Some of them do and some of them barely register, and the difference between the two ends is large enough that treating "sugar alcohols" as one ingredient is the actual mistake. In the international glycemic index tables kept by the University of Sydney, erythritol sits at essentially zero. Maltitol is a different animal. It is what most sugar-free chocolate is built on, and published figures put it somewhere between the mid thirties and around fifty depending on the form and the study, against table sugar at about 65. Those two are grouped under one line on the label anyway.
That grouping is the practical problem, because the "net carbs" number on the front of a bag is usually calculated by subtracting every gram of sugar alcohol as though all of it were erythritol. Our post on how to read a sugar-free label works through the panel line by line. This one is about what the numbers actually mean once you have found them.
One thing said plainly before anything else: this is a recipe site, not a clinic. I can tell you what is in a food and what the published research describes in general terms. I cannot tell you what any of it will do to you, and if you are managing blood sugar under a diagnosis, your doctor knows your numbers and your medications and I do not. Take this as background for a conversation with them, not a substitute for one.
Why they are not interchangeable
Sugar alcohols, or polyols, are sugars that have been chemically reduced. What separates them from each other is almost entirely how much of each one your small intestine absorbs, and what happens to the part that is absorbed.
Erythritol is a small molecule and most of it, on the order of ninety percent, is taken up in the small intestine. Once absorbed, your body has no efficient pathway to break it down for energy, so it passes through the kidneys and leaves in urine largely intact. It arrives, does nothing, and goes. That is why its glycemic index measures at or near zero and why studies looking at insulin response to it generally find no meaningful rise.
Xylitol is absorbed more slowly and incompletely, and the portion that does get through is metabolized. Published glycemic index values sit in the range of roughly 7 to 13. Small, real, not zero.
Sorbitol lands in the same neighbourhood, usually reported around 9, and it is absorbed poorly enough that the digestive complaints land harder.
Maltitol is the outlier and the reason this post exists. It is a disaccharide, made from maltose, and a meaningful fraction of it is broken down and absorbed as glucose. Reported glycemic index values cluster somewhere between the mid thirties and around fifty, with maltitol syrup generally testing higher than the powdered form. Call it roughly half to two thirds of the response you would get from sugar. For a product marketed as sugar-free, that is a lot.
Isomalt sits low, usually reported in single digits, and shows up mostly in hard candy and commercial coatings.
If you have ever eaten a sugar-free candy bar and felt exactly the way a normal candy bar makes you feel, maltitol is the likeliest explanation and it is worth checking the ingredient list rather than assuming you imagined it.
Where allulose sits, and why it is a different question
Allulose is not a polyol at all. It is a rare sugar, an actual monosaccharide, and it ends up in the sugar-free aisle by function rather than by chemistry. We wrote a whole post on why allulose is not a sugar alcohol because the distinction matters most to people who have written off the entire category over one bad digestive experience.
For blood sugar purposes: allulose is absorbed but not metabolized for energy, and it leaves in urine much the way erythritol does, so it also tests at or near zero on glycemic index. A handful of small human trials have reported that allulose modestly lowers the glucose response to carbohydrate eaten alongside it. Those trials are small and short, the effect has not been pinned down at any scale worth acting on, and presenting it as settled would be dishonest. Treat it as an interesting possibility rather than a reason to pick one sweetener over another.
The net carb maths, and where it breaks
"Net carbs" is not a term the FDA defines. It has no legal meaning on a US label. What manufacturers do is take total carbohydrate, subtract fibre, subtract all of the sugar alcohols, and print the remainder on the front of the package in large type.
Subtracting erythritol at one hundred percent is defensible, because roughly none of it reaches your bloodstream as usable carbohydrate. Subtracting maltitol at one hundred percent is not, because a real share of it does. A bar containing 20 grams of maltitol and advertising 2 net carbs is describing an ingredient that behaves partly like sugar as though it behaves like nothing at all.
The correction is not complicated. Find the "Sugar Alcohol" line on the back of the panel, then find which polyol it is in the ingredient list. If it says erythritol, the front-of-pack number is roughly honest. If it says maltitol or maltitol syrup, assume something in the region of half of those grams behave like carbohydrate and judge the product on that. If it lists several, you cannot tell the split from the label and you are guessing.
Sorbitol, mannitol and xylitol sit between those two poles, closer to the erythritol end, and the same instinct applies: identify the actual molecule before you trust the arithmetic done on top of it.
What a glycemic index number can and cannot tell you
This is the part most articles skip, and skipping it is how a reasonable number becomes a bad decision.
Glycemic index is measured under specific conditions: a fixed 50 gram carbohydrate load, given to fasted volunteers, with blood glucose tracked for two hours and averaged across a small group. It is a property of a carbohydrate measured in isolation. It is not a property of a dessert.
Three things follow from that. A portion of dessert rarely contains 50 grams of anything, so glycemic load, which accounts for the actual amount you eat, tells you more than the index does. Whatever the food is eaten with changes the response substantially, since fat, protein and fibre all slow gastric emptying. And individual variation is genuinely large. A 2015 Weizmann Institute study published in Cell put continuous glucose monitors on 800 people and found that two of them eating an identical meal can post very different curves. That is the honest reason nobody can hand you a number that applies to you specifically.
So the useful way to read the figures above is as a ranking rather than a prediction. Erythritol and allulose belong at the bottom. Maltitol belongs well up the list, closer to sugar than the marketing suggests. Where your own line lands is something you would find out with a meter and a conversation with your doctor, not from a table.
What this means when you are actually baking
The gap between erythritol and maltitol mostly matters when you are buying something. When you are making it, you control the sweetener and the problem largely goes away, because maltitol is almost entirely a commercial ingredient. It shows up in sugar-free chocolate bars, coated candy and cheap baking chips because it behaves like sugar in a factory, and it is uncommon in a home pantry.
That is worth knowing before you buy a bag of sugar-free chocolate chips to put into an otherwise careful recipe, since the chips can quietly account for most of the carbohydrate in the finished thing. Read that bag the same way you would read a candy bar.
Two related pieces if you want the rest of the picture. Our honest read on whether erythritol is bad for you covers the 2023 cardiovascular research, which is a separate question from this one and is genuinely unresolved rather than settled in either direction. And our guide to which sweetener suits which job is the one to read if you are choosing what to keep in the cupboard.
If you would rather sidestep sweeteners altogether for a while, plenty of desserts get there on fruit and dairy, and our no added sugar roundup collects twenty of them with the real macros on each. There is a free sampler at the bottom of this page if you want a handful to start with.
