We normally use corn syrup when needing quick sugars at home, in a deep low at night for instance. But we have discovered this to be very difficult to find in Europe. It is also messy if you travel all the time: what if it leaks in the car…
So we just puchased glucose powder (GI 100) that we found online:
We are using it by dissolving it in a cup with a straw and letting our son drink from it. He does not even wake up.