Sugar is increasingly criticized. However, it is often overlooked that different types of sugar can differ significantly in their digestion and their impact on blood sugar levels.
An interesting example is Isomaltulose. While this carbohydrate, like household sugar, provides energy, it is broken down much more slowly by the body. As a result, blood sugar levels rise less quickly and less sharply after consumption.
Current studies also show that isomaltulose may also influence the release of certain gut hormones, making it an exciting carbohydrate for modern nutritional concepts.
What is Isomaltulose?
Isomaltulose is a disaccharide consisting of the two monosaccharides glucose and fructose. Thus, it essentially has the same building blocks as common household sugar, also known as sucrose.
The crucial difference lies in the bond between these two sugar building blocks. In isomaltulose, this bond is more stable and is broken down more slowly by digestive enzymes.
This means:
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The carbohydrates contained enter the blood more slowly.
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The blood sugar rise is flatter.
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The energy from the carbohydrates is provided over a longer period.
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Strong short-term blood sugar spikes can be reduced compared to household sugar.
Isomaltulose is usually produced by enzymatic conversion of sugar. Flavor-wise, it resembles conventional sugar but has a milder sweetness.
Slower Digestion Instead of a Quick Sugar Spike
In household sugar, glucose and fructose are separated and absorbed relatively quickly. This can cause blood sugar levels to rise significantly within a short period.
Isomaltulose, on the other hand, is broken down more slowly. Glucose enters the bloodstream over a longer period, resulting in a more even blood sugar concentration.
A systematic review of available studies concluded that isomaltulose causes a lower blood sugar increase compared to sucrose, especially in the early phase after consumption. The results also indicate a flatter and more sustained blood sugar curve and a lower insulin response.
This difference is also regulatorily recognized: In the European Union, a health claim is permitted stating that foods or beverages with isomaltulose instead of sugar cause a lower blood glucose rise after consumption. The prerequisite is that the respective conditions for using the claim are met.
What do GLP-1 and PYY have to do with it?
Particularly interesting is the influence of isomaltulose on certain hormones released in the gut after eating.
These include:
GLP-1 – Glucagon-like Peptide-1
GLP-1 is an endogenous gut hormone involved in regulating blood sugar and insulin secretion.
PYY – Peptide YY
PYY is also produced in the gut and is involved, among other things, in the communication between the digestive system and the brain.
Since isomaltulose is digested more slowly, larger amounts of carbohydrates reach lower parts of the small intestine. There, especially many cells release GLP-1 and PYY.
The effect occurs through normal physiological digestive processes. Isomaltulose is therefore in no way comparable to drugs that specifically act on GLP-1 receptors.
New study investigates the so-called "second-meal effect"
A study published in Nutrients in 2025 investigated 15 older adults with metabolic syndrome. The study was randomized, double-blind, and designed in a crossover fashion.
Participants received on different test days either:
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50 grams of isomaltulose or
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50 grams of sucrose
The sugars were added to a beverage and administered at different times before a standardized meal.
After isomaltulose, a slower and lower blood sugar rise was observed than after sucrose. At the same time, higher and longer-lasting concentrations of the gut hormones GLP-1 and PYY were measured.
Interestingly, isomaltulose not only affected the immediate response after the drink. The blood sugar response to the subsequent meal was also more favorable. Scientists refer to this as the second-meal effect.
The study, with 15 participants, was small and examined short-term metabolic reactions. Nevertheless, it provides interesting indications that the choice of carbohydrate source may also influence the response to a later meal.
Earlier study shows comparable results
Already in 2016, the German Institute of Human Nutrition investigated ten adults with type 2 diabetes. Here, too, 50 grams of isomaltulose and 50 grams of household sugar were compared.
After consuming isomaltulose, the maximum blood glucose concentration was on average about 20 percent lower. The measured insulin secretion was even about 55 percent lower than the response to household sugar.
At the same time, the GLP-1 concentration rose faster and remained elevated longer. Researchers also explained these differences by the slower breakdown and absorption of isomaltulose in the small intestine.
For which products is isomaltulose suitable?
Isomaltulose can be interesting wherever carbohydrates or sweetness are desired, but strong blood sugar spikes should be avoided.
Possible applications include:
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Beverage powders
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Sports drinks
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Mueslis and breakfast products
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Protein and energy bars
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Baked goods
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Meal replacement products
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Carbohydrate mixtures for longer physical exertion
Since isomaltulose is completely digested and utilized, it is particularly suitable for products that are intended to provide energy from carbohydrates. It is not a sugar alcohol and is therefore metabolized differently than, for example, erythritol or xylitol.
Is isomaltulose sugar-free?
No. Isomaltulose remains a sugar and provides approximately four kilocalories per gram – about the same amount of energy as household sugar.
Its advantage is not being calorie-free. The crucial difference lies in its slower digestion and the resulting flatter blood sugar curve.
Isomaltulose should therefore not be understood as a free pass for unlimited sugar consumption. However, it can be a sensible alternative if sugar or rapidly available carbohydrates are to be specifically replaced.
Conclusion: A smarter choice for carbohydrates
Isomaltulose shows that not all sugar is the same. Although it consists of the same basic building blocks as household sugar, the special chemical bond changes the speed of digestion.
Studies consistently show a slower and lower blood sugar rise compared to sucrose. Newer studies also provide interesting indications of a longer-lasting release of the gut hormones GLP-1 and PYY, as well as a more favorable blood sugar curve after a subsequent meal.
Isomaltulose is therefore not a calorie-free sugar substitute, but a slowly available carbohydrate with special metabolic properties. For well-thought-out foods, sports products, and nutritional concepts, it can be an interesting and scientifically well-studied alternative to conventional sugar.
