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GI Determination

Frequently Asked Questions

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Getting Started

Is my product eligible for GI testing?

The Glycemic Index is a measure of how the carbohydrate in a given food affects blood glucose levels. Products need to contain sufficient amounts of digestible carbohydrate to be eligible for GI testing. If your product is very low in digestible carbohydrate, there are alternative ways of measuring your food's impact on blood sugar. To find out if your product is eligible for GI testing, contact us.

My product is not suitable for GI determination. Can you suggest other options?

There are other testing options for products that are not suitable for GI determination. To learn about the best type of testing for your product, contact us.

What if I want the GL of my product determined?

GI Labs is pleased to offer Glycemic Load determination.

Can the GI of my product be calculated?

The Glycemic Index is a measure of the effect of carbohydrate on blood glucose levels. The only way to determine this effect is to feed the food to individuals and measure their blood glucose levels before and after eating the test food. GI values are affected by many factors (including carbohydrate source, chemical structure, processing, cooking technique, etc.). Therefore, they cannot be calculated and must be clinically tested, as outlined in ISO 26642:2010, Determination of the glycaemic index and recommendation for food classification.

Is in vitro testing available?

In vitro GI determination gives a rough indication of where a food's GI value may lie. In vitro GI determination does not comply with the ISO standard for GI determination and therefore the values it produces are not recognized as official values. However, in vitro GI determination can be a useful for product development, screening various formulations of a product to determine which is most likely to have the desired GI value. This testing would then be followed by in vivo GI determination of the chosen formulation. In vitro GI determination is not offered by GI Labs, but we can recommend analytical laboratories that perform this type of testing.

Do I need to test each flavour of my product separately?

If different flavours of your product have essentially the same macronutrient composition and have only minor differences that do not affect the carbohydrate quality of the product, flavours may be able to be combined for GI determination. To find out if a specific porotocl for GI determination may apply to your products, contact us.

If I reformulate my product, do I need to retest its GI value?

Reformulation may affect the GI of the carbohydrates in your product and so it may need to be retested. GI Labs' Director of Research will review the reformulation changes to determine if retesting is recommended or necessary.

Why choose GI Labs?

At GI Labs, we are proud to provide our clients with the highest quality clinical nutrition research. Our senior scientists, Dr. Thomas Wolever and Dr. Alexandra Jenkins, are widely recognized for their expertise in nutrition research, which they will share in determining how to best address your research objectives. Together with our Senior Scientists, our dedicated Clinical Research Coordinators and skilled Laboratory Technicians provide you with the highest quality clinical nutrition research in a timely manner to achieve your goals.

What's involved with GI Determination?

What are the steps to initiate research?

To view the steps to initiate research, please click here.

How long does GI testing take?

Once GI Labs has the received the required amount of products for testing as well as the signed Terms of Research agreement and initial deposit, testing takes approximately 1 week per food plus 4 weeks for reference tests, analysis, calculations, and report preparation. Therefore, a study with 1 test food would take approximately 5 weeks, while a study with 10 test foods would take approximately 14 weeks. Upon the completion of your study, you will receive a final report detailing your product's Glycemic Index value.

How much does GI testing cost?

To receive our price list, contact us.

What information do I need to send you to get testing started?

For GI determination, we will need the macronutrient content of your products. To ensure the best accuracy, we recommend that the macronutrient information is determined using a laboratory rather than food tables, although both are acceptable. Once you send us the macronutrient composition and the ingredient list of your product, we will be able to tell you whether your product qualifies for the standard protocol, estimate the quantities of your product which we require and can give you a firm quote. You will be asked to send GI Labs the specified amount of test product(s), send the initial deposit, and sign the Terms of Research. Then testing can begin.

Where do I send samples of my product for testing?

Please send your product to:
Dr. Alexandra Jenkins
Director of Research
Glycemic Index Laboratories
20 Victoria St., 3rd Floor
Toronto, ON
M5C 2N8

Can you test my product in people with diabetes or other specific populations?

While standard GI testing occurs in the general population, GI Labs has an extensive subject pool and we are able to test products in populations with various health conditions, should you research objectives require it.

What can I do with the results of testing?

What can I say about the GI value on my product label?

In most countries, there are permissible ways to promote the GI as part of an overall strategy, and several companies are currently successfully marketing their low-GI products. We recommend you seek guidance from qualified experts who are well-versed in the regulatory and labeling regulations which apply to your particular markets. We are familiar with a number of successful GI marketing examples from around the world and would be pleased to share these with you.

Do you have a certification mark?

GI Labs is pleased to provide a Certification Mark for our clients. The GI Labs Certification Mark is available to all GI Labs clients for use on products that were tested at GI Labs and is free of charge. To learn more about the GI Labs Certification Mark, click here.

Will I get a certificate with my product's GI value?

GI Labs is pleased to provide certificates of analysis upon request.

Can the results of my research be published?

Research performed at GI Labs is of a standard to be eligible for publication in peer-reviewed scientific journals. Should you wish to have the results of your trial published in a scientific journal, speak to our Director of Research about manuscript preparation services. To view some examples of articles published based on research performed at GI Labs, click here.


Acute Testing

Long-Term Trials

Scientific Review

Senior Scientists


Dr. T. Wolever MD, PhD

Vice President

Dr. A. Jenkins PhD, RD