I'm finally trying the Microcontrollers.
What you see here (L to R) is an Arduino Uno with USB Shield, a Teensy 3.1 with USB Shield and an Arduino Mega ADK. Currently the ADK setup is running with the Dexcom and the TI watch. Battery life is amazing. I have the Mega written to "wake up" every 2 minutes, get the number from the Dexcom and update the watch, so the Mega is only using full current for a couple of seconds out of every 2 minutes.
The big hurdle with the microcontrollers, is USB support. The Mega ADK comes with a single port, so I've added a USB hub. I also was working with two Arduinos using I2C, one communicates with the TI the other with the Dexcom. The problem with that configuration, is I can't save power by putting the Arduinos to sleep.
I may be able to get by with a very small battery, and have everything work for days without a recharge. The TI watch has yet to require a charge since I purchased it last year. The Metawatch needs a charge daily.
The Arduino Uno, was a failure, it can't handle the amount of data coming from the Dexcom. I'm hoping the Teensy will work. If it does, this will be almost pocket sized.
I also have on order a transmitter for the TI, that may have improved range. Might be a week or two before I see that. Also, with this device, I'll only need one USB Port, so the hub goes away.
Snowy weekend coming up, hope to at least see if the Teensy will work.