Resident Diabetic Here
The best thing for low blood sugar is straight sugar, or something close. Dog kibble, cheese, bread, takes a while to break down into sugar in the blood. Your best bests are corn syrop, maple syrop, granular sugar. These items turn to sugar in the blood right away.
Your brain needs sugar the same way it needs oxygene, so if your blood sugars are low, you get doppey and funny things start to happen if it goes really low, because your brain shuts parts of itself off to conserve energy.
Have the vet confirm that it isn't anything else first of course, but hypoglycemia is easy to manage.