T1,3,LADA: Using some form of CGM, when do your BSLs peak after a meal

[kitedoc]

In another thread the timing and utility of single point gluco-meter readings was discussed.
So I wondered what your actual measured peak times (or range of times) for BSLs is
after meals (post-prandial) with use of CGMs? (Libre, or other??

 

[kitedoc]

Hi @Mel dCP, @Knikki, @helensaramay, @Scott-C , @evilclive, @therower, @Cobia, @Chowie, @tim2000s and others.
Any data please ??

 

[LooperCat]

Unless I’ve really messed up my carb counting, which tends to happen when I eat out and possibly have unknown sugar in my meal, my CGM line stays pretty flat. If there’s sugar in my food, it’ll start to climb rapidly within half an hour. If it’s just an underestimation of carbs, I’ll see a rise after about 90 minutes. I sometimes see a protein rise after four hours.

For clarification I eat very low carb (<30g daily) and don’t prebolus. I dose Novorapid when I sit down to eat.

 

[Bluetit1802]

I'm T2 and not on any medication.
I do use the Libre.
My peaks are always between an hour and 90 minutes. By 2 hours the peak is well down and I don't get any subsequent ones.

 

[Cobia]

@Mel dCP i cant see you messing up carb counting.....

@kitedoc ... just from what i see.... a hit of sugar or glucose tab.... starts about 15-20 min peak guess hour. carbs start about 30 min peaks roughly1.5-2 hours depending on what they are.

Protein usally starts 60-90 min peaks 4-5 hours usally out lives the bolus.... was keeping in range till i started the gym im still tweaking it but tonight is the first time i havnt had to look for glucose tabs for me strawberry creams .... you know why im there its changing the rules again....

Will message the graph to you for today.

 

[therower]

Hi @kitedoc . As you are aware so much depends on food eaten, time of day, pre bolus and physical or mental exertion.
I use a Dexcom G4 and as a general rule of thumb with no extreme mitigating factors I will generally see a rise for around an hour and half, then usually level off for an hour or so, followed by a steady downward trend.
Doesn’t always work out this way but that’s the joy of diabetes I guess

 

[Scott-C]

Hi, @kitedoc , Dana Lewis, one of the pioneers of homemade artificial pancreas, wrote an interesting article on calculating carb absorption rates:

https://diyps.org/2014/05/29/determining-your-carbohydrate-absorption-rate-diyps-lessons-learned/

With me, peaks can be very variable. I'll usually see a rise start after about 30 to 45 mins, peaking about 60 to 90 mins later, but with some low gi foods, I can have a straight line for like a whole 3 hrs then it starts to rise from then. But other times the same meal just doesn't do that.

With cgm, I'm able to watch it and usually pin it with a few units correction before it gets too high, but sometimes it just does a flier and needs way more.

I'm suspecting one cause might be that if it's a particularly low gi meal, the digestion of the food is still kicking in well after the insulin has peaked.

Another possibility I've wondered about is that, while, after 30 yrs of T1, I have no obvious complications apart from mild background retinopathy, I wonder sometimes whether there is some mild vagus nerve damage, which can slow the empyting of the stomach into the intestine where glucose is absorbed. I've more or less ruled this out as I don't seem to have any of the other symptoms of gastroparesis, and it only happens once in a while.

I've been re-reading Stephen Ponder's Sugar Surfing recently. He says that during it's travels round the body after injection, some insulin is destroyed before it gets anywhere near doing its job, and the amount destroyed can, astonishingly, be as high as 90% depending on how one's biology is working that day.

He doesn't cite any references for that but if that is correct, it would go a long way to explaining T1 randomness - how 5u will be very effective one day, and seemingly do nothing the next.

I think what cgm.brings to the game is a heightened awareness of the user's general insulin sensitivity over the last few days; a keener appreciation of how 2 or 5 or 7 units might act that particular day; information on whether we're trending up or down or stable pre-meal so we can decide on adding or subtracting from the bolus; and accumulated info from long use of it to be clearer about appropriate pre-bolus timing for different types of meal.

