At what level of blood sugar can Bubba be at in order to "feed the curve" (raw + a tsp of First Mate MC)? Anything below 4.0mmol / 72?
nk
Not a simple answer. It depends on many things. First, where he is in the curve and whether you think he's got a ways until nadir, so still dropping. If his numbers are slowing down and he's near his nadir, you may not need to feed his curve, just feed regular LC to keep him "surfing" or hanging out at those safe numbers. Of course, ability to monitor fits into this too. If you can't monitor as well, then you might very well feed to boost him up a bit. You also don't want to feed him a lot of carbs after his nadir, as that could shorten duration and boost his numbers more than you want.
People will feed the curve if their cats like to drop fast. Fast drops can also cause bounces, so feeding slightly higher carbs might slow the drop and prevent or reduce those bounces.
Another time to use slightly higher carbs if kitty has just earned a reduction, and the depot is influencing the cycle more than you'd like. It's too soon for another reduction but you can feed higher carbs to keep him safe until that depot stops influencing the numbers.
And yet another factor is how carb sensitive the cat is, as each cat is different. I once had Neko surfing 53 for 3 hours in a row, just on a bit of freeze dried salmon treat. Middle of the night of course.

She was fairly carb sensitive, so I wouldn't feed extra carbs unless below 50, or if for some reason I couldn't monitor and didn't trust her.
Of course, Jill summarizes it better in this post:
Using Food to Manipulate the Curve