The reaction is difficult to bring about directly. It will usually turn into a charred, black mess if you try to burn it in a flame, however, in the body, sugar is metabolized at 37 o C in a series of biochemical reactions. Each step is catalyzed by a particular enzyme adapted for that purpose. The reactant, called the substrate fits into a specific site on the enzyme surface and is held in place by intermolecular forces. There, it can react with another species.
Inhibitors are substances which diminish the activity of an enzyme.
One way they do this is to occupy the space on the enzyme where the substrate is supposed to fit. These usually have a structure similar to that of the substrate they replace. The structures of enzymes have been studied with x-ray crystallography.