You need to control your light source. A tweak here and there should
do it. You can try dulling spray, but I suspect it won't work too well
because it will dull the glass.
With a circular polarizer you should be able to dial in each shot pretty quickly without moving objects or lights. Won't work handheld, but for different stationary camera positions it should do it.
I'm not surprised. I've shot many scenes with aquariums, large
picture windows, mirrors and actors wearing glasses - all things
that create glare. A little tweak or two with the lighting and
the glare goes away.