Encrypt your data before you enter it in the database. As far as I know, the SQLite database is kept in a single file somewhere in the /data/ directory. What is more, your data is kept in plain text format. This means that it will always be possible for someone to extract that data by rooting the phone, obtaining the .db SQLite file and opening it with a text editor.
So, encrypt your data :)
--
Okay, maybe not a text editor, but a simple hex editor. Anyways...
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…