I'm a type 1 diabetic. When a diabetic gets low blood sugar and they don't eat something they will eventually have seizures, and than eventually die as the body is starved of energy.
Shipped poultry is living on the absorbed egg yolk which will sustain them for 2-4 days generally. After that they are out of energy and will have low blood sugar. I always give my shipped poultry the sugar water mixture the first day or two to help them get some quick energy.
Birds that have low blood sugar will many times not eat which would help too, but they are physically unable to do so because the brain, and body has no energy. They get so low in energy that they just give up. I've been there.
People like to do the electrolytes which is fine too as it contains glucose. The brown sugar is an old timer remedy from before electrolytes were a thing. I've revived quite a few by making them drink and giving it time to work.
I don't know for sure, but I doubt sugar type would matter. Brown sugar seems to dissolve the best in water to me, and I probably initially read it somewhere a long time ago. You could probably use other quick sugar sources like karo syrup, molasses, or honey, but I've always used brown sugar which contains a slightly higher content of iron, calcium, and potassium, so it's kinda like an electrolyte solution.
I've always offered for the first day or two, than back to plain water. I only use it on shipped poultry. It's just what I have always done.
