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Comment by AdamH12113 | Hacker News Reader

> Exposure to saccharin and sucralose significantly impaired glycemic response, but this was not seen with the aspartame or stevia groups. None of the blood markers show real changes in any group except for insulin levels going up in the glucose and stevia groups (and since everyone was getting glucose as part of the dosing, that suggests a lowering of the glucose-driven insulin response overall).

What does impairing glycemic response mean, exactly?

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It is your body's ability to regulate blood sugar level in presence of intakes of food or their absence.

A healthy person should have no problem maintaining blood sugar level except for very extreme situations (like running a marathon). Impaired response suggests then some kind of underlying problem.

I’m still confused. In the context of this paper, does “impaired glycemic response” mean blood sugar levels go up but do not come down because insulin production is impaired? Or that insulin levels increase and blood sugars still do not fall? Or that the glycemic response, that is the blood sugar concentrations, do not increase in the first instance?

Right, I had the same response to that sentence, see my comment infra.

It seems to me that an "impaired" glycemic response is what is actually desired, but the word "impaired" has negative connotations. It might be typical usage in a journal article, but it is not for an article in Science.

Impaired glycemic response, when bad enough, is a cause of diabetes.

Insulin is not a bad thing, high blood glucose is.

When there is no need to immediately use glucose as a fuel (like when exercising), insulin is secreted. It acts as a signal to the rest of the body to remove glucose from the bloodstream and store it (as glycogen or fat). Without insulin (and without exercise), blood glucose levels would be too high for a long time.

They mixed glucose with the artificial sweeteners so sugar level must raise. But it didn't go down, so it seems that the sweeteners could be stopping the insulin response.

Right, and that's a good thing, because lower postprandial glycemia correlates with better health outcomes: https://pubmed.ncbi.nlm.nih.gov/20234031/

I'm not sure we can equate low glycemic index foods with foods that suppress the insulin response. They might have a small insulin response in common, but their effect on blood sugar concentration is not at all the same.

I have no insight on the studio but that it's only logical "impairment" must mean the response was even less than the one expected if the same amount of glucose and no sweetener was ingested.

Otherwise it's misleading and not surprising at all.

Right, I think that's what they meant. And the result would be that your blood glucose level would spike much higher than if you had a normal insulin response. It's unclear what the health effects of that would be.

I found another paper [1] that implies that "impaired glycemic response" is measured by an "oral glucose tolerance test" and that high levels of blood glucose in the two hours after drinking a glucose solution are what they mean by an impaired response. The graphical abstract [2] from the paper discussed in the Science article has "glycemic response" graphs, which I assume are from this oral glucose tolerance test, although I wasn't able to access the paper's PDF.

[1] https://www.researchgate.net/figure/Impaired-glycemic-respon...

[2] https://www.cell.com/cell/fulltext/S0092-8674(22)00919-9?_re...

Defintion: The Glycemic Index (GI) is a measure of the extent of the change in blood glucose content (glycemic response) following consumption of digestible carbohydrate, relative to a standard such as glucose.

Blood glucose is actively regulated by your body via relying on glycogen storage and breakdown in the muscles and liver, in healthy humans this system reacts quickly to maintain a constant blood glucose level (required for say, active brain function). See figure 1 in this review (pdf) of glycogen-related inherited diseases for an overview of how it's supposed to work (it's all tied into the cellular Krebs, aka tricarboxylic acid, cycle):

https://www.researchgate.net/profile/Joseph-Wolfsdorf/public...

Practically speaking, flooding your bloodstream with sugar (soft drinks, candy) seems to overwhelm the normal functioning of that system, but when you eat more complex carbohydrates which are slowly digested (potatoes, bread, pasta, etc.) this results in a steady but slow input of sugars to the bloodstream via the digestive system, which, depending on your resting energy level, will be either stored as glycogen or fed into the Krebs cycle for cellular energy conversion.

So if glycemic response means

> change in blood glucose content (glycemic response)

then does that mean an impaired response is higher or does it mean it's lower?

If you don't know, insulin signals a process for sequestering sugars through glycogenesis.

Stevia and Glucose groups both increased plasma insulin. Contrasted with Saccharine and Sucralose which, the authors suggest, blunted insulin release and thus increased blood sugar. They cite a paper indicating that combined NNS and caloric sweeteners increase the insulin response compared with a NNS itself.

So... both..? It's a disproportion. NNS should have negligible impact on blood sugar to be called "inert", either when paired or when not, regardless of whether glucose is present or not. Addition is changing the whole formula. They're saying it's fucking up the signal interpretation. At least that's what I've put together.

Thank you. So let me see if I get it correct.

    thing         effect on plasma insulin         gut result

    glucose       baseline increase                standard

    g+sucralose   increase less than baseline      altered

    g+stevia      baseline increase                altered

    g+aspartame   baseline increase                altered

So since there was lower than baseline increase in the g+sucralose group, we can conclude that the sucralose is blunting the response that the glucose would have caused.

So, in this context, that means we got increased blood sugar because of the lower plasma insulin? Okay. I think I understand now.

one point of contention - potatoes and bread (specifically white) are some of the highest GI foods available. i specifically use these (white bread with peeled boiled potatoes) for their quick conversion to available sugars prior to exercise. some scales actually use white bread as the index point (GI = 100) because of this.

Potatoes have gotten an undeserved bad reputation. Boiled potatoes can be as 58. Especially if you cool and reheat. Mashed or fried is over 100.

Glad someone else got stuck here. I couldn't figure out from context whether this is good or bad and looking up "glycemic response" still didn't clear up whether it's a desired trait or not in terms of sweeteners, health outcomes, and diabetics for example.

Hopefully this image helps, because I am still not sure: https://ars.els-cdn.com/content/image/1-s2.0-S00928674220091...

Thanks for the image but to me personally it only raises more questions. If sucralose "impairs glycemic response", then why does the line go up more aggressive on the "glycemic response" chart? Is having a higher response bad? Do I want my body's glycemic response to be as inert as possible?

I was confused by that too.

are saccharin and sucralose good (benign) sweeteners?

or is stevia a good (benign) sweetener?

"good (benign)"

More accurate word choice would be "less bad".

I don't believe dietary science knows of a benign sweetener at this time.

Kind of like the situation with alcohol; there's some that are worse than others, none that are beneficial, none that are neutral.

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