"The Corn Refiners Association maintains that HFCS has essentially the same fructose/glucose proportions as sugar. It also says that fructose does not have a different effect on the body from glucose."
Fructose has to be metabolised by the liver, that is why it has a low Gi. It also glycosylates haemoglobin seven times as much as glucose. Glucose is essential for life; fructose isn't.
Fructose increases triglycerides to disrupt metabolism (such as insulin-resistance), then glucose causes excess insulin and IGF1release that causes growth of endothelial linings, increasing risk of heart disease.