Unlikely. The FAA permits continuance of a flight by a diabetic (to a landing point) with a class III medical and waiver if testing under 300 mg/dl.
Passing out? Not really, but having levels constantly that elevated is slowly eating away your insides. Falling asleep? This would depend on the individual. Some may, some may not. If an individual is passing out and/or unexpectedly falling asleep he/she needs to get a full health exam asap to rule out life threatening disease/s caused by and/or influenced by uncontrolled diabetes. Good luck -