“It appears to only have a little glucose.”
From your own damn source!:
“While HFCS is comprised of approximately 45 percent glucose and 55 percent fructose (the exact percentage of fructose can vary depending on the product), plain corn syrup is simply glucose...”
It would the appear that Karo is not pure corn syrup, which Karo at least has vanilla added.
It is possible it has maltose and perhaps other sugars based on glucose, but I can’t seem to find such information.