Apple sauce

Picked apples yesterday and cooked and sauced them today after my eye appointment. I still don't know if there is more sugar in sweet apples than in sour apples. My apples are so sour that I need to add sugar to make them palatable. However, when I made a small batch of sauce from sweet apples from the store, I didn't add sugar. Do the sour apples have sugar that you just cannot taste, and if so am I making them doubly sugar filled (and thus worse from my diabetic body)? Also, my cat is weird.