I'm not entirely sure which glucose test you're referring to, since fasting glucose, random glucose, and the GD screening test all have different reference ranges. It might be worth clarifying with your doctor or PD which test this reading is from, because 6.8 could mean different things depending on the context and units used. Bringing the actual lab report along when you see them would help, so they can explain what the result means for your specific situation.
no it is not high, less than 7.8, one hr after meals is considered as normal