Glycemic index and fructose?
Many foods which show low on the glycemic index are extremely bad for anyone especially one with diabetes even though they have a low glycemic index. This is especially true for fructose and agave (agave being 90% or so fructose). Since these do not readily turn into glucose (being six carbon isomers) they have a low glycemic index, however they still glycate (in this case actually fructosylate) at at least a 10x greater rate than glucose.
Fructose also is metabolized in the liver turning into triglycerides (rather than glucose) and contributing to fatty liver and hepatic insulin resistance, and high serum triglycerides. Fructose has been used for decades in laboratory animals to turn them into diabetic subjects for experimentation. In other words, you should minimize dietary fructose even though it has a low glycemic index.
This illustrates the point that the glycemic index is far from a perfect index to use to determine healthy foods but is good for illustrative purposes as far as blurring the separation between simple and complex carbohydrates.
Also, the glycemic index does not reflect necessarily the glucose load and even less so the total sugar load, as it only measures one sugar, namely glucose.