Carbocisteine

Measure bloods before you take it then 1 and 2 hours after and see the effects?
Obviously don't eat or drink anything part from water in that period and in the hours beforehand.

@dvj Here is a reference that may help. I'm sorry if you can't access it, but I don't know of a non-professional access.

http://www.medicines.org.uk/emc/medicine/12500/PIL/Mucodyne+Syrup

Essentially, carbocysteine contains sucrose, in syrup at least. I think that this will affect diabetes to some extent or another.

Probably, the capsules have much less, if any, sucrose in them. Hope this helps.

Edit:
http://www.medicines.org.uk/emc/medicine/3872/PIL/Mucodyne+375mg+Capsules
Capsules don't appear to have sucrose in them.

I take them and they have no effect on my BS