I have trained with several people with disabilities. None of them wanted to be treated differently from the rest. We, as teachers, did not want to treat them differently. So they passed the same tests as the rest.
But do let reason dictate things: Of course, we had to adapt some tests. If you do not have a right arm, it is impossible for you to have your right arm grabbed. If you are blind, it is impossible to avoid an attack that is not a grab.
If the students requires breaks (insulin, prosthetic falls off, or just MS being too painful) then of course, you should allow it. In the same way that an on call medic (or whatnot) during a grading should be able to rush to their cell phone.
Mental disabilities need to be taken into account as well. For me, dyspraxia was one of the hardest one to deal with. But getting that same test others and passing it meant a lot to the practitioners even if they took a little longer to get there. It require a lot of change of how the techniques were taught: reinforcing good behaviour as opposed to pointing out what is wrong. Mentally handicapped people can be hard work -- mainly because we are not generally used to dealing with them, again how you teach must change not what you teach or how you grade them.
I guess the answer boils down to "How can a disabled person do the same tests or as close as it is feasible as everyone else?". Mostly, this becomes self evident once you think about it that way.