The non-prescription (in US). https://www.stelo.com works just like the Dexcom G7 (a sensor you place on back of upper arm) but it does not offer an alarm for a BG low..so it is offered only for general health monitoring, not to be used by diabetics. The difference between interstitial and capillary blood can be calibrated with a Stelo and the unit saves a 24 hour trace. You can connect to a Dexcom app or something like Apple Health and save the 2 week result, and then need to recalibrate when you change the sensor. Always, always check a low reading against a glucometer. "Compression lows" during sleep are common.
Excellent User Guides at above website. Non-invasive is still in the future.

CGM = continuous glucose monitor .. consists of a small sensor worn on the skin, often on the back of the arm but can also be placed on the lower abdomen, or the low back/upper butt cheek. It has a tiny thin needle that pierces shallowly into the tissue directly below the skin and remains in place for up to 15 days. It measures the glucose level of the fluid found in that tissue, a.k.a. "interstitial fluid". It does NOT measure blood glucose, because the tiny needle doesn't pierce into a vein or capillary. The sensor uses bluetooth technology to send readings continuously to an app on a smartphone, or similar separate device (my niece's partner is T1D; their CGM readings go simultaneously to smartphone AND insulin pump). More info about how CGMs work here .. https://my.clevelandclinic.org/heal...-monitoring-cgm

Note that this thread is about "over the counter" availability of CGMs in the USA .. previously were available only to diabetics and only by prescription. In Canada, CGMs have been available OTC (without prescription) since at least 2019 .. but of course, insurance will only cover for diabetic with prescription. They're very, very expensive!

(slaps head) I meant to say, smart watches are more suited than cell phones for health monitoring. And of course people use them for that.

An actual needle inserted under the skin? That doesn't seem very comfortable, especially if the monitor is being used by non-diabetics. Why go through constant discomfort. On a buttock?! Or even underarm or lower belly? Ouch.

I can see that it would be a useful diagnostic for a T2 diabetic, to track how their body responds to lifestyle choices throughout the day, but for how long?

I knew one very old fellow who could tolerate only brown bread and soup, and would go into a diabetic coma very easily if he ate anything, literally, than that prescribed diet. So something like this would have been useful for him. I think he went into hospital and probably died because they wouldn't tailor the diet for exactly his needs. Poor guy. But he was well up into his 90's and had a very full life.

It's not a needle, more like a thin filament. Painless to apply, don’t notice it while wearing. Video explanation:
https://www.stelo.com/en-us/how-it-works
Underarm seems best for avoiding compression lows during sleep.

I used PRE-Meal BG to determine timing of meals, adjust macros, which leads to healthy and sustainable weight loss. If you only check post-meal BG, that is limited data. I’ve been using a simple glucometer for 4 years and the fingersticks never bothered me, but these new CGMs are popular for their ease of use and information.

You don't feel the CGM filament once it's inserted unless you catch it on something. You can also put a patch over it to make it less likely to catch/pull.

My experience is that the Libre3 is not nearly as accurate as the finger stick as has been mentioned. Also if you have an older phone, the app won't work and you have to try and get a separate reader. I had an older Libre years ago and thought it was better.

For people who don't believe certain foods are bad for their blood sugars or won't finger stick or need overnight readings, the CGM's can be helpful, I think. Even if the accuracy is not as precise, they do give you the trend line.