Trehalose is a carbohydrate made from two glucose molecules joined together.

Like other digestible carbohydrates, it ultimately provides glucose to the body. Indeed, foods containing trehalose in Great Britain are specifically required to state that “Trehalose is a source of glucose.”[1]

What makes trehalose interesting is how that glucose becomes available.

Before trehalose can be absorbed, an enzyme called trehalase must split the molecule into its two constituent glucose molecules. Human studies show that this produces a markedly different blood-glucose and insulin response from consuming the same quantity of glucose directly.[2]

The result is one of the most interesting properties of trehalose:

Trehalose provides glucose, but human studies show a substantially gentler post-meal glucose and insulin response than equivalent amounts of free glucose.

What happens after eating Trehalose?

Free glucose requires very little digestion before it can enter the bloodstream.

Trehalose first has to be broken down by trehalase in the small intestine.[2]

That additional digestive step changes the shape of the response.

Rather than the rapid rise produced by free glucose, research consistently shows a slower and lower increase in circulating glucose, accompanied by a smaller insulin response.[2][3][4][5]

This does not mean trehalose contains no glucose.

It means that the glucose arrives differently.

The 25g Trehalose versus glucose study

One of the clearest human studies compared 25g of trehalose with 25g of glucose in 20 healthy adults using a crossover design.[2]

The differences were substantial.

Blood glucose and insulin were significantly lower during the first hour following trehalose than following glucose.[2]

Perhaps the most striking results were the total two-hour responses:

The blood-glucose response to trehalose averaged just 38% of that produced by glucose.

And:

The insulin response averaged 36% of that produced by glucose.[2]

Those figures provide a useful explanation for much of the interest in trehalose as an alternative carbohydrate.

Where does the often-quoted “GI 38” come from?

A glycaemic index figure of around 38 is frequently associated with trehalose.

This can be traced, at least in part, to the 25g crossover study above.

Researchers calculated each participant's two-hour glucose response to trehalose relative to glucose. The average was:

38%

and the authors noted that this ratio was equivalent in concept to the calculation used for glycaemic index.[2]

There is, however, an important distinction between reporting that result and presenting GI 38 as a universally established value.

A conventional GI test usually uses a larger available-carbohydrate load and a standardised testing protocol. The trehalose researchers deliberately used 25g rather than the usual 50g because of gastrointestinal tolerance considerations.[2]

So the strongest way to describe the finding is:

In a controlled human study, 25g of trehalose produced 38% of the two-hour blood-glucose response produced by the same quantity of glucose.

That gives customers the useful information without creating false precision around a single universal GI number.

The insulin response was even more striking

Blood glucose is only part of the story.

Insulin is released in response to rising blood glucose and helps move glucose from the bloodstream into tissues.

In the same 25g experiment:

glucose produced a peak insulin concentration of 38.1 µIU/mL

whereas:

trehalose produced a peak of only 15.5 µIU/mL.[2]

The total two-hour insulin response following trehalose was around:

36% of the response to glucose.[2]

The study also measured the gut hormone GIP, which stimulates insulin secretion following carbohydrate consumption.

Trehalose produced a much smaller GIP response than glucose.[2]

This supports the overall picture of slower carbohydrate processing and a less abrupt metabolic response.

Larger Trehalose doses show the same pattern

The difference is not confined to the 25g study.

A randomized, double-blind crossover trial studied 21 obese men consuming beverages containing 75g of carbohydrate.[3]

Compared with glucose, beverages containing trehalose produced:

20–35% lower overall glucose and insulin responses.[3]

That is important because the dose was substantially larger than the 25g used in the Japanese crossover experiment.

Despite differences in population and study design, the direction of the result remained the same:

trehalose produced a lower glycaemic and insulinaemic response than glucose.

What happens when Trehalose is consumed with food?

People rarely consume carbohydrate dissolved in water in isolation.

A Maastricht University study therefore examined trehalose in overweight adults both:

• as a carbohydrate drink
• and as part of a mixed meal.[4]

Trehalose again produced a lower peak glucose response than glucose.

Insulin peaks and total insulin response were also reduced.[4]

This is commercially relevant because it demonstrates that the distinctive behaviour of trehalose is not confined to an artificial fasting glucose test.

It was also apparent when carbohydrate was consumed as part of an ordinary mixed meal.

Research in people with impaired glucose tolerance

Researchers subsequently repeated similar work in people with impaired glucose tolerance.[5]

Once again, replacing rapidly absorbed glucose with trehalose produced lower post-meal glucose and insulin responses.[5]

Taken together, these acute human studies present a remarkably consistent picture:

Trehalose is digested to glucose, but produces a slower and less pronounced rise in blood glucose and insulin than free glucose.

That is the central finding from the human evidence.

