As a Type I Diabetic, I've used many continuous glucose monitoring (CGM) systems over the years. For the uninitiated, these systems traditionally consist of a small adhesive sensor which injects into your abdomen, a re-usable transmitter that attaches to the sensor, and a bluetooth enabled receiver device.

Very recently a CGM company called Dexcom released their G5 Mobile system which has one extremely freeing innovation: the receiver software can run on your iPhone, obviating the need for carrying an extra pager-sized device 24/7. It sounds like a small detail but believe me having one fewer device to carry, charge, and not drop in the toilet (true story) has been wonderfully liberating.

There is one thing though. As an iOS developer it drove me crazy that the Dexcom G5 Mobile app didn't offer an Apple Watch watch-face complication. Dexcom went 99% of the way to the holy grail of CGM only to drop the ball on the 1 yard line. I imagined being able to see my blood sugar in less than a second by simply raising my wrist. I was so close.

So I did what any efficiency obsessed diabetic iOS programmer would do. I launched Xcode and started hacking. The fact that the Dexcom Share feature sends your blood sugar data to a web server allowed me to write a simple client that downloads this data and keeps your watch in sync. My blood sugar data was already accessible on the cloud. The only real challenge was keeping the values updated while not running afoul of the processing time limits Apple imposes on third party watch apps.