Cereals seem to wander from one category to another more than any food in my various lists.  One reason for that might be that formulas for the cereals often vary from country to country and the bulk of testing has been in Australia. Here are some  breakfast cereals that tend to have a lower GI number, but are not on the green list.

Bran Buds

Bran Chex

Raisin Bran

Life

Mini Wheats

Muesli

Nutri Grain

Shredded Wheat

Most of the rest are on the red light list, including:

Cornflakes

Cheerios

Corn Chex

Cream of Wheat

etc.

Many cereals are listed by name in my reference books, so I will be happy to check out your favorite for you.   And by the way — don’t dump sugar on your cereal!  Use another natural sweetener if you have to have it sweeter.