Why is Trehalose different from ordinary glucose?

The difference starts with its structure.

Trehalose consists of:

glucose + glucose

linked by an unusual α,α-1,1 bond.

The molecule therefore cannot simply enter the bloodstream intact as glucose.

Trehalase must first break that bond.[2]

The sequence is:

Trehalose → trehalase digestion → two glucose molecules → absorption

Compare this with consuming glucose directly:

Glucose → absorption

That helps explain why TREHA® can still function as a carbohydrate while producing a more gradual post-meal response.

Trehalose is not a zero-carbohydrate sweetener

This distinction is important.

TREHA® is not comparable with an intense non-caloric sweetener.

It is a digestible carbohydrate and a source of glucose.[1]

Its interest comes from combining several unusual properties:

• about 40% of the sweetness of sucrose
• useful physical properties as a sugar
• two glucose molecules per trehalose molecule
• slower intestinal digestion than free glucose
• a smaller acute glucose and insulin response than equivalent glucose loads.[2][3][4][5]

That is quite a different proposition from simply removing carbohydrate altogether.

What about ordinary table sugar?

Sucrose and trehalose are both disaccharides, but their structures are different.

Sucrose contains:

glucose + fructose

whereas trehalose contains:

glucose + glucose

joined through its characteristic α,α-1,1 linkage.

This means they are digested by different enzymes and do not produce identical metabolic profiles.

It also helps explain why reducing sweetness with TREHA® does not require moving to a non-sugar sweetener.

TREHA® remains a functional sugar ingredient.

What happens with regular Trehalose consumption?

Researchers have also investigated whether the distinctive acute response translates into measurable effects with regular consumption.

One double-blind trial enrolled 34 adults with BMI of at least 23 and compared:

10g trehalose per day

with:

10g sucrose per day

for 12 weeks.[6]

After 12 weeks, the trehalose group showed a significant reduction from baseline in blood glucose measured two hours after an oral glucose-tolerance test.[6]

Among participants with relatively high levels of trunk fat, changes in several measurements including waist circumference and systolic blood pressure also favoured trehalose over sucrose.[6]

This extended the research beyond single-meal glucose testing.

What about smaller daily amounts?

A later double-blind randomized trial studied 50 healthy adults consuming either:

3.3g trehalose per day

or:

3.3g sucrose per day

for 78 days.[7]

Overall changes in body composition and routine blood measurements were similar between the groups.

However, among participants who began the study with relatively high post-meal glucose, the two-hour glucose concentration after an oral glucose challenge was significantly lower in the trehalose group than in the sucrose group.[7]

The research therefore suggests that the most interesting longer-term effects may be seen particularly in people whose glucose handling is already towards the higher end of the normal range.

What does research in people with type 2 diabetes show?

A 2023 randomized controlled pilot trial studied 40 adults with type 2 diabetes consuming 3.3g trehalose or sucrose daily for 12 weeks.[8]

The trial found a significant reduction in C-reactive protein, an inflammatory marker, in the trehalose group compared with sucrose.[8]

However, fasting glucose, HbA1c, insulin and measured insulin resistance did not significantly differ between groups.[8]

This is useful context for understanding what the research does and does not establish.

The strongest human evidence for TREHA® remains its distinctive acute glucose and insulin response, rather than positioning it as a treatment for diabetes.

So does Trehalose cause a blood-sugar spike?

Trehalose certainly raises blood glucose because it is ultimately digested into glucose.[1][2]

But the human studies demonstrate that the shape of the response is very different from consuming free glucose.

Compared with equivalent glucose loads, TREHA® has repeatedly produced:

• a lower early glucose peak
• lower total post-meal glucose exposure
• a smaller insulin peak
• lower total insulin response.[2][3][4][5]

So a more useful way of thinking about TREHA® is:

a glucose-providing carbohydrate with a more gradual post-meal profile than free glucose.

Why might that matter in food formulation?

This is where the research becomes particularly interesting for food developers.

Many food products require sugar for more than sweetness.

Sugar contributes to:

• texture
• solids
• moisture
• freezing behaviour
• structure
• shelf quality

Simply removing sugar can therefore compromise the food.

TREHA® offers another option.

It allows manufacturers and chefs to retain the useful functional characteristics of a real sugar while also providing:

• substantially lower sweetness
• a distinctive glucose-release profile
• lower acute glucose and insulin responses than free glucose.[2][3][4][5]

That combination explains why trehalose attracts interest not only in baking and frozen-food development, but also in sports nutrition and carbohydrate formulation.

Is Trehalose a “low-GI sugar”?

You will often see trehalose described this way online.

There is legitimate science behind that description: the controlled 25g human trial produced a trehalose-to-glucose response ratio of 38%.[2]

However, published GI values for trehalose are not completely uniform, and the 38% experiment did not use the standard 50g carbohydrate load normally associated with formal GI testing.

