Do you mean the whipped cream on top? I think this is the right link to help. There are frappuccinos with and without whipped cream, and you can compare. Just click on the drink for the nutritional information.
It looks like the whipped cream adds 20–30 grams of sugar depending on the exact type of frappaccino.
Or to put it another way even with out the cream a 16oz drink still has more sugar than a can of coke (the medias universal benchmark for evil high sugar drinks).
Ah I think I’ve figured out how to get a low sugar alternative. So it seems I could order a tall (12oz) ice latte made with almond milk and ask them to blend that.
It probably depends on the brand of almond milk they use. You can get unsweetened almond milk is 0 sugar although it doesn’t really froth which is why you don’t get it in coffee shops.