apple watch support is awesome!

I agree with other reviewers that the iPhone notification takes up too much real estate. Just the value and the direction arrow would be enough here; the graph is not needed here.
I agree that the Apple Watch Complication should be the value and the direction arrow.
Here is a suggestion to Apple Watch users: Open the Apple Watch app on your iPhone. Go to General >Wake Screen and under On Wrist Raise select Resume Last Activity. That way if you open the Dexcom watch app, it will show the Dexcom app up every time you raise your wrist to look at your watch. And it does show the time! I wish the time were in a larger font.

DrScience about Dexcom G5 Mobile