Good point colange but I think the purpose/concept behind the design when used for the elderly is the converse of that though; sort of.
A device like this may help the elderly with nerve regeneration/re-firing, or as you stated "motor unit recruitment" (and hence, subsequent mild muscle tone); muscle osteoprosis, and overall mobiliy especially in those with little ability to do so as is.
Regarding diabetes, Rodja nailed it but anything that gets the uber inactive "active" again (albeit, indirectly) will inarguably asssit with increased insulin sensitivity (NIDDM patients in this case) and consequently, have a positive impact on fasting and post-prandial glucose levels. That said, to what degree? Depends on a myriad of factors. LOL
If the vibration platform helps in recruiting more motor units, then it seems like it would be more effective for athletes than the older, inactive population. Especially since, as expected, the regular strength training also improved blood glucose regulation.
