This may help.

AUC should be calculated from the OGTT experiment while the glycemic index can be calculated as AUC (product)/AUC (control).

I hope this help.

AUC will be calculated from oral glucose tolerance assay experiment while GI is calculated as the incremental area under the blood glucose response curve of a 50 g carbohydrate portion of the test food taken by the subject to the same amount of carbohydrate from a standard food taken by the same subject expressed as a percentage (FAO, 1998) 

Thank you all for your answers!

I'm conducting the GI experiment in animals (male wistar rats) and the product used of which GI needs to be estimated is a cereal+chicken product. I intend to study the mixed meal effect of these ingredients together.

The control group is force-fed with pure glucose solution and the product is also fed the same way (slurry form).

The product developed has a serving size of 50 g (the whole product) for a normal adult. The calculation to decide amount of corresponding feed to be given to the animals was done using the appropriate conversion table.

Do I need to  calculate the feed based on an equivalent amount of carbohydrate? or shall I feed the animals with the calculated feed amount, as my intention is to study how the entire 50g product would effect the GI invivo? (mixed meal effect)

Is there a separate protocol to conduct GI estimation in anmals, if so, kindly attache relevant files here.

I hope I was able to make my point.

Kindly suggest!

Thank you all!

The AUC is estimated based on measures of blood glucose concentration obtained at various instants in time. Usually, glucose is measured at 15–30 min intervals, and to determine AUC one has to estimate what is happening to blood glucose between the times when it is measured.

The GI is defined as the incremental area under the blood glucose response curve elicited by a 50 g available carbohydrate portion of a food expressed as a percentage of the response after 50 g anhydrous glucose taken by the same subject. The GI was originally meant to be an index of the blood glucose raising potential of the available carbohydrate in foods.

Sea the attached files for calculation the area under the curve for glycemic index estimation

Shefali Bhardwaj In the following video tutorial, I have discussed how to calculate area under the curve using Origin. Area under the curve signifies many physical and geometrical interpretations in Science. It’s a product of the quantities (functions) on the x and y axes. The video explains all the steps to be performed to calculate area under a specific curve. In the case you want to further ask about it, please do comment on the specific video, I'll respond to it shortly. I have provided the practice file here. Thanks

https://youtu.be/DMsBzGCNHQk