If I thought I was going to get this kind of grilling I would make a mental list of difficult diabetic questions to ask as a pre-emptive strike that would make a simple memory task irrelevant. As Corporal Jones used to say,"They don't like it up em!"
Heres one for the "keep the brain active" club.
What is the next letter in the following sequence. OTTFFSSEN.
Took a while but got it eventually.......Im 78......Brain I think is about 25.