If I drink a litre of water in one sitting, I feel queasy and unwell. This is "the illness of a living organism". I've done it before on hot days - it's not like it's hard to drink a litre, most people can do it easily. I have been poisoned by water, using that definition, but most would say that using the term that way is needlessly pedantic.

Are you aware that just like the body regulates sugar, it also regulates water? The body tries to maintain the right level of water, and it's easy to show: drink a lot. In short order, you'll be pissing a lot, to get rid of the excess water. People that have their ability to regulate water inhibited also show a lot of illnesses as a result - in terms of demographics, this can be seen in cultures where women aren't allowed to go to the toilet during the day. Sugar doesn't get magical, unique treatment in biology - water even has its own organ system that is primarily devoted to managing water content. And if you want to get socio-political about it (unsure why this means it's a poison...), we're also addicted to water and nations go to war over fresh water supplies... something that is pretty rare for corn or cane fields.

The point is that labeling sugar as a poison is being simplistic, and the picture is far more complex than that when discussing diet.