Insulin ResistanceNCT06925451
Effects of Sourdough Fermentation Duration and Acid Development on Postprandial Blood Glucose in Prediabetic Adults
A study testing sourdough bread 24, sourdough bread 48 and sourdough bread 72 in people with Insulin Resistance, run by Arizona State University at 1 site in United States.
Trial summary
The primary intervention for management of prediabetes is lifestyle changes. Eating healthier and increasing physical activity was found to slow the progression of prediabetes into diabetes, reduce the risk of other diseases like cardiovascular disease and hypertension, and have a lasting impact even after the… Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Insulin Resistance
- What is being tested?
- sourdough bread 24, sourdough bread 48 and sourdough bread 72
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 5 participants
- Where
- 1 siteUnited States
- Study dates
- 4 Apr 2025to 15 Dec 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- prediabetes; not on metformin; no known food allergies or sensitivities; not supplementing pre/post biotics
Who cannot join
- following diet that restricts carbohydrates; medication use affecting blood glucose; acute illness; smoker; pregnant; lactating; GI tract surgery; not willing to follow protocol
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Effects of Natural Sourdough Fermentation Duration and Acid Development on Postprandial Blood Glucose in Prediabetic Adults
The primary intervention for management of prediabetes is lifestyle changes. Eating healthier and increasing physical activity was found to slow the progression of prediabetes into diabetes, reduce the risk of other diseases like cardiovascular disease and hypertension, and have a lasting impact even after the intervention is discontinued. Studies found that increasing the intake of fiber, pre- and probiotics, and fermented foods have been linked to improved glycemic biomarkers. The goal of this crossover randomized trial is to assess the relationship between lengthened fermentation time of sourdough bread, e.g., an increased amount of lactic acid and acetic acid in the bread product, and postprandial glycemic response in healthy adults with prediabetes.
Read the detailed description
Sourdough bread has been proven to have higher fiber content and contains beneficial microorganisms from the fermentation process and has been linked to reduced risk of various diseases like diabetes, cardiovascular disease, and dyslipidemia. The fermentation of sourdough bread products converts starch and sugar in the dough into resistant starches and other slower digesting compounds. Sourdough bread products also have a lower glycemic index value, meaning they do not cause the blood sugar to rise as quickly, thus slowing the release of insulin in the body, leading to reduced risk of insulin resistance. However, very few studies exist studying the effects of naturally fermented sourdough products in individuals with prediabetes. It is worth exploring if increasing the fermentation time of naturally fermented sourdough bread increases the effects on relevant biomarkers relating to postprandial glycemia and insulinemia in prediabetic adults.
This study examined the acute effect of varying lengths of sourdough fermentation times on postprandial blood glucose levels over a 4-week period in adults with prediabetes (as evidenced by fasting glucose ≥100 or diagnosis by physician), but not taking diabetic medications. For each trial, the sourdough bread was ingested after an overnight fasting period in order to evaluate the effects of the bread when incorporated into the diet in place of breads made with baker's yeast. The goal of this crossover randomized trial was to assess the relationship between lengthened fermentation time, meaning an increased amount of lactic acid and acetic acid in the bread product, and glycemic and insulinemic response.
- Conditions
- Insulin Resistance
- Being tested
- sourdough bread 24, sourdough bread 48, sourdough bread 72, yeast bread
- Keywords
- fermentation, pre-diabetes, sourdough bread, post-prandial glycemia
- Medical subject headings
- Insulin Resistance, Glucose Intolerance
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
sourdough bread 24Other
fermentation time=24 hours
sourdough bread 48Other
fermentation time=48 hours
sourdough bread 72Other
fermentation time=72 hours
yeast breadOther
no fermentation
| Study group | Role | What they receive |
|---|---|---|
| sourdough bread 24 | Experimental | 24 hours fermentation Receives: Other: sourdough bread 24 |
| Control bread | Active comparator | 12 hours fermentation Receives: Other: yeast bread |
| sourdough bread 48 | Experimental | 48 hours fermentation Receives: Other: sourdough bread 48 |
| sourdough bread 72 | Experimental | 72 hours fermentation Receives: Other: sourdough bread 72 |
What is being measured
The primary outcome is the main question the study is designed to answer.
blood glucose
blood glucose will be measured using a glucometer and capillary blood from finger prick
Measured: conducted at fasting and 30, 60, 90, and 120 minutes post-meal
Secondary outcomes (2)
hunger rating
Hunger rating will be determined using Likert scale. Anchors: not hungry at all and as hungry as I have ever felt. A higher score indicates greater hunger.
Measured: conducted at 120 minutes post-meal
bread palatability
bread palatability will be measured by Likert scale
Measured: conducted at 120 minutes post-meal
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted13 Apr 2025
- Study start4 Apr 2025
- Primary completion15 Aug 2025
- Study completion15 Dec 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Insulin ResistanceStudies of the same condition, open and under way.
- More trials run by Arizona State UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- The day prior to testing is standardized: no vigorous activity or alcohol consumption, and two bagels are to be consumed between 3 pm and 8 pm. Participants will begin an overnight fast starting around 10 pm (only water is to be consumed). The bagels will be provided at no charge. For each of the 4 test visits, participants arrive in a fasted state and a blood drop will be collected via finger prick to measure glucose. The 'test meal' will be consumed under observation within 8 minutes. The three fermented versions on the sourdough bread and the control bread will be fed using a four-block randomization process. Finger pricks will take place at 30, 60, 90, and 120 minutes post meal. The participant will be asked to complete hunger measures and report on the acceptability of the bread at the completion of testing.
