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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
Using individual food glycaemic index (GI) values to predict the GI of a meal in healthy people and comparing this estimated GI with the GI obtained from the people consuming the meal
Scientific title
Assessing in people with normal glucose tolerance how the formula used for estimating meal glycaemic index compares with a directly measured meal glycaemic index
Secondary ID [1] 259662 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Glucose tolerance 261231 0
Condition category
Condition code
Diet and Nutrition 259376 259376 0 0
Other diet and nutrition disorders

Study type
Description of intervention(s) / exposure
The glycaemic index (GI) of a meal is not normally measured, it is calculated according to a formula using the GIs of the individual foods contributing to the meal. It has been suggested that this predictive method is inaccurate. We therefore designed a study to test how the GIs of three meals, obtained using the predictive formula, compared with the direct determination of the GIs of the meals. The three meals all comprised a portion of chicken, sweet potato, peas, carrots and sauce having a combined carbohydrate content of 25 g. Another 25 g of carbohydrate was provided by including in the meal either potato, rice or pasta.The meals were approximately equicaloric (2100 kJ) and contained approximately 55% carbohydrate, 27% fat and 18% protein. Each meal was consumed comfortably within 15 minutes. Each participant consumed each of the meals with at least two days between successive tests. Participants were given a standard protocol to follow including an overnight fast.
Intervention code [1] 258090 0
Comparator / control treatment
Three meals were consumed and the GIs of the meals directly measured. These GI values were compared with the meal GIs estimated from knowing the GI of each of the foods contributing to the meal and summing them up using a mathematical formula.
Control group

Primary outcome [1] 262193 0
The primary outcome is the comparison of meal GIs obtained using two methods, direct measurement and estimation. Direct measurement involved measuring postprandial hyperglycaemia in response to a glucose reference beverage and to each of the meals at intervals over 2 hour periods. The GIs of each of the meals was subsequently calculated by expressing the blood glucose incremental area under the curve of each meal relative to the glucose reference beverage. Estimation involved determining the GIs of each of the carbohydrate foods contributing to the meals and summing the GIs according to a formula.
Timepoint [1] 262193 0
Two hours postprandially
Secondary outcome [1] 273300 0
The secondary outcome is to examine how the postprandial blood glucose concentrations obtained following the consumption of three test meals compare.
Timepoint [1] 273300 0
Two hours postprandially

Key inclusion criteria
Minimum Age 18 - 65 y
Both males and females
Healthy volunteers
Minimum age
18 Years
Maximum age
65 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Diabetes mellitus
Cardiovascular disease

Study design
Purpose of the study
Educational / counselling / training
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
The GIs of individual foods were tested in the participants and meal GIs calculated using the formula. The participants were then crossed over, consumed each of the three meals and the GI of the meals was directly determined.
Not Applicable
Type of endpoint(s)
Statistical methods / analysis

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 3221 0
New Zealand
State/province [1] 3221 0

Funding & Sponsors
Funding source category [1] 258551 0
Name [1] 258551 0
University of Otago
Address [1] 258551 0
Department of Human Nutrition
PO Box 56
Dunedin 9054
Country [1] 258551 0
New Zealand
Primary sponsor type
University of Otago
Department of Human Nutrition
PO Box 56
New Zealand
Secondary sponsor category [1] 257687 0
Name [1] 257687 0
Not applicable
Address [1] 257687 0
Not applicable
Country [1] 257687 0

Ethics approval
Ethics application status
Ethics committee name [1] 260519 0
University of Otago Human Ethics Committee
Ethics committee address [1] 260519 0
PO Box 56
Dunedin 9054
Ethics committee country [1] 260519 0
New Zealand
Date submitted for ethics approval [1] 260519 0
Approval date [1] 260519 0
Ethics approval number [1] 260519 0

Brief summary
The study was designed to test how well the GI of a meal could be predicted using the GIs of individual foods and summing them up according to a commonly used formula.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 32259 0
Address 32259 0
Country 32259 0
Phone 32259 0
Fax 32259 0
Email 32259 0
Contact person for public queries
Name 15506 0
Bernard Venn
Address 15506 0
University of Otago
Department of Human Nutrition
PO Box 56
Dunedin 9054
Country 15506 0
New Zealand
Phone 15506 0
Fax 15506 0
Email 15506 0
Contact person for scientific queries
Name 6434 0
Bernard Venn
Address 6434 0
University of Otago
Department of Human Nutrition
PO Box 56
Dunedin 9054
Country 6434 0
New Zealand
Phone 6434 0
Fax 6434 0
Email 6434 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary