I think they're really focusing on glycemic index here rather than whole/non-whole wheat. The glycemic index of any food can be determined empirically (it's the

I think they're really focusing on glycemic index here rather than whole/non-whole wheat. The glycemic index of any food can be determined empirically (it's the AUC of the 2hr blood glucose response curve after ingesting a fixed amount of said substance). Usually, pure glucose is the reference food that is pegged at 100, and everything else is represented as the relative fraction compared to glucose.