Is there a grounding requirement for this dishwasher?

Yes, the dishwasher must be grounded. The dishwasher is equipped with a cord having an equipment-grounding conductor and a grounding plug that must be plugged into an appropriate outlet installed and grounded in accordance with all local codes and ordinances. (Page 3) Do not modify the plug provided; if it won't fit, have a qualified electrician install a proper outlet.