Glucose Test Help!!

Okay so i failed my 1 hour glucose test, the nurse didn't say by how many points. But they are having me retake the test, which is the 3 hour one. I was told no eating for 12 hours before the test. At the first glucose test they checked my blood. I read online that they check several times throughout the 3 hours. I was wondering will they check by blood samples or urine samples? Thanks!