Merlin has been on and off different antibiotics for dental, cold, chronic sinusitis, etc. over this past year. I recently found out that AB does contain sugar and you can request sugar free. His last AB was Azrithomycin (which I got from a compound) for his chronic sinusitis and it normally comes with sugar. You have to ask your vet to indicate in the script "sugar-free." Also, for liquid AB, you can get it flavored. I usually get it flavored with chicken and/or vanilla butternut (which several of my cats love). I was told by the compound that neither of those flavors have sugar in it. They also have tuna flavoring but I don't get that one.
I also had the office/vet put in Merlin's file in big red letters; No Convenia and No Metacam. Fortunately, I found out that his vet does not use either one.