She may not have been diagnosed. It is a difficult disorder to diagnose because the symptoms can resemble several other disorders. If you talk to individuals who have been diagnosed as bipolar, they will likely tell you that they were assessed by several doctors and it took quite some time before they were diagnosed.
Thought you might be interested in this:
The suicide rate for bipolar individuals has been estimated to be between
15% and 50%, depending on the study (K.J. Tarnowski, personal communication, 1998).*
http://itech.fgcu.edu/&/issues/vol2/issue1/bipolar.htm