For answers to your questions about GI Determination, visit our FAQ page.
Background and Qualifications
In 1981, the concept of the Glycemic Index was introduced by a group of scientists at the University of Toronto, led by Dr. David Jenkins and including Dr. Thomas Wolever and Dr. Alexandra Jenkins. At GI Labs, we are proud to have Dr. Thomas Wolever and Dr. Alexandra Jenkins, pioneers of the Glycemic Index, as two of our Senior Scientists.
All of our Senior Scientists at GI Labs have a continued dedication to research involving the Glycemic Index that has spanned decades. Our Senior Scientists are well-known experts in this field, continually contributing to academic research about the Glycemic Index. This makes our Senior Scientists the perfect Principal Investigators for the Glycemic Index determination of your product(s).
GI Determination at GI Labs
Having the Glycemic Index of your product determined at Glycemic Index Laboratories by the pioneers of the Glycemic Index ensures that your study is done properly by a well-recognized clinical research laboratory.
Upon completion of your study, you will receive a final report, detailing the methods used to determine the Glycemic Index of your product and presenting the determined GI value of your product.
You will be able to use the GI Labs Service Mark on your product label or website, to indicate that your product was properly tested at GI Labs, upon signing the Service Mark contract and abiding by its terms. GI Labs is also pleased to provide our clients with a GI determination certificate upon request.
Protocol and Methods
At GI Labs, our Glycemic Index determination protocol fully complies with ISO 26642:2010, Determination of the glycaemic index and recommendation for food classification.
The standard glycemic index determination protocol requires that ten normal subjects are studied on multiple occasions (maximum 3 per week) in the morning after an overnight fast. After 2 fasting blood samples are taken, subjects eat a test meal containing 50g available carbohydrate and have further blood samples taken at 15, 30, 45, 60, 90 and 120 minutes after starting to eat. Capillary blood is obtained by finger-prick and whole blood glucose is determined on-site in our laboratory with an automatic analyzer using the glucose oxidase method.
Each subject conducts one trial of each test food and 2-3 trials of the reference food. The reference food can be dextrose or white bread, analyzed so its composition is exactly known, and baked in our test kitchens. If a large number of foods is being tested, a reference food trial will be done for every 6-7 test foods. This ensures that there are no changes in subject's glucose responses with time.
Blood samples are analyzed in our laboratory by our specially-trained technicians. The resulting glucose values are used in mathematical formulas to calculate the glycemic index value(s) of your product(s).
In addition to our standard GI protocol, we have also developed protocols for situations where food products are not appropriate for GI testing or where a direct comparison of different ingredients is desired. One of our Senior Scientists will be pleased to discuss your specific requirements to determine the most appropriate test method for your product(s).
Once you have decided to have the Glycemic Index of your product(s) determined at GI Labs, you will be asked to sign the GI Labs Terms of Research. Our Director of Research will ask you to provide a macronutrient analysis for your product(s). This will allow our Director of Research to determine the amounts of your product(s) required for testing. Once you provide GI Labs with the required amount of test product(s) and sign the Terms of Research, the testing will begin. Testing generally takes approximately one week per food plus 4 weeks. Upon completion of your testing, you will receive a final report detailing your product's Glycemic Index value signed off by the Principal Investigator.
For more information about glycemic index determination at GI Labs, visit the following pages:
- Frequently Asked Questions
- GI and Health
- Consumer Awareness of the GI
- Regulatory Environment
- Certification Mark