Do breads made from different grains increase blood sugar similarly? A study in healthy volunteers

ISRCTN	ISRCTN49467722
DOI	https://doi.org/10.1186/ISRCTN49467722
Sponsor	University of Bergen
Funders	Nofima, Universitetet i Bergen

Submission date: 22/12/2025
Registration date: 30/12/2025
Last edited: 30/12/2025

Recruitment status: Recruiting
Overall study status: Ongoing
Condition category: Nutritional, Metabolic, Endocrine

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Record updated in last year

Plain English summary of protocol

Plain English summary of protocol not provided at registration.

Contact information

Prof Jutta Dierkes
Principal investigator, Scientific, Public

Department of Clinical Medicine, Centre for Nutrition, Jonas Lies vei 86
Bergen
5021
Norway

ORCID ID	0000-0003-0663-877X
Phone	+4795448279
Email	jutta.dierkes@uib.no

Study information

Primary study design	Interventional
Allocation	Randomized controlled trial
Masking	Blinded (masking used)
Control	Active
Assignment	Crossover
Purpose	Basic science
Scientific title	Glycemic index of whole grain breads produced from different cereals: a randomized cross-over study in healthy volunteers
Study objectives	To investigate whether the blood glucose response is different after ingestion of whole grain bread prepared from oat, barley or rye compared to bread prepared from wheat. To investigate the glycemic index of whole grain breads prepared from different cereals. To investigate whether the insulin increase is different after ingestion of whole grain bread prepared from oat, barley, rye or wheat.
Ethics approval(s)	Approved 17/06/2025, Regional Committees for Medical and Health Research, Northern Norway (MH-bygget, 12th floor, Breivika, UiT Norges arktiske universitet (Tromsø), Tromsø, 9037, Norway; +47 776 46 140; rek-nord@asp.uit.no), ref: 900039
Health condition(s) or problem(s) studied	Postprandial glycemia in healthy volunteers
Intervention	Healthy adult volunteers fulfilling the inclusion criteria will be invited to the main study. The order of testing the different breads and the glucose will be in random order for each volunteer, with a washout period of at least 48 h between two tests. The volunteers will arrive at 8 am at the Research Unit, then a fasting blood sample is taken, and one of the breads is ingested in random order, within 10 minutes and in a blinded fashion (as this is an investigation with real food, difficulties in the blinding cannot be excluded, but will be minimized as far as possible). Further blood samples are taken at 15, 30, 45, 60, 90 and 120 minutes. Randomisation is performed using EasyTrial block randomisation. Breads: The breads will be produced at Nofima in a pilot-scale bakery (registered with Mattilsynet for commercial food production). Each bread will be portioned at Nofima to have 50 g available carbohydrate and then shipped frozen to Bergen and thawed before the test day. Glucose solution (50g) will be used for the calculation of the glycemic index. Blood sample taking: The participants will receive an intravenous catheter at each study day for sampling of venous blood for the measurement of glucose and insulin. Capillary glucose will be measured with the Hemocue Glucose 201 system, a point-of-care device recommended for monitoring of blood glucose. The Hemocue Glucose 201 system is based on the modified glucose dehydrogenase principle with photometric measurement of glucose.
Intervention type	Other
Primary outcome measure(s)	Incremental area under the curve between 0 and 120 min of capillary blood glucose measured using HemoCue Hb201+ analysers (mmol/L/min) at baseline, and after 15, 30, 45, 60, 90 and 120 minutes
Key secondary outcome measure(s)	Incremental area under the curve between 0 and 120 minutes of serum insulin measured using Siemens Immulite 2000 XPi chemiluminescence immunoassay (mU/L/min) at baseline, and after 15, 30, 45, 60, 90 and 120 minutes
Completion date	01/09/2026

Eligibility

Participant type(s)
Age group	Adult
Lower age limit	18 Years
Upper age limit	60 Years
Sex	All
Target sample size at registration	15
Key inclusion criteria	1. Healthy volunteers without known or unknown diabetes mellitus, excluded by a fasting glucose measurement and a measurement of HbA1c 2. Age range 18-60 years
Key exclusion criteria	1. Pregnancy 2. Breastfeeding 3. Reduced ability to give informed consent 4. Alcohol or other substance abuse 5. Use of drugs that may interfere with glucose concentrations 6. Chronic diseases like cardiovascular diseases, cancer, or chronic obstructive lung disease are a reason for exclusion when they occurred during the last three years and require continued treatment 7. Diabetes mellitus
Date of first enrolment	01/10/2025
Date of final enrolment	30/05/2026

Locations

Countries of recruitment

Norway

Study participating centres

Results and Publications

Individual participant data (IPD) Intention to share	No
IPD sharing plan summary	Data sharing statement to be made available at a later date
IPD sharing plan

Study outputs

Output type	Details	Date created	Date added	Peer reviewed?	Patient-facing?
Protocol file			23/12/2025	No	No

Additional files

48715_Protocol.pdf: Protocol file

Editorial Notes

30/12/2025: Study’s existence confirmed by the Regional Committees for Medical and Health Research, Northern Norway.