after about 2 hours.

Playing with that parameter, and my own particulars with humalog (time-to-peak 90 minutes, action tail 4 hours), I tweaked and adjusted and played until I figured out how to optimize the whole thing.

It's tricky, though. I risk hypo every time I have a meal because of the way I do this. One has to be attentive. I wouldn't push it as close to the edge as I do without a CGM. I always have a small baggie of 20 skittles in my pocket as a counter-dose if something interferes with eating -- once I bolus, I'm on a timer.

In your situation, starting out, I'd just pre-bolus 20 minutes, every time, and see what happens. Test @ 1 and 3 hours post-prandial. After you have a dozen or so datapoints, share with us and we'll help as best we can!

If you do get a CGM, you can run much closer to the edge.

I look forward to figuring it out though and gaining back some weight and energy too I hope
Oh, Lilly, you'll gain the weight, trust me. So long as, now that you can cover them, you eat a reasonable amount of carbs.

If you're trying to gain weight and have access to insulin as a PWD, I would recommend against a low-carb diet while you're trying to put on some poundage. 150-250g a day, thereabouts. You're not trying to make BG control easier by nutrition strategies right not -- you've been given that miraculous tool insulin to do that!

You will gain weight much faster for the same calorie load with a higher mix of carbs vs. fat and protien.

Finally, I know all this is a bit daunting at first. Wasn't that long ago for me (18 months) -- I remember. Rest at ease that it will get routine, and much easier. Also, the pump as a means of delivery makes a huge difference compared to MDI -- since it's so easy and unremarkable to the world around you when you take a bolus you'll do it anywhere, anytime you need to. I've had tough days where BG was so stubborn I bolused a dozen times, relatively small amounts, chasing the damn thing down.

I could never do that on MDI.

I’ve talked to a Dexcom rep, I thought she said she’d get back to me in 48hrs after contacting BCBS but it’s been a week, left a message today. I would like to know when I test a few hours after eating if a 95 is leveling off or dropping fast. Being hypounaware right out of the shoot when starting insulin makes going low a little more nerve racking.

I was thinking 20 minutes might be good too Zoe and that’s about what I did today at lunch so maybe it just wasn’t enough. Still figuring out my I:C ratio as well as the timing.

On humalog, I try to bolus 15-20 minutes ahead of time. If I am in range before the meal and get much more than 20 minutes after bolusing, then I am going to have to break out the glucose tabs because I will be low, and I will end up too high once the meal gets digested.

I wouldn't be too concerned over 170-180 @ 2 hours after eating as long as you are in range 3.5-4.5 hours later. The CGM will help immensely in this regard.

For me, I just can't imagine bolusing 30-45 minutes ahead of time, like Dave is mentioning - wow!

I don't know if this would be any help?
From what I'm told as a T2, have you got your overnight and miss a meal basal test and dose right? Or you'll be chasing your tail trying to work out your bolus.

You ask what other people do, so here is my answer:

In the morning 15-20 minutes. I set an alarm and check my bg after 15 minutes to see if it´s OK to start eating. If not, I wait another five minutes. Sometimes I need more, but thta´s the exception.

For lunch I rarly eat carbs, so if bg is in my range I injcet and then eat within five minutes.

For dinner the same. Seldom much carbs there, but if it is I apply the same 15-20 minutes rule if my bg is in range before I inject. This late in the day my experience is that 15 minutes is enough.

Another thing I do is to check my bg 1 hour after injecting. If bg is raising then I might give a second injection just to make sure the bg doesn´t raise too much. For me it´s almost impossible to get my bg down if it gets too high. The second injection is small and based on experiece and how the day has been so far.

Good luck with finding your own parameters.

Thanks for the link jack!

Looks like 15 minutes or so is the norm so that’s what I’ll be trying, setting an alarm is a good way to remember, don’t want to get distracted and forget to eat! Lunch is actually when I prefer to eat my most carbs. For now at least until I get this figured out eating a very carb dinner allows me to not have to worry about nighttime lows as much.

Yes Mike, I look forward to getting one, it would be easier and less nerve racking to up my bolus dosage if I knew the CGM would alert me to a fast downward trend since my my brain no longer does that!

I meant eating a very LOW carb dinner…

if you are eating VLC, some are you bolusing for about 50% protein? TAG total available glucose

I read some even use a regular to get the profile longer or split bolus

They even have their own group here at Tudiabetes called TAGers united

TAG = Total Available Glucose

Hmm, that idea is new for me. Yesterday I had a nice 130 when I’d normally be over 200 after lunch and I was quite pleased with myself for making progress towards better post prandials (*pats herself on the back). But an hour later I was at 180 which bummed me out. So I may have to study spliting my bolus? Which surprises me because without insulin I’m quick to go up then I fall on my own within a few hours and go hypo. I was hoping to catch the peak with my Novolog then be done with it and also not have the reactive hypos from an over worked 2nd phase that caused my hypo unawareness. Still early of course, only been doing the bolus for a few days. Truth is, I’d rather not have to split it, complicates things more:( But my goal is to get as close to normal BG as I can since I already have some signs of diabetes complications.

I tried Regular Jack and it was not good, the tail was way too long for me and caused a 38 hypo. I would consider splitting if I have to but of course would rather just have to use one shot before eating, it would be so much easier than figuring out two!

I'm T2 on oral, so you need to get someone who does it or read till you are confidant but..it seems you first bolus for your carbs and then bolus for about 1/2 the protein a 'period of time' later

google diabetic pizza effect too