As Sue says forget the sugars.......Total Carb's is important to any Diabetic. As to what is a good level, you alone will have to test to see what is good for YOU. Everybody is different in the amount that they can tolerate.
I have 'No added sugar' drinks with something like 1-2g carbs per 100 mil of the concentrate. A glass of that once diluted has a minimal amount of carbs so as far as I am concerned are pretty safe. I even have the full strength Vimto which has around 5.4g per 100 mil of concentrate, again once diluted not a lot of carbs providing I don't drink gallons of the stuff ! Some 'No added sugar' drinks contain more than I have quoted......always check.
It is more the carb content of foods that cause me problems.......