Avoid form re-submission clicking on back button

I have a form. On submit of a button, it inserts a record into the db. If I go back in my browser and refresh the page it's resubmitting it causing all sorts of issues as you can imagine. How do I ensure that the user can't refresh the previous page and the state of that page does another automatic submit on refresh like this?
 
I'm not using ViewState. I actually have it disabled in the page directive
No, Response.Redirect does NOT solve this problem. The user can still go back with the browser's back button and refresh at the point where they submitted and it will still run the button's event sending the data downstream to my DL insert