Absorption of carbs from pulses

[harbottle]

I learned that Diabetes Maths was a bit woolly at the best to times a long time ago.

What I end up with is more trial-observation-repeat estimates. I rather suspect others do too.

So if repeatedly, on the printed information I would assume a rise of x given a dose of y, but each time I have *that meal* (I’m looking at you soup-and-a-slice-of-bread) the estimated x carbs and y dose repeatedly fail. So I take an additional z insulin to cover the difference. Which according to the ‘maths’ shouldn’t be needed.

It just feels like others are drawing the same conclusions from their own observations whether diet-managed or whatever. When they eat pulses they get a bigger glucose excursion than the listed info would suggest.

So they use a phrase like “I seem to be able to extract about half as many carbs again from blah than are listed” as a shorthand.

That’s my take on it anyway. 🙂

Too many variables!

I just found through months of sensor usage that the same meals didn't even give the same results on different days.

And lentils were just bizarre.

 

[beating_my_betes]

But why don't you believe that it would be possible to do this?

Because there are just too many confounding variables, most of which we can't even count never mind account for.

In a metabolic ward we can certainly get closer to some form of accuracy, but at home it would take impractical levels of controlled repetition to try and average things out.

 

[beating_my_betes]

It just feels like others are drawing the same conclusions from their own observations whether diet-managed or whatever. When they eat pulses they get a bigger glucose excursion than the listed info would suggest.

How would you draw such a conclusion?

 

[CliffH]

It's clearly stated on this forum that the members are not medical experts hence any posts they make on it shouldn't be taken as medical advice, but merely as third party comments allbeit from their own experience of the subject either generally and/or whilst they also have diabetes. Therefore if someone decides 'I'll try that!' and it doesn't work like it reportedly did for whoever, no blame can be attached to them for that.

I think this is a good point: some posts (not necessarily on this thread) do seem to stray a bit too close to giving specific medical/dietary advice, rather than simply talking about the poster's own experience.

 

[Docb]

If you approach all this from the other end......

Just suppose you ate 100g of carbohydrate and that it was all converted to glucose, that there was no mass lost, that all of the glucose was absorbed into the blood and none of it was absorbed in the body. A lot of assumptions but bear with me. This would introduce 100g of glucose into the blood stream. The molecular weight of glucose is 180 g/mol or thereabouts. This makes 100g of glucose equivalent to 0.56 mol or 560 mmol.

The human body contains about 5l of blood. So if all my assumptions were correct, 100g of carbohydrate would give a rise in blood glucose of 560/5 or about 110 mmol/l.

We all know that 100g of carbohydrate does not raise blood glucose by anything near to 100 mmol/l. Some might get a 20mmol/l or more rise and some see hardly any rise at all. Everybody else will be somewhere between those extremes.

What that means is that all my assumptions are probably wrong. It also suggests that the number seen on your meter only accounts for a fraction of the potential glucose rise from eating a couple of very large scones smothered with jam and butter.

Where all the other glucose has gone, you can speculate about for ever and not make any steps forward. Every idea has merit but working out what is what and how everything interacts will be all but impossible.

There are statistically based experimental techniques for sorting this sort of thing out - using Taguchi methods might be a place to start. Long time since I did that sort of stuff and I would not know where to start these days. May be not even possible with the human factors involved.

So keep speculating and debating about carbohydrate and glucose and have fun but don't expect to arrive at a consensus when it comes to drawing conclusions. All I ask is that you do not fall out over it. You are all equally right and equally wrong.

Good luck and I'll retire back into my bunker and do something straightforward by comparison and teach myself video and audio editing and turn myself into an internet sensation by talking absolute rubbish very convincingly on a narrow angle on some subject or other. Trickiest bit will be finding a subject, just about everything seems to have been covered......

 

[SimonP]

Because there are just too many confounding variables, most of which we can't even count never mind account for.

In a metabolic ward we can certainly get closer to some form of accuracy, but at home it would take impractical levels of controlled repetition to try and average things out.

Perhaps this is purely a case of expectation management - it depends on how accurate and over what time period you want your predictions to work. As a T1, if I can get insulin right for a meal with a given nominal(!) carb count, keep the rise lower than say 5mmol/l above current BG and be back close (to within say a couple of mmol/l) after a couple of hours (depending on the food) then that works for me - I can then correct as needed.

