> I've worked in this space for 5 years now, and this is not news to any of us.

The reason it's your comment I'm replying to is because you indicate you actually worked in this field.

Whenever these discussions surrounding noninvasive monitoring of blood solute concentrations come up I keep wondering why anyone is surprised taking a hard route is hard, and why there seems little attention to seeking easier routes of noninvasive optical sensing.

Please do shoot my comment if it is nonsensical, so that I can stop caring next time I read such a discussion, but I would like a mechanistic explanation why the lips wouldn't be easier.

From an a priori perspective, it would certainly be desirable to have any type of noninvasive monitoring in the form factor of a watch. There is nothing wrong with dreams or hope. Yet to me it sounds like a dream was interpreted too literally: starting from some hypothetical dreamer exclaiming "imagine testing concentration X or Y, but noninvasively! sure wearing a device would may come with some inconveniences, but if the advantages outweigh the inconveniences, it would find a niche" and "after all people have been wearing watches too".

An idea that started as an analogy: just like a personal wearable watch had advantages compared to an immobile pendulum clock, perhaps we can devise the analogous personal wearable device that performs the duties of some large inconvenient measuring setup, workflow, discipline,....

I can't shake the feeling that the analogy has been taken too literally, as if the original dream insists the blood glucose meter has to be integrated into the watch and located on the same or similar place on the body...

Blood is red.

Lips are red.

The color of the lips is the color of the blood.

Acknowledging the inconvenience of mounting a device or perhaps an optical fiber to your lips, it may constitute a more tractable milestone.

What is the reason all the 'failed' startups avoid the lips and make life hard on themselves by choosing to do spectroscopy (in the widest sense: plain, Raman, ...) through the highly variable noisy medium of skin (different pigmentations by genetics, different pigmentations by varying exposure to sun within an identical individual, different states of skin like sweating, the intinsic noise incurred by imaging through a robustly thick layer of skin, scattering like mist, ...).

It almost looks like attempting an artificially troubling tour de fource, akin to painting a masterpiece... with your toes. I think its possible eventually, fundamentally speaking, but it doesn't sound like a wise choice to make, at least not initially.

(I wrote failed in quotes, because in reality after bankruptcy IP is transferred, experience was gained by employees, some of which end up at different companies in the same space, others end up in new disciplines where they gain a new applicable insight that nobody previously connected to blood glucose monitoring, etc...)

Then there's the social issue of the first iterations of the tools potentially working better for less pigmented skin...

> It's probably not impossible, but we'll literally be able to use stem cells to regrow human pancreases ...

I have some serious question marks surrounding the near-term viability of stem cell regrown organs.

As an unethical thought experiment consider freshly born twins, and removing their pancreas and putting each in a chamber where you would otherwise grow the artificial pancreas. How fast would you notice harmful levels of sugar purely from observation of the kept-alive pancreas? (without cheating and using knowledge of healthy blood sugar levels). If it would take many many experiments or very long durations to detect these problems (for glucose or otherwise), then one doesn't really have the engineering confidence of how long it would last, what the side effects are, ... i.e. blanket statements that stem cell derived organs will arrive earlier than affordable democratized noninvasive sensing could be true, could be false, but isn't proven by a blanket statement. The burden of proof doesn't lay with the reader.

> ... and straight-up cure people of diabetes before this tech becomes a reality. (We're much further along that path.)

Which type of diabetes?

Type 1:

The root of the problem is an unsuitable autoimmune response, during V(D)J the immune system rolls the dice to construct a generator of randomly chosen but from then on specific antibody. Due to natural selection library of segments for V(D)J recombination has a strong bias for resulting in antibodies that match foreign pathogens and potentially endogenous cancers while simultaneously also having a strong bias for not matching normal endogenous or symbiotic features. So usually nothing goes wrong.

We all carry a different but similar library of segments for V(D)J, so our immune systems display slightly different statistics for expressing antibodies.

Imagine an individual has the flu and its immune system ramps up the production rate of new generators of antibodies, each generator corresponding with a randomly chosen but from then on fixed type of antibody, usually safe but not guaranteed. Perhaps this individual has bad luck and besides generating suitable antibodes for the flu, it has also generated a low probability antibody that happens to attack the pancreas. Over time the pancreas starts to degrade and fail. The person now has type 1 diabetes. The pancreas damage is a symptom, not the cause.

Even if you grow a new pancreas, and replace the damaged one with the freshly grown one, the immune system cells generating the regrettably bad antibodies are not filtered out of the body, so after a while the type 1 diabetes will recur! Your proposal does not straight-up cure diabetes type 1

(how hard or easy does it sound to locate and filter the specific immune system cells that result in the autoimmune disease without also removing those that represent your acquired immunity of diseases the individual was exposed to throughout life? if such a thing were easy, curing HIV would be easy by simple filtration of every last HIV genome from a human body, so it does not sound that easy at all)