I'm happy for those who have been helped by these devices.

The FDA approval is only a revelation to the extent that the hidden truth of the extant prescription CGM market is poor data veracity combined with high catastrophic failure of the devices under manufacturer warranty in some patients.

It's difficult to know for sure the size of the patient cohort impacted here since these numbers are not made public. If the market functioned transparently, this knowledge would be of great benefit to consumers.

Given the proprietary nature of these organizations, and the fact that they spend lots of money on lobbyists and lawyers to maintain the status quo, I'm not expecting this to get better, at least in the United States. This leaves the hope that the EU or elsewhere may be more aggressive in regulation, as they have demonstrated recently around Apple and Google.

LSS: there's a ton of room for competition, cooperation, and innovation in CGM's and their slowly evolving ecosystem of software, smart phones, and smart watches, particularly in open source where hacks frequently work around the proprietary limitations in software, i.e. information devices that have little to do with telling time save for putting a date/time stamp on their event stream which is nowhere near the 5 V's of big data in volume, velocity, or veracity.

The two leaders in the space, Dexcom and Abbott both fail at a high rate with some individuals, such as me. Turns out that at the edges, adipose tissue and its interstitial fluid are a poor proxy to plasma blood glucose in some individuals. This is likely due to fluctuations in the composition of that tissue during times of fasting: exercise and sleep.

Sadly, the price of admission for my family has been high given that no one has slept normally for five years with the screeching alarms nightly at 3 AM, which are not adequately configurable. The design failure here is clearly driven by liability.

It's worth considering that the brain's default mode network (DMN) is impacted by glycemia. This has been demonstrated via an fMRI lab at Harvard via Nicolas Bolo, et al using a small cohort of diabetics.

The leap from there to what families of diabetics have known intuitively for decades may be phenomenological, but it isn't difficult.

Put simply: diabetic mood swings may not give rise to psychosis, but the mood dynamics of glycemia have been clear for almost as long: a spectrum from hypomania or nightmares induced by hypoglycemia to hyper compulsivity or depression induced by hyperglycemia.

I'm not certain that a researcher or clinician like Bolo exists to put data behind these glycemic mood associations, but speculatively, the relationship is clear to me from a subjective metacognition perspective, as someone who's been T1D for ~50 years and also has an HbA1c below the diagnostic threshold for T1D and routinely stays functional with accurate plasma BG < 50 and shows no signs of cognitive impairment accruing to these brain states after various neurology studies.

It's worth noting that hypoglycemia itself is a dynamic range, not a constant, and is frequently lower for people who have eaten or trained on the ketogenic spectrum, i.e. ultra marathon runners like Zach Bitter.

My experience has been that the feelings associated with hypoglycemia can be paradoxically awful at BG=80 and no problem at BG=40. If you've never eaten a half gallon of ice cream yourself with no signs of obesity, then you may not understand the zen state it takes to overcome this "beyond hunger" that's immediately familiar to any experienced diabetic on earth, while recognizing that that problem does not occur naturally with the disease. It's the result of insulin overdose, carbohydrate under-supply, or both.

FWIW, Microdosing carbohydrate may be key.

I believe the first use of the term in science was actually in glucagon, IIRC, i.e. the need for yet another syringe of glucagon in emergent insulin pumps that would go beyond the current crop of devices that are near autonomy, but may inadvertently overdose or underdose the patient due to the poor veracity of CGM sensors across the board and the hybrid closed loop devices which dose based on CGM which may be demonstrably inaccurate on occasion to the tune of several hundred points off high and low.

I have n-of-1 empirical evidence of this given the fact that I wore several insulin pumps for twenty five years and used multiple CGMs over that time, some concurrently. All were what we call, "shipping the prototype". Fortunately, beyond Therac 25, that was not an option in other medical device markets; certainly not those under FDA oversight.