I'm not aiming for nor expecting to predict my BG level 10h hence down to one decimal place, but what I do want to avoid is large excursions by predicting the most likely trajectory for my BG so I can then tweak later to make up for any of the many confounding factors I didn't take into account at the start.

And there are certainly lots of confounding factors, but with time the things that generate the largest effects can be identified (carbs and their type, insulin, exercise, and stress/illness to name the ones that come to mind), at least with some degree of certainty. Enough certainty that I'm willing to take the insulin, or not and be pretty sure that it will have a similar effect to the last time, or at the very least the behaviour will be constrained into a set of BG trajectories that I can then deal with further down the line. I don't need a very long time horizon because things will change, I'll eat something, do some exercise, etc., so long term predictions aren't all that useful except overnight, which is in many ways the easiest to analyse as there are probably fewer confounding factors: probably no insulin nor food involved and it's fairly repeatable.

The good thing about the factors I listed is that they are generally fairly obvious and produce effects that are not overly transient so one has both the opportunity to know they are potentially having an effect, and to see a change in BG response over enough time to be reasonably certain that the two are correlated at least. Stress can be a tricky one mind you.

What sorts of things are you looking at on the metabolic ward and what level of accuracy are you trying to achieve assuming you're predicting something in a time-based fashion. It sounds like you're trying to achieve an accuracy which is far higher than that I want/need.

P.S. The other thing to add, which is not at all the same as developing a theory/model in any other field that I know of, is that I really don't care very much about it being general - I only care that it works for me. Once that part is working acceptably, then I might start sharing what I thinks is happening just in case it helps others with their own models. This is where couching theories in the right terms is important, the usual "but we're all different" mantra, etc.

 

[Docb]

@SimonP It has often occurred to me that looking at T1 data might be a better place to start in this sort of discussion. The wide variation carb to insulin ratios used by T1's must say something about all the other factors that have been talked about.

 

[Leadinglights]

I have been looking in my Nutritional Sciences text book and certainly the whole way in which carbohydrates are metabolised depending on the particular ratios of soluble and non soluble fibre is pretty complex and will depend on an individuals gut microbiome and enzymes present in different parts of the gut but also the overall composition of the food.
No wonder people's individual response can be very different and also not always consistent with what may be determined empirically.

 

[everydayupsanddowns]

How would you draw such a conclusion?

By repetition, observation, and trying to find patterns in the data based on my experience and understanding of how my diabetes behaves (most of the time).

If I always go to 12 with the “correct” dose for soup and a slice of bread, but only reach 9.0 as a maximum by allowing for more carbs than I “should”. Then I’ll add the extra insulin. If only to make me less grumpy about post-meal highs.

It’s how I’ve generally tried to improve my management from the beginning. Start with The Rules. Then observe, repeat, experiment, adjust, and aim for reduced glucose excursions.

 

[everydayupsanddowns]

Perhaps this is purely a case of expectation management - it depends on how accurate and over what time period you want your predictions to work. As a T1, if I can get insulin right for a meal with a given nominal(!) carb count, keep the rise lower than say 5mmol/l above current BG and be back close (to within say a couple of mmol/l) after a couple of hours (depending on the food) then that works for me - I can then correct as needed.

Yep!

 

[Satan’s little helper]

Because there are just too many confounding variables, most of which we can't even count never mind account for.

In a metabolic ward we can certainly get closer to some form of accuracy, but at home it would take impractical levels of controlled repetition to try and average things out.

The definition of madness is doing the same thing over & expecting different results? Regarding any carbs, one can go insane not only with the repetition but the different results. We test ourselves in the “wild” because none of us have time to waste living in a “controlled environment.” As I mentioned in my car analogy up stream. That’s taking positive fuel consumption averages from the manufacturer using a prototype vehicle with engineered spec on a test track at around 68mph to boast the fuel consumption.

 

[Drummer]

When I was testing every day after dinner it would be 'OK' 'right' 'yes' 'fine' 'WHAT!!'.
Every time it would be a meal with legumes of some sort which resulted in a larger than expected rise.
Once I lowered the amount of legumes, I got the expected result - when I stopped eating beans other than French and Runner my weight started to drop rapidly according to the records the clinic keep - I don't weigh myself due to all the verbal abuse I've had inflicted over the years.

 

[beating_my_betes]

@SimonP and @everydayupsanddowns

Thank you both for your considered and considerate replies. I do have more to say on the subject, but I need to get away from here for a while.

Will address this when I get back.

Cheers!