I need to bake a cake without fructose, so all forms of granulated sugar and most syrups (including honey, agave & maple syrup) are out. I've heard of granulated dextrose but can't find it. I'd like to use Glucose Syrup instead of sugar but need to know how to alter the recipe to compensate for using a syrup instead of granulated sugar.
Dextrose in powder form is very easy to get a hold of! As mentioned before, it is a very common ingredient in brewing, and is readily available from homebrew stores. While not as cheap as traditional table sugar, it isn't expensive either. Search online to see if there are any homebrew stores local to you.
"Corn syrup" (not HFCS) is supposed to be a primarily glucose syrup, though some formulations contain dextrose. It should not have any fructose in it, though I don't know if any of the brands guarantee that. Karo syrup contained HFCS up until a year ago or so, but it's since been removed. Your best bet would be to contact the manufacturer(s) and ask.