[jfengel]

CGMs are amazing, and the closed loop makes the diabetics' life vastly better. They can almost pretend they have a functioning (mechanical) pancreas.

But there's more to be done. They don't measure blood insulin, but the interstitial fluid, which responds more slowly. And a new monitor takes an hour to establish its baseline, which is an hour that your closed loop isn't complete. (I gather that the newest Dexcoms take just 30 minutes.)

A version that used just a smartwatch would be amazing, especially if it really was measuring the actual blood level. But making that sure enough to be part of a closed loop is a massive, massive hurdle. It's controlling the delivery of a medicine where both overdose and underdose are dangerous, and that means extremely high levels of precision and proof.

[exfatloss]

Yea for sure. I think another major benefit would be that it wouldn't just be available for T1Ds or curious/severe T2Ds or nerds like me. Getting an Rx and paying $200/mo is a huge opt-in hurdle.

If this was on by default in every Apple watch we'd have 20 million fewer T2Ds the next week.

The problem is that the FDA is basically forbidding anything that could even remotely be "accidentally abused" by T1Ds. To even a consumer-focused fitness CGM/watch function would have to comply by the most stringent FDA regulations like medical devices marketed specifically to T1Ds, unless you somehow modify it in a way that would prevent T1Ds from "accidentally using it." I've heard you'd need to e.g. delay the feedback by 24h, which makes it pointless.