For Trehalose UK, we therefore prefer the more informative statement:

Human studies consistently show that trehalose produces a lower and more gradual blood-glucose and insulin response than an equivalent quantity of free glucose.

And where a numerical comparison is useful:

In one controlled human crossover study, 25g trehalose produced 38% of the two-hour glucose response and 36% of the insulin response produced by 25g glucose.[2]

Those are directly measured human results.

What the research tells us

The human evidence allows several clear conclusions.

TREHA® is a source of glucose

The body ultimately digests trehalose into two glucose molecules.[1][2]

It is processed differently from free glucose

Trehalase must first hydrolyse the molecule before the resulting glucose is absorbed.[2]

Acute blood-glucose responses are substantially lower than with glucose

This finding has been reproduced in healthy, overweight and metabolically impaired participants.[2][3][4][5]

Insulin responses are also lower

The difference has been demonstrated repeatedly in controlled human trials.[2][3][4][5]

The often-quoted “38” has a genuine experimental basis

A controlled crossover trial found that the average two-hour glucose response to trehalose was 38% of the response to glucose.[2]

Longer-term human research is continuing

Daily-consumption studies have produced interesting findings, particularly in participants with less favourable glucose regulation, although TREHA® should not be regarded as a treatment for diabetes.[6][7][8]

The bigger picture

Trehalose occupies an unusual position among sugars.

It is:

a genuine carbohydrate

a source of glucose

about 40% as sweet as sucrose

yet it produces a very different acute glucose and insulin response from consuming free glucose.

That combination is why it attracts attention across food science, metabolic research and sports-nutrition research.

For consumers interested in the metabolic characteristics of different carbohydrates, perhaps the most important point is also the simplest:

Not all glucose-containing carbohydrates reach the bloodstream in the same way.

TREHA® is a particularly clear example.

References & further reading

[1] Food Standards Agency. “Trehalose: Authorised Novel Food NOVEL-140.” Great Britain authorisation defining trehalose as a disaccharide of two glucose units and requiring foods containing it to carry the statement “Trehalose is a source of glucose.”
Food Standards Agency: Trehalose authorisation Food Data Downloads

[2] Yoshizane, Chiyo, et al. 2017. “Glycemic, Insulinemic and Incretin Responses after Oral Trehalose Ingestion in Healthy Subjects.” Twenty healthy adults consumed 25g trehalose and 25g glucose in a crossover study. The mean two-hour glucose-response ratio was 38% and the insulin-response ratio 36%.
Read the full study PubMed Central (PMC)

[3] Maki, Kevin C., et al. 2009. “Acute Effects of Low Insulinemic Sweeteners on Postprandial Insulin and Glucose Concentrations in Obese Men.” International Journal of Food Sciences and Nutrition. Trehalose-containing drinks reduced glycaemic and insulinaemic incremental AUC by approximately 20–35% compared with glucose.
View on PubMed PubMed

[4] van Can, Judith G. P., et al. 2009. “Reduced Glycaemic and Insulinaemic Responses Following Trehalose Ingestion: Implications for Postprandial Substrate Use.” Trehalose produced lower glucose and insulin responses than glucose both as a carbohydrate drink and when incorporated into a mixed meal.
View on PubMed PubMed

[5] van Can, Judith G. P., et al. 2012. “Reduced Glycaemic and Insulinaemic Responses Following Trehalose and Isomaltulose Ingestion: Implications for Postprandial Substrate Use in Impaired Glucose-Tolerant Subjects.” British Journal of Nutrition 108:1210–1217.
View on PubMed PubMed

[6] Mizote, Akiko, et al. 2016. “Daily Intake of Trehalose Is Effective in the Prevention of Lifestyle-Related Diseases in Individuals with Risk Factors for Metabolic Syndrome.” Double-blind trial comparing 10g/day trehalose with sucrose for 12 weeks.
View on PubMed PubMed

[7] Yoshizane, Chiyo, et al. 2020. “Daily Consumption of One Teaspoon of Trehalose Can Help Maintain Glucose Homeostasis: A Double-Blind, Randomized Controlled Trial Conducted in Healthy Volunteers.” Fifty participants consumed 3.3g/day trehalose or sucrose for 78 days.
View on PubMed PubMed

[8] The Effects of Oral Trehalose on Glycaemia, Inflammation, and Quality of Life in Patients with Type 2 Diabetes. 2023. Double-blind randomized pilot trial comparing 3.3g/day trehalose and sucrose for 12 weeks.
View on PubMed

9] Department of Health and Social Care. Great Britain Nutrition and Health Claims Register and Guidance. Only authorised health claims may be used in commercial communications in Great Britain.
GB Nutrition and Health Claims Register