This is a waterproof Otterbox. Costs about the same as the Raspberry PI. The PI is underneath the Dexcom. Some modifications were made to the PI with a dremel! I removed the audio out and all the pin headers, to allow the battery to sit flat in the case. The Powergen battery gives about 7.5 hours.
I'm now using the Metawatch. This is the only Waterproof smart watch on the market(at this time).
I was also hoping for increased range, between the PI and the watch, but I'm not really getting that. The range is maybe a few feet greater than the TI Chronos. What I do get is an easier to use API for the watch, and the ability to make the watch buzz, for low and high alerts. That's glucose on the left, the minute the reading was taken on the right. Also, in the center I show up or down arrows for rapid rise/fall rates. The minute indicator is so I know if things aren't working.
Initially I wrote everything in C#. Then I ported it over to Linux on my laptop. In Ubuntu Linux, I was unable to communicate with the Dexcom using the driver that Linux chose. Luckily, when I tried this on the Raspberry PI, the driver that loaded there, worked fine.
Getting the Metawatch working was also a challenge. I ended up using a python script (pymw.py) that is publicly available. The C# drawing routine that I was using to generate the bmp for the display wouldn't run on the PI, so I ended up making a call out to imagemagik.
This is it for now. I'm still not thrilled with the overall size, but it works for me. I think it could be feasible to use a jail broken iPhone 5, the major hurdle would be the USB driver.