
everything that Doug said above, and if she is going low around the same time every night, it might be time for a minor basal adjustment prior to that time.
BTW, anyone who pumps can address these kinds of issues. They are not brand specific, but are more related to the pumping in general.
If you don't have it, I highly recommend the book, Pumping Insulin, by John Walsh. Just about every issue relating to treatment via today's pumps is covered.
Good luck!