If you make your shader completely transparent the glow will not show. Set Transparency to none, and in the Special Effects section, toggle Hide Source to On. Your glow will then appear. And don't forget to look at the shaderGlow node to tweak some glow effects.

In my case, using the Ramp Shader, i played with the Transparency ramp because i only wanted a glow on the edge of the sphere.

good luck