Rinse your mouth out with water, and either swallow or spit it out. Don't brush your teeth without first rinsing (after eating glucose tablets); otherwise, you can scratch the enamel off your teeth with the glucose tablets.
This is what my dental hygienist recommends, and I'll take her word for it. It makes sense, and I can't see whether my enamel's been getting scratched. In any case, if you have diabetes, take care of your dental health!