Just out of curiosity does anyone feel that they become less able to perform mental tasks when their blood sugar is high?
Yes, definitely. When my working day starts to go pear shaped (but I'm not hypO,) I generally find that I'm hyPER.
I'm type 1 and able to correct with insulin, but if I'm waaaaay high I generally finding myself having to draw a line under that day and retreat - blood like syrup = it's too thick for brain to work - that's how I see it.
I know that doesn't sound very scientific, but that's how it feels.