<<Disclaimer: Verify this information before applying it to your situation.>>

I spoke with the Imperial sugar company this a.m.  All of their sugar -
powdered sugar, granulated and brown sugar is gluten free.  The powdered
sugar does contain corn starch to keep it from sticking together.  The
brown sugar is free from carmel coloring and contains no gluten.  All
are processed on gluten free lines with no cross contamination
possibilities.  They did tell me that last year one of their products
produced in Lousiana (not labeled Imperial) contained carmel color but
is no longer being produced with the coloring.  Therefore, all products
produced by Imperial are considered gf.  Visit their website at:
http://www.imperialholly.com/Contact_Us/index.htm
Jill/Texas