ETA: after reading your SWH, I too feel that this is less a "sugar" response than perhaps a behavioral issue. And again, it may tie in with the teacher's methods. The teacher may be rewarding classwork or good behavior with treats. And your child may be reacting to NOT being given treats for basic good behavior at home.
A good way to stop tantrums is to ignore them completely. Or when they start, stop whatever fun thing is happening (the park, a little league game, McDonalds, or reading time with mom or dad) and call an immediate cease-fire to any interaction with your child. This means eye-contact, scolding, talking, teaching, yelling, or even showing frustration on your face. Then when the tantrum stops, even if it's just for a moment, you make eye contact, you say something pleasant like "I hope it's nice weather tomorrow" or "I think the spaghetti sauce that I made for dinner tastes really good" and you interact. If your son destroys property, he loses property (his own). But not with screaming and scolding - with cold common sense. "You ripped up your sister's drawing so you will lose all your crayons and books." "You threw your Batman bedspread and things from your room all over the place, so now you will have a plain blanket tonight, and I will remove all of your toys and belongings from your room. You may have a mattress on the floor and a blanket. That's all." Say it calmly and quietly. And DO IT. And then tell him how he must behave in order to earn things back. Make each punishment fit each crime. Don't tell him to go to his room and read if he has kicked and punched you when you read. Tell him to sit or lie on his plain mattress with no books and no story time at all.
Teaching and managing behavior starts at home. There will always be someone who goes against our preferences (grandma who lets them eat cookies, a babysitter who gives them too much time on the computer, a teacher who rewards with candy...) but those are just obstacles, not the root cause. I still think this teacher's methods are really weak, but it doesn't sound like she's 100% of the issue.
Original answer:
Wow. That's just so unacceptable! (On the teacher's part, not your child, I mean). This teacher is actually handing out soda and candy in class? And watching youtube? I'd be furious.
Have you gone above the teacher's head? Does the principal know that the second grade is being taught by youtube and a Party Queen? Does the school board or superintendent?
Even worse, I feel, than handing out soda is the message that the kids are getting, about school and learning. This Party Queen is potentially telling the kids that learning and education happen where party beverages are consumed, where candy rewards are the norm. Of course his behavior reflects that at home. You tell him it's time for bed, or time to feed the cat, but you don't do it with a can of Pepsi and a handful of gummy bears. You tell him that simply because it's the right thing to do. But now he knows that soda and cookies taste good, and that's how you get things done in class, so why not try it at home?
I would speak to the principal, since you've already done the proper thing and talked to the teacher directly. I'd talk to the school board. Do any other parents have similar problems?
I would also ask your son's pediatrician to write a strictly worded letter, giving doctor's orders that your son is NOT to consume any beverages at school other than milk or juice at lunch that are provided by the cafeteria, or water, etc, that you send with his lunch or snack, whatever the situation may be. And include candy in that letter, too.
Yes, I realize that this might mean that your son will be the only one in 2nd grade that doesn't get a soda or a candy treat. But his health and well-being, and that of your family and home, are more important. Try telling your son that the soda and sugar are bad for his health, and that by drinking low-fat milk, or white grape juice, or water will help him to grow strong and healthy.