This is data that you just cannot get right now via conventional means.

Your body can produce drastically different amounts of this hormone by something as simple as just being at the doctor, and your values will fluctuate wildly throughout the day.

People take their glucose readings multiple times a day and most are not doctors.

This technology will clear the way for some fantastic insight into something that at the moment is only partially understood.

Personally I read this the other way. If the data were analyzed in the cloud, then yes, very surveillancy. But, here it says the data are analyzed on the body - that's great!

Even if it's analyzed locally, it can still get sent to the cloud. If anything it's easier to do so once it's processed data.

I'd imagine this would work similarly to a continuous glucose monitor. The local device stores up to several hours of data. Your phone or other device can upload that data if it's right next to the device. The device itself has no independent ability to transmit.

Unless it works like Oculus, where you can't watch e.g. naughty 3d movies without Zuckerberg knowing about it.