When you are sleeping and get a low blood sugar, are you most likely to wake up or sleep through it?

Sleep through it. Odds are you will likely sleep though it, however you probably will wake up with a wet pillow from the sweating due to hypoglycemia and have high or highish glucose reading from the so called rebound phenomenon. I suggest you talk with your physician if you experience hypoglycemia frequently regardless of timing. Good luck.
Depends. Most likely you'll wake up with symptoms of profuse sweating, fast heartbeats, nightmare but there is a subset of people who can't feel low blood sugar (known as hypoglycemic unawareness) and could sleep through it.