Can my Google Docs app be secured? I have sensitive information in my Google Docs.  

I enabled two-step verification with my Google account; but just noticed that Google DOCS on my phone doesn't require any type of PIN number or password when I open it.  Is there a way to secure this app?

NOTE:  I also have a PIN number that must be entered after swipe.
All you need is an app locker app. There are many app lockers in Play Store. Just, search. I'd recommend Smart App Protector (I use its pro version which is great). Use it to lock Google Docs app.