A pattern of gas and bloating may be an indication that a tumor is growing, especially if it worsens or is accompanied by bleeding. While the formation of a tumor may not be enough to cause a total obstruction, the increasing pressure placed on the colon walls can cause distress and even cramping in the upper intestinal tract.
The more general term glucose syrup is often used synonymously with corn syrup, since glucose syrup is in the United States most commonly made from corn starch.
High fructose corn syrup contains fructose. Regular corn syrup is nearly all glucose. So the answer to the OP's question is: none, really, except that you can make glucose syrup from other sources of starch as well. To my knowledge, corn syrup can have fructose in it, and even other kinds of longer sugars.