It's not necessarily that you failed 1 of 4 tests. It all depends on which timed draw that the 165 glucose was at. Did you have a 3 hr tolerance? Most pregnant women will have a 1 hr done +/-28weeks. Then if that is elevated the dr will order a 3hr Gtt. They will take a fasting glucose level then give you the glucola to drink. The draws after that are at 1hr, 2hr, 3hr and they watch the level of glucose rise, then fall. That's how they determine if one is a gestational diabetic. There are certain ranges that the glucose should be in. Good luck. If you have any questions, feel free to ask.