In Gliffy for Confluence 8.0.0 and up, you can embed diagrams externally from within your Confluence instance.
1. Navigate to the page in which your diagram currently resides
2. Hover over the diagram, and click the “Embed” button in the top diagram toolbar
3. On the screen that follows, choose the destination from the compatible services, and a link will be automatically generated. On this screen, you can also disable all links associated with this diagram