ISO 26642 vs WS/T 652: Why the GI Test Method Matters More Than the Number

ISO 26642 vs WS/T 652: Why the GI Test Method Matters More Than the Number

If you buy low-GI products for retail or institutional channels, you will eventually be shown a GI value by someone who wants to sell you something. The number will usually look convincing. The question that determines whether it is useful is narrower: how was that number obtained?

Why the method matters more than the figure

Glycemic index describes how quickly a carbohydrate raises blood glucose after intake — not how much carbohydrate is present. That distinction is why the measurement approach defines the number's meaning. A GI figure is only transferable between markets if the testing protocol behind it is recognised.

Two standards dominate this field. ISO 26642 is the international method for determining the glycaemic index of foods, and it is the reference most international buyers and retailers expect to see. WS/T 652-2019, Determination of Food Glycemic Index, is the Chinese national health standard issued by the National Health Commission.

They are not competing claims. They address the same question, and a supplier operating to the Chinese national standard is working within a recognised framework — one that requires the determination of GI values to be conducted through human clinical trials rather than calculation or estimation.

Why human trials change the answer

This is the distinction most often blurred in the market. Glycaemic response varies considerably between individuals. A value derived from a small panel of human subjects, following a defined fasting and dosing protocol, captures real physiological response. A value inferred from a composition table does not, because carbohydrate quantity alone does not predict how blood sugar behaves.

For buyers, the practical implication is straightforward. When a supplier states a GI value, ask what the testing basis is before anything else. If the answer is a calculation, the figure is an estimate. If the answer is a human clinical trial conducted against a named standard by an accredited laboratory, the figure is defensible.

The three documents to request

Procurement teams can screen most suppliers with a short document request.

First, the GI test report, stating the standard used, the accredited laboratory, the sample, and the resulting value. Second, the certification for the low-GI claim itself, issued by a body authorised by the relevant accreditation authority — for products manufactured in China, this is CNCA, the Certification and Accreditation Administration. Third, food-safety certifications covering the specific production facility, since the claim and the factory are separate questions and a buyer should see evidence for both.

Where Detective No.55 sits

Every product carrying a low-GI claim in our range has passed human clinical GI testing, with values determined under WS/T 652-2019 and certified by an organisation authorised by CNCA. Production runs in class 100,000 clean workshops, with nutritional and GI components verified by dual-accredited CMA and CNAS laboratories.

We are not the only supplier able to present a GI number. What we can present is the full chain behind it: the standard, the testing basis, the laboratory, and the certification — the elements a buyer needs in order to defend the claim downstream, to their own regulator and to their own customers.

If you are qualifying low-GI suppliers and want to see what complete documentation looks like, we can send the relevant reports for the products you are interested in.📧 [email protected]