I have found that it goes up sometimes even if the item says sugar free. It's not so bad with stuff I buy at the store, but like if I go to a Starbucks type place that claims to have sugar free drinks or smoothies, etc., I usually find that my sugar jumps way up.
This green tea thing I had didn't make my sugar go up at all, and it was very refeshing. I got it from a Vegan carry out near my job - all their stuff is pretty healthy, although not necessarily OP. But this was great and the green tea was actually in almost a paste form and the guy scooped it out of a jar. And you could see little bits of it in the drink after he blended it up with the soy milk and ice.
Hmmm, now I'm thinking I might go get one, lol