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 5 participants (actual)
Sponsor and investigators
- Lead sponsor
- Arizona State University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Carol Johnston, Arizona State University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06925451
- Sponsor's protocol ID
- STUDY00021470
- Status last verified
- Aug 2025
- First submitted
- 6 Apr 2025
- Last updated
- 23 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: We do not plan to publish in ICMJE journals
Study at a glance
From the registry record, last updated by the sponsor on 23 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Natural Sourdough Fermentation Duration and Acid Development on Postprandial Blood Glucose in Prediabetic Adults
- ClinicalTrials.gov ID
- NCT06925451
- Acronym / sponsor ID
- STUDY00021470
- Conditions
- Insulin Resistance
- Keywords
- fermentation, pre-diabetes, sourdough bread, post-prandial glycemia
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 5 participants (actual)
- Lead sponsor
- Arizona State UniversityUniversity, hospital or other
- Study start
- 4 Apr 2025 (actual)
- Primary completion
- 15 Aug 2025 (actual)
- Study completion
- 15 Dec 2025 (actual)
- First posted
- 13 Apr 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The primary intervention for management of prediabetes is lifestyle changes. Eating healthier and increasing physical activity was found to slow the progression of prediabetes into diabetes, reduce the risk of other diseases like cardiovascular disease and hypertension, and have a lasting impact even after the intervention is discontinued. Studies found that increasing the intake of fiber, pre- and probiotics, and fermented foods have been linked to improved glycemic biomarkers. The goal of this crossover randomized trial is to assess the relationship between lengthened fermentation time of sourdough bread, e.g., an increased amount of lactic acid and acetic acid in the bread product, and postprandial glycemic response in healthy adults with prediabetes.
Detailed description
Sourdough bread has been proven to have higher fiber content and contains beneficial microorganisms from the fermentation process and has been linked to reduced risk of various diseases like diabetes, cardiovascular disease, and dyslipidemia. The fermentation of sourdough bread products converts starch and sugar in the dough into resistant starches and other slower digesting compounds. Sourdough bread products also have a lower glycemic index value, meaning they do not cause the blood sugar to rise as quickly, thus slowing the release of insulin in the body, leading to reduced risk of insulin resistance. However, very few studies exist studying the effects of naturally fermented sourdough products in individuals with prediabetes. It is worth exploring if increasing the fermentation time of naturally fermented sourdough bread increases the effects on relevant biomarkers relating to postprandial glycemia and insulinemia in prediabetic adults.
This study examined the acute effect of varying lengths of sourdough fermentation times on postprandial blood glucose levels over a 4-week period in adults with prediabetes (as evidenced by fasting glucose ≥100 or diagnosis by physician), but not taking diabetic medications. For each trial, the sourdough bread was ingested after an overnight fasting period in order to evaluate the effects of the bread when incorporated into the diet in place of breads made with baker's yeast. The goal of this crossover randomized trial was to assess the relationship between lengthened fermentation time, meaning an increased amount of lactic acid and acetic acid in the bread product, and glycemic and insulinemic response.
Study design
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (participant)
- Number of arms
- 4
- Model description
- The day prior to testing is standardized: no vigorous activity or alcohol consumption, and two bagels are to be consumed between 3 pm and 8 pm. Participants will begin an overnight fast starting around 10 pm (only water is to be consumed). The bagels will be provided at no charge. For each of the 4 test visits, participants arrive in a fasted state and a blood drop will be collected via finger prick to measure glucose. The 'test meal' will be consumed under observation within 8 minutes. The three fermented versions on the sourdough bread and the control bread will be fed using a four-block randomization process. Finger pricks will take place at 30, 60, 90, and 120 minutes post meal. The participant will be asked to complete hunger measures and report on the acceptability of the bread at the completion of testing.
| Arm | Type | Receives |
|---|---|---|
| sourdough bread 24 | Experimental | Other: sourdough bread 2424 hours fermentation |
| Control bread | Active comparator | Other: yeast bread12 hours fermentation |
| sourdough bread 48 | Experimental | Other: sourdough bread 4848 hours fermentation |
| sourdough bread 72 | Experimental | Other: sourdough bread 7272 hours fermentation |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (1 listed)
- prediabetes; not on metformin; no known food allergies or sensitivities; not supplementing pre/post biotics
Key exclusion criteria (1 listed)
- following diet that restricts carbohydrates; medication use affecting blood glucose; acute illness; smoker; pregnant; lactating; GI tract surgery; not willing to follow protocol
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| sourdough bread 24fermentation time=24 hours | Other | sourdough bread 24 |
| sourdough bread 48fermentation time=48 hours | Other | sourdough bread 48 |
| sourdough bread 72fermentation time=72 hours | Other | sourdough bread 72 |
| yeast breadno fermentation | Other | Control bread |
Primary outcome
blood glucose
Time frame: conducted at fasting and 30, 60, 90, and 120 minutes post-meal
blood glucose will be measured using a glucometer and capillary blood from finger prick
2 secondary outcomes
hunger rating
Time frame: conducted at 120 minutes post-meal
bread palatability
Time frame: conducted at 120 minutes post-meal
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 23 Jan 2026.
- Individual participant dataSharing planned: No. We do not plan to publish in ICMJE journals
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing sourdough bread 24, sourdough bread 48 and sourdough bread 72 in people with Insulin Resistance, run by Arizona State University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 23 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
blood glucose (time frame: conducted at fasting and 30, 60, 90, and 120 minutes post-meal). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 23 Jan 2026.