Glucose
Glucose (or dextrose) is produced by enzymatic decomposition from starch and can be very quickly absorbed. It is a valuable substitute for ordinary sugar if you suffer from Fructose Malabsorption or Fructose Intolerance, and it is available at most supermarkets.
All commercially available dextrose contains up to 10% crystallized water, meaning that the water is bound in the crystal structure of the dextrose, but is freed when the dextrose is dissolved, e.g. in a cake batter. This is the reason that dextrose often makes doughs or other dishes more liquified. A good rule of thumb is that when using 1kg dextrose, expect it to add about 85ml of water. However, Frusano's Corn Sugar doesn't contain any crystallized water and is suitable for baking and cooking.