A spacer for a multiple-pane insulating glazing unit, at least having a composite composed of a glass-fiber-reinforced, polymeric main body having two pane contact surfaces, which extend parallel to one another, an adhesive surface, a glazing interior surface, and an insulation film on the adhesive surface or the adhesive surface and the connecting surfaces, where the insulation film has at least one polymeric film having a thickness of 10 μm to 100 μm, at least one polymeric layer having a thickness of 5 μm to 80 μm and also a metal layer having a thickness of 10 nm to 1500 nm or a ceramic layer having a thickness of 10 nm to 1500 nm.