Glucose challenge test. Need to do?.

My wife is 26 weeks pregnant. Doctor asked her to take gct test but she did not mention what method of gct test need to do?. So we went to the lab and showed the doctor prescription test. They also not sure what method of gct need to do. Finally they themselves decided and collected the blood sample. We don't know whether they have done correctly or not. Please tell. Initially the have taken fasting blood sample and urine sample. Then they gave her 75 grams of glucose to drink.. That is almost 1 and half glass she drank. Then after 1 hours they again took blood and urine sample. Result came as 136 unit which was taken after drinking glucose and 78 unit which was taken during fasting sample. Please advise whether lab procedure is correct because I am afraid whether she would have drank lot of glucose at that time