A diabetic who takes medication which may lower his blood sugar too much (insulin, gyburide or glipizide, the glitazones) should carry glucose tablets to quickly elevate the sugar level in case of a bad hypoglycemic reaction. Low blood sugar reactions can cause unconsciousness, seizures, and even death in under a few hours. High sugars take much much longer to do damage.
All diabetics should watch their carbohydrate intake. Sugar itself is no better or worse than similar amounts of potato, rice, or bread.
Yeah, it’s neither and it’s both. My brother sometimes gets up late at night to eat some cookies or fruit if his blood sugar is low. Similarly, he’ll use enough insulin for what he plans to eat, and then shouldn’t go over/under that.
He does have “emergency” glucose supplies, but AFAIK he’s never used them. I know he’s got these glucose things that look like a package of Starburst, and he’s got this syringe kit someplace with sugar in it in case he’s unconcious.
But most folks I consort with eat a few raisins or drink a little orange juice if they think their blood sugar is dipping. I eat a few almonds before I go to bed to keep my blood sugar steadier through the night.