Send GCE memory related metrics log to Datadog

I want to monitor the memory-related metrics (such as gcp.gce.instance.memory.balloon.ram_used) from my VM in GCE with Datadog. I can done that with Metrics Explorer in GCP but I cannot found the same metrics in Datadog (I have installed the GCP integration for Datadog). How do we send memory related metrics/log from GCP to Datadog? Many thanks before