Hi.  I'm very familiar with bipolar disorder -- I was married to a bipolar person for many years. 

First I would ask you:  What makes you suspect your wife is bipolar?  Personally, I wouldn't recommend speaking with her until you're absolutely positive.  If you can give some detail on what's making you think this, I could probably offer you more useful suggestions.

Please keep in mind that bipolar disorder is not something that can be controlled without medication.  Depending on its severity now and her age, it could get worse before it gets better.  It manifests differently in different people, and many bipolar people don't like the idea of medication because it takes away their "high."  Approaching her about this should be done very carefully if you wish her to get help.

You may wish to check out the Mayo Clinic's pages on Bipolar Disorder, as well.  Good luck!

Alkhemist