Quick Answer
Granulated Sugar does not use the same grams-to-cups value as every other ingredient. Using a practical US cup reference, 200 grams of granulated sugar is about 1 cup.
That means 100 grams of granulated sugar is about 0.5 cups, while 200 grams is about 1 cups.
Granulated sugar packs relatively consistently, making it one of the more reliable cup-to-gram conversions among common ingredients.