How Laboratories Measure a Food’s Glycemic Index (GI)

Need food laboratory for glycemic index GI testing?

Glycemic Index (GI) Testing, or GI Value Measurements

The glycemic index is a scale for ranking carbohydrates (0-100) based on how they raise blood sugar. Low glycemic foods release glucose into the bloodstream gradually. High glycemic foods cause greater fluctuations in blood sugar and insulin levels because the body digests, absorbs, and metabolizes them faster. Eating high glycemic foods are good for exercise recovery and help replenish energy fast.

Determining the GI value of a food is a done in a laboratory or clinical research facility by feeding 10 healthy clinical subjects a portion of food containing 50 grams of carbohydrates and measuring their blood glucose for the next two hours. The area under the two-hour blood glucose response for the food is measured. Then, using the same 10 clinical subjects but on a separate occasion, they are fed a sugar glucose food and again have their blood glucose monitored. The GI value for the food is then determined by dividing the glucose level for the test food samples by the glucose level of the reference food samples. The final GI value of the food is the average for all 10 people tested.

GI Symbol

GI Symbol Program officially launched in July 2002. It helps consumers identify the GI value of foods and make informed choices regarding the foods they eat. Any foods displaying the symbol guarantees the testing from an accredited laboratory using the international standard. The American Diabetes Association has tables of the GI for various foods known as the International Tables of Glycemic Index and Glycemic Load Values: 2008.

Foods with a low GI include beans, walnuts, cashews, sunflower seeds, sesame seeds, most vegetables, peaches, strawberries, mushrooms and chilis, while high glycemic foods include glucose (sugar), high fructose corn syrup, white bread, white rice, breakfast cereals and white potatoes. A foods glycemic effect depends on the starch, fat, and protein content.

GI Testing Projects

Contract Laboratory has facilitated the following project from companies needing to know the GI value for their food products:

  • Food Laboratory needed for nutritional analysis and ISO standard GI testing on ice cream product to obtain the Low GI Symbol.
  • NABL Food Analytical Chemistry Laboratory needed for GI testing in rice sample.
  • Dietary Supplement Company needs Analytical Chemistry Laboratory for GI testing.
  • Food laboratory needed for performing glycemic index testing on cereals product.
  • Food laboratory needed for analysis of a low-calorie sugar-substitute for glycemic index.
  • LONG TERM TESTING. Food laboratory needed for ISO glycemic index testing of sugars according to ISO26642:2010 protocol.
  • Food laboratory needed for fruit testing: glycemic index of fruits.
  • Central Laboratory needed for GI Testing for human clinical trials.
  • Food Science Laboratory needed for conducting glycemic index experiment on a food product according to a protocol for measurement of RAG, SAG, and starch fractions by an in vitro technique is described, based on the measurement by HPLC of the glucose.
  • Clinical Laboratory needed for in vivo clinical trials involving human subjects for GI and glycemic load.

And many more which can be viewed at Incoming Laboratory Test Requests


Common food products needing Glycemic Index testing include breads, cereals, cookies, cakes, and bakery products. If you are a food manufacturer, distributor, importer, retailer or restaurant in need of a food laboratory for glycemic index testing, Submit Food Request on our website for free or by calling toll free 1-855-377-6821