Yep, it is the sugar!! check his/her gums if they are a good bright pink the sugar level is up, if they start to look whitish and dull they are low on sugar.
Our Spec (that's her name) was hpoglycemic as a 10 week old she was given suryup maybe a 1/4 oz if she got too much she would go yorkie crazy for an hour or so. She is normally very layed back. we only gave it to her a few times! then she was fine!
Spec's Dad