Brian is correct. Your body will convert food into sugar whether you want this or not and whether you eat sugars or not.
Blood glucose levels are normally tightly controlled. Also, before you jump to the conclusion that glucose is bad, recall that glucose is the primary source of energy for your cells! You NEED glucose in your blood.

It might not be the best idea to consume a lot of sugar because of dental problems. The PET scan story is interesting, but please remember. FIRST you are made to starve so that your glucose level is quite low. In fact if the glucose level is not low enough they will not do the PET scan. Then you are give a radioactive sugar analogue. This accumulates in metabolically active tissues (i.e cancer etc) which you then see.