This is actually quite an interesting topic; I'm a biochemistry student so I'd be interested in finding out which 'chemical reagents' are used. There are simple chemical tests for glucose but I wonder if an ELISA (Enzyme-Linked Immunosorbent Assay) is a better option.
I guess that you could produce an ELISA (I don't know of one) on the assumption that you could produce a suitable antibody to glucose and then successfully conjugate it to a suitable enzyme such as HRP. We then used to use Phenolphthalein Monophosphate as a color reagent. Of course if you got a suitable antibody then the world is open to any technique you like such as FIA or RIA.