Google Universal Analytics is a blessing in our opinion. It allows so many new possibilities. Moreover, the good news is that the Google Analytics API team has already updated the API to let us query custom dimensions and custom metrics you have set in your Google Universal Analytics setup.
In other words, you can create custom dimensions and metrics and then create reports or dashboards on this new data. It’s as simple as using any other metric or dimensions from the Advanced Editor:
One think to remember: If your Google Analytics profile is not a Universal Analytics one then choosing custom metrics or dimension will throw an error. Only Universal Analytics profile can report on custom metrics and dimensions.
Some good reading on Google Universal Analytics: