Medical Design process basically exists (oversimplifying of course) because the engineers are not the users. It's entirely possible for one person to build something that far exceeds the quality and performance of an off the shelf device simply because they care to do a good job and have constant feedback on how it works.
There's a lot to be said for scratching your own itch!
For T1Ds, you pretty much constantly have to monitor your blood glucose level. I used to use a Pebble for this, now I use an Apple Watch. The Apple Watch backgrounds the monitoring all the damn time, so I have to click multiple buttons and wait to see my blood sugar, when the number is immediately available on my phone (the watch didn’t used to be this bad). The entire point of this hardware project is eliminating that latency.
Feels like low risk unless the watch gets out of sync (but easy enough to change the code to stop the watch from showing old data if that happens).