DE affects the joints of bugs/insects...and...like has been mentioned, you'll have an airborne dust problem with any most any vacuum unless it is a HEPA type.....
Here are a couple of links you might want to take a look at...
https://insects.tamu.edu/extension/publications/epubs/e-433.cfm and
http://apps.cdpr.ca.gov/schoolipm/managing_pests/74_antgrub.pdf
I use 5% Sevin dust for the rare occasion fleas decide to pester us.....
Here's a post I did several days ago, for the same problem:
As to getting fleas out of carpet, rugs, from hardwood floors, etc., get yourself 6-8 new vacuum bags...to start with & get yourself a large package of Sevin Dust (be sure the pkg. mentions fleas) & turn off your A/C & running fans, vacuum all carpets, rugs & other floor4 areas, remove the vacuum bag & discard it...either in an outside bin or take it to a garbage disposal area...DON"T LEAVE IN THE HOUSE. Next, install a new vacuum bag, sprinkle the Sevin dust around, take a stiff bristled broom and drag it through the sprinkled material (I say drag rather than broom) so as to get a good spreading without aerating the dust. Once the initial dust has settled, you can turn your A/C and/or fans back on.....
Let that set for 48 hours, then vacuum & go through the same process as above.....the 3rd, 4th, 5th & any succeeding treatments can be on 72 hour separations.....the reason for all the treatments is to break the fleas life cycles & since each flea doesn't hatch at the same time you have to attack the various hatchings.....
Pigeon keepers & keepers of fancy show chickens even dust their birds with Sevin dust, to keep fleas & mites out of their aviaries & nest boxes.....
Rabbit breeders, mink breeders, chinchilla breeders & other animal breeders, use Sevin dust in & around cages also.....
Going after the fleas is only a band-aid solution if you don't go after the carriers.....get your vet to give you oral medication for your dogs & cats or get Frontline (not the cheap knock offs) products for both & applicate them according to directions.....or.....make them outdoor animals.....