I have no idea what the diagnostic criteria might be, but I would suggest that it would exclude instances where there are not clinically significant impairments, which in this context would usually mean a failure to meet age related motor developmental milestones (for instance failure to develop age appropriate "pen grip" significant lateness in learning to tie shoes, and coordination of limbs development that is below chronological age....etc).
In adulthood, it seems many grow out of their difficulties. I have to say this is not the case with me. Certainly I am better than when I was as a child, but what adult is not?
I still am significantly less physically coordinated and able than my age-peers in both gross and fine motor skills. I routinely accidently injure myself, spill things and break things. I cannot even type without drumming the keyboard no matter how hard I try to type gently, nor can I safely operate a motor vehicle on public roads, or even write fluently (I can manage to draw nice printing and writing in short spurts). Further, some days I am more grossly impacted than others. On these occassions I can barely do anything without spilling, bumping, dropping, tripping, etc. Worse I find it might take me a dozen attempts to pick up something I have dropped or to complete some other mundane physical task.