I'm not really sure at how long it will last but I read somewhere that it can turn rancid. So maybe you can taste it and see? And also keep it refrigerated..hope somebody else has a better answer!
don't store glucose in the refrigerator - it will just totally harden. due to its extremely high sugar content, glucose will pretty much last forever. well, not forever, but a very, very long time - keep in a covered container at room temperature.
