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% crystal water, meaning that the contained 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 crystal water and is suitable for baking and cooking.
Additional disadvantages of dextrose are what some sense as a “metallic” taste, a tendency to crystallize that is often a result of cooling (forming a whitish coating which is often mistaken for mold), and very fast increase in blood sugar levels due to its quick absorption. In order to avoid these challenges, Frusano uses glucose syrup rather than pure glucose.