Adding points to the glucometer reusult to arrive the correct glucose level?

I recently bought one touch ultra 2 glucometer. The glucometer is working well. but i am told by my friend that we should add 10 to 12 points to arrive at the correct glucose leveI . Is it so, ? The brochure also indicating that the glucometer reuslt and the lab result very at 20% . will anybody explain clearly to me