What's the maximum a post-prandial rise should reach?

Most/all commentators talk about pre-prandial levels and levels 2 hours after eating, but what about the initial rise? Is there a maximum that's regarded as healthy/normal?

I also get the situation where a food (eg porridge) generates a sharp peak, going high but recovering to pre-prandial level quickly, whilst another (yoghurt then toast and butter) doesn't go anywhere near as high, but stays elevated 2mmol/L higher than pre-prandial level at the 2 hour mark, descending at 3h.. Are both to be avoided, or one or both ok? (Found eating same toast with 2 boiled eggs hardly blipped relatively!).

JAT1 said:

How high do the peaks go? Knowing what your blood readings are and how long after eating you measured them would help with providing an opinion. Some meals also get absorbed faster than others. I personally try to never peak higher than 10 mmol.

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The highest are between 10 and 11.
Pretty much all those peak at c1hr on CGM and are back down by 2 hrs, often after reactive dip, The lower ones only reach 9-10, sometimes lower, but stay elevated for 3+ hours sometimes.
I know these levels are not high for some, but trying to keep it that way or better since hitting pre-diabetic numbers - most recently at 42 from bloods last Monday (so slightly down).

catinahat said:

Our meals vary rarely contain just one element, so when trying to understand post prandial numbers you need to take into consideration how the various macronutrients affect each other.
Your porridge is mainly carbs and not much of anything else, so the carbs get digested, blood sugar goes up, insulin brings it down.
Whereas your yoghurt toast and butter probably has less carbs than the porridge but it also has lots of fat in the yoghurt and the butter. Fat slows down the digestion of the carbs so the carbs in your toast take longer to show up in your blood.
Personally I wouldn't be happy with levels around 10 at any time. I aim to keep my blood sugar below 8.5, if I had something that sent me up to 10, I wouldn't be having it again or I would have less of it next time, unless of course it's something I enjoy as a very occasional treat.

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Thank you for all that. I appreciated that the fat was slowing down digestion, whereas porridge didn't have anything to 'dilute' it. My interest/concern was that taking the usual advice on board, the former is theoretically as bad/worse than the latter, as my 2hr testing shows blood sugar higher in the former case than the latter, where it's back to normal.
Ironically, my highest levels have been when racing (orienteering), higher than any food so far. In the past, I've used porridge only as a pre-race food, a low carb background proving not great if racing for more than 40 mins. Trying to work out the balance and now I know the level of rise not sure whether worth it, and perhaps need to seek alternative.

catinahat said:

Perhaps you should look into fueling your exercise with fat rather than carbs, I don't claim any first-hand knowledge of it, my exercise walks barely reach snails pace nowadays.
But I have read accounts of people who successfully compete in various sports without carbing up first.
You might find these interesting
https://www.athleticmentors.com/what-being-a-fat-adapted-athlete-really-means/
https://www.marksdailyapple.com/how-using-fat-for-fuel-can-boost-athletic-performance/

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Interesting point. I've done a lot of work on that over the past 5 years. Whilst that's fine for relatively slow, long distance, continual expenditure (it's great for audax cycling for instance), or for short high intensity (for me, I find I can sustain for anything up to around 40 mins), and I train for most of my time sticking to low carb higher fat, for high intensity (racing) longer distances it just can't generate the energy needed (especially given the strength requirements of orienteering). More and more athletes are going over to precision use of carbs within a low carb framework (fat adaptation still makes a very useful difference, in making the body far more efficient and less carb reliant) - the second of those two articles you link to refers to that. Racing, as I do, at up to 80 mins high intensity in terrain, carbs remain important (and I now eat such on the run from 40 mins onwards). Any sugar generated gets used up instantly! (I should make clear that most of the time I'm on a low carb diet- it's just while I've had this CGM for this fortnight, I've been trying out various foods and combinations to see what works for me).

I meant to ask in my last post - any specific reason why you use 8.5 as a top end level? That's part of what I'm trying to explore, so any info gratefully received.