Several of the seed catalogs have sugar beet seeds, and yes they grow much larger than the regular red beets we usually grow.
A long time ago, I knew a lady who grew them in her garden - they were larger not as red. When she made pickled beets, she would use half sugar beets, and half regular red beets. The sugar beets would take on the red color of the red beets - and because of the sugar content of the sugar beets, she did not add any sugar to the recipe.