Glucose screening

What is a normal range for this test? All the resources I have looked at online and in my nursing textbooks say 140-199 is high and anything below 140 is normal. I just took the glucose screening and I had 136, my office said anything below 135 is normal and that I need to complete the 3 hour test. This is my second pregnancy and have no history of diabetes or gestational diabetes in my family or previous pregnancies.