Stitch all those factors together, and we can end up pushing lines which don't really have any post-prandial peak at all:

But, of course, T1 being T1, you then get rubbish like this, flat line for 2hrs post-meal, then an inexplicable rise to 9 which took 7u to drag down. I reckon there's something in what Ponder says - some days more insulin is being destroyed than on other days. I'm fairly relaxed about this sort of stuff now - it's T1, it happens, heck, it would be boring if it was too easy!

 

[kitedoc]

Unless I’ve really messed up my carb counting, which tends to happen when I eat out and possibly have unknown sugar in my meal, my CGM line stays pretty flat. If there’s sugar in my food, it’ll start to climb rapidly within half an hour. If it’s just an underestimation of carbs, I’ll see a rise after about 90 minutes. I sometimes see a protein rise after four hours.

For clarification I eat very low carb (<30g daily) and don’t prebolus. I dose Novorapid when I sit down to eat.

Thank you @Mel dCP, do you ever do an extended bolus to cater for say, a higher usual meal with protein like white fish?

 

[kitedoc]

Hi @kitedoc . As you are aware so much depends on food eaten, time of day, pre bolus and physical or mental exertion.
I use a Dexcom G4 and as a general rule of thumb with no extreme mitigating factors I will generally see a rise for around an hour and half, then usually level off for an hour or so, followed by a steady downward trend.
Doesn’t always work out this way but that’s the joy of diabetes I guess

Thank you @therower. Trying to match BSL curves and insulin curves is so tricky. Even with a pump, despite having a programmed basal to deal with things like DP, the bolus doses still needs juggling I find.
I am currently trying out the extended bolus function: say 40% Novorapid at meal time for any carbs and 60% after say 45 to 60 minutes to catch the protein -> glucose surge later !!

 

[kitedoc]

Hi, @kitedoc , Dana Lewis, one of the pioneers of homemade artificial pancreas, wrote an interesting article on calculating carb absorption rates:

https://diyps.org/2014/05/29/determining-your-carbohydrate-absorption-rate-diyps-lessons-learned/

With me, peaks can be very variable. I'll usually see a rise start after about 30 to 45 mins, peaking about 60 to 90 mins later, but with some low gi foods, I can have a straight line for like a whole 3 hrs then it starts to rise from then. But other times the same meal just doesn't do that.

With cgm, I'm able to watch it and usually pin it with a few units correction before it gets too high, but sometimes it just does a flier and needs way more.

I'm suspecting one cause might be that if it's a particularly low gi meal, the digestion of the food is still kicking in well after the insulin has peaked.

Another possibility I've wondered about is that, while, after 30 yrs of T1, I have no obvious complications apart from mild background retinopathy, I wonder sometimes whether there is some mild vagus nerve damage, which can slow the empyting of the stomach into the intestine where glucose is absorbed. I've more or less ruled this out as I don't seem to have any of the other symptoms of gastroparesis, and it only happens once in a while.

I've been re-reading Stephen Ponder's Sugar Surfing recently. He says that during it's travels round the body after injection, some insulin is destroyed before it gets anywhere near doing its job, and the amount destroyed can, astonishingly, be as high as 90% depending on how one's biology is working that day.

He doesn't cite any references for that but if that is correct, it would go a long way to explaining T1 randomness - how 5u will be very effective one day, and seemingly do nothing the next.

I think what cgm.brings to the game is a heightened awareness of the user's general insulin sensitivity over the last few days; a keener appreciation of how 2 or 5 or 7 units might act that particular day; information on whether we're trending up or down or stable pre-meal so we can decide on adding or subtracting from the bolus; and accumulated info from long use of it to be clearer about appropriate pre-bolus timing for different types of meal.

