glTF 2.0 specification only supports exporting PBR materials based on a metallic-roughness model.
Material exportsupport for Blender's glTF exporter only works for Cycles render materials at the moment.
And even then it requires a specific node setup to be used, as mentioned in the user documentation, through the use of a Node Group designed for this purpose. The node group is available for download from the repository.
Future updates to supportFor future versions, EEVEE material node treestree support is planned, using the Principled BSDF Shader, but unavailabeit is unavailable at the moment.