I've made great progress with finding what to call in the Dexcom DLL's. 7 lines of code and I can get an XML document with everything on the receiver in it. This works great from Windows.
Now the hard part. I've figured out how to parse the raw serial data coming out of the Dex. This should allow me to port this over to Linux without needing the Dexcom DLL's. A rainy weekend is forecast, so I'll be trying to communicate with the Dex from the Raspberry PI. I've already confirmed the PI will talk to the TI Watch without issue.
Now that I'm getting close, I'm getting greedy. The TI Watch will work perfectly for my hazardous duty requirements, but it only has a transmit range of 10 feet or so. The Dexcom will go to 20 feet. I think I might have to look into the MetaWatch, water resistant and capable of greater distance with bluetooth.
I'm trying to avoid having to network with a Smart Phone though. I don't want to have to pay for Hotspot features, nor do I want to be dependent on cell phone access.