Stitch all those factors together, and we can end up pushing lines which don't really have any post-prandial peak at all:

View attachment 32333

But, of course, T1 being T1, you then get rubbish like this, flat line for 2hrs post-meal, then an inexplicable rise to 9 which took 7u to drag down. I reckon there's something in what Ponder says - some days more insulin is being destroyed than on other days. I'm fairly relaxed about this sort of stuff now - it's T1, it happens, heck, it would be boring if it was too easy!

View attachment 32334

Thank you @Scott-C ! Your graphs show the value of CGM !! Not sure what might be destroying insulin more quickly on one day than another. But some stress leading to increased adrenaline and cortisone one day seems to knock the effectiveness out of the insulin that day !!
I found two articles (scientific jargon +++): https:doi.org/10.1210edrv.19.5.0349 and https:doi.org/10.2337/diaspect.17.3.183
the first stated that because we inject insulin the liver does not destroyed as much of it as when a non-diabetic's insulin 'hits' the liver very soon after it is released from the pancreas gland. But our kidneys do more of the destruction of it.
The other points out that diabetes type one is a two-hormone disorder: not enough insulin and too much glucagon.
As I have posted to @therower, I am experimenting with taking part of the bolus insulin (say 40%) with the meal and the rest 45 to 60 minutes later (courtesy of the pump) to see if I can catch both carb-related BSL rise and later protein-> glucose surge.
A CGM would help heaps. Waiting on the finances to go for Dexcom !!

 

[Cobia]

A CGM would help heaps. Waiting on the finances to go for Dexcom !!

Things to think about.


With the dexcom you can get transmitters rebatteried to make it more afordable. Catch is you will need an android phone and xdrip+ .....

This is the way im going if i go the pump route.....

 

[kitedoc]

Thanks @Cobia. For me with the Tandem Slim x 2 pump I could use Dexcom with that,
not sure when G5 will be here and linkable.
And finances will need to align with the universe first (oh, and the missus) !!!!

 

[therower]

Hi @kitedoc . Good luck with your experimenting. I’m still on mdi which by all accounts is more difficult than all these new pumps. But on saying that the Dexcom is a brilliant piece of kit in helping to keeps BSL within a certain range.
Extra chores around the house might swing it with the good lady.
Selling some of those wonderful kites would surely re align the finance planets.

 

[LooperCat]

Thank you @Mel dCP, do you ever do an extended bolus to cater for say, a higher usual meal with protein like white fish?

Always. I dose with my food for the carbs as I sit down to eat and add a dose over four hours to cover the protein. My ratio is 1:10 for carbs and 1:20 for protein.

 

[kitedoc]

Always. I dose with my food for the carbs as I sit down to eat and add a dose over four hours to cover the protein. My ratio is 1:10 for carbs and 1:20 for protein.

Hi @Mel dCP, How does the dose extended over 4 hours work?
Is it like adding to the basal dose for those 4 hours or some other technique or mode on the Omnipod??

 

[kitedoc]

Thanks @therower for the information.
Pumps and mdi each have pluses and minuses - as long as you can get the best out of tweaking either
what else can you do ??
My nurse tells me the most stable T1Ds are those who tend to be restricted to a wheelchair - less things to happen
and thus go wrong. I am glad there is an up side at least for them.
The Kite Festival is next week at Easter and I tend to buy more than I could ever sell but
there is also the wisdom of saving up the pennies instead !!
See my post in D 'R' Us for a laugh !!

 

[LooperCat]

Hi @Mel dCP, How does the dose extended over 4 hours work?
Is it like adding to the basal dose for those 4 hours or some other technique or mode on the Omnipod??

I could do a combined dose with a bit up front and the rest spread over the four hours but I find it easier to do the carbs dose in one hit and then a second extended one. Two stages makes it easier to log in my other apps.

 

[evilclive]

'Fraid I've got nothing really for this - it varies too much. If' I've got it right there's not much of a lump, if I've got it fairly wrong there could be a really big lump for a long time.