I've heard some folks insist that it does. Of course, they were in the business of selling DE. Maybe they had enough of it to really affect the ants, maybe they just wanted to help their business. I found it too expensive to spread over the fire ants. Plus, there are many different sub-species of fire ants, some products are more/less effective on them.
I've found that 5% Sevin Dust spread around the nest can kill the ants. My favorite remedy is pouring boiling water over the mound.