Why the iWatch won't measure glucose levels

A multitude of reasons why the iWatch will not monitor user glucose levels.

It's widely believed that Apple sometime in 2014 or soon thereafter will introduce what many are calling the "iWatch," a wearable device capable of tracking all sorts of interesting biometric data.

Over the past few months, Apple has hired a formidable team of biomedical experts with deep experience in medical sensor technologies. Notably, many of the folks now working for Apple have done impressive and groundbreaking work in the realm of continuous glucose monitoring (CGM).

Many news outlets, as a result, have reported that Apple's rumored iWatch may be able to non-invasively measure a user's glucose levels. Such a device would be a godsend for diabetics who often have to monitor their blood glucose levels multiple times a day, either by drawing blood from their finger or through an implanted sensor paired with an external monitoring device.

The rumors swirling around the iWatch have grown so unwieldly, the expectations so beyond the realms of modern science, that many are already pegging the iWatch as a revolutionary medical device that will leapfrog competing devices like the Fitbit and the Nike FuelBand by offering unprecedented medical sensor technologies to the masses. Just last week, the San Francisco Chronicle published a report claiming that Apple is researching sensor technologies capable of predicting heart attacks "by studying the sound blood makes at it flows through arteries."

It's time to jump back to reality.

Here, we will specifically focus on the the idea that Apple's iWatch will be able to measure a user's glucose levels.

Recently, well-connected 9to5Mac blogger Mark Gurman reiterated that the iWatch will, in fact, be able to monitor glucose levels.

Our knowledge is reliant upon what Apple is programming the Healthbook app to be capable of and based on the company’s recent hires. Our sources today have reiterated that Healthbook is planned to be able to read glucose-related data...

Given Gurman's impressive track record for accurately breaking Apple news, many outlets have similarly made the leap from "Apple is hiring folks with expertise in continuous glucose monitoring" to "the iWatch will monitor user glucose levels."

A deeper examination of the issue, however, strongly suggests otherwise.

Non-invasive CGM is an incredibly complex problem that presents a number of challenging medical and technological hurdles. Indeed, medical device companies have been trying to solve this problem for decades, with no real success to speak of.

Apple and C8 Medisensors

Over the past few months, Apple has hired a number of scientists and engineers from C8 Medisensors, an innovative California-based company (now defunct) that was singularly focused on developing a non-invasive CGM device called the HG1-c.

To really gauge the feasibility of an iWatch that monitors glucose levels, it's helpful to take a deeper look at the HG1-c's capabilities and limitations. Indeed, doing so brings to light a number of daunting challenges that would arise in bringing the technology to market, let alone embedding it in a wristwatch.

Employing a technology called Raman spectroscopy, the HG1-c was able to measure users' glucose levels by transmitting a pulse of light through the skin, thereby causing glucose molecules to vibrate. An optic sensor then detected the light reflected off of these molecules, whereupon the device analyzed the resulting "fingerprint" and returned a glucose reading.

Issue 1: Size

The HG1-c was a wearable device intended to be worn across the abdomen. It was impressively compact for the technology it housed, but certainly not small enough to embed inside of a wristwatch. Bear in mind that it also came with a separate battery pack. Together, the device weighed in at 5 ounces, about an ounce heavier than the iPhone 4.

Issue 2: Sunlight

Size aside, the HG1-c carried a number of other limitations that would prevent it from being wrist ready.

On account of the technology it used, the HG1-c was extremely sensitive to sunlight and needed to be cloaked in as much darkness as possible to truly be effective. This, of course, is an obvious deal-breaker for any device meant to be worn on the wrist.

I was able to chat with Charles Martin, a former C8 employee who helped work on the HG1-c's firmware, who expounded on this in greater detail.

Mr. Martin explains:

Yes, the camera sensor had to be shrouded in darkness to function. You have to understand that Raman Spectroscopy is looking for a very faint signal emitted by the glucose molecules. A rough analogy: try to pick out someone's voice in a noisy room. The sunlight was this kind of noise that the camera sensor was not calibrated against. They did try to implement algorithms to discount measurements against sunlight anomalies, but some of the anomaly criteria these algorithms were supposed to detect, overlapped. This made things hard to verify and test on the device.

Also bear in mind that the camera sensor's performance was affected by variables as innocuous as a user's body hair and skin color, limitations that certainly don't bode well for a wearable device designed for the masses.

Issue 3: Physical Activity

Further, the HG1-c wasn't designed to be worn while partaking in physical activity because the sensor, in order to work accurately, had to be nestled up directly against the skin. And to help provide better optics for the sensor, users of the device were supposed to apply a layer of gel between their skin and the device.

Again, this limitation is an absolute deal breaker for a mass consumer product intended for the wrist.

Issue 4: Battery Life

Another issue that would seemingly preclude C8's technology from working in a wristwatch, at last for now, pertains to battery life. The HG1-c, which came with a separate battery pack, featured a battery life of 30 hours when taking glucose measurements every 15 minutes and a battery life of 20 hours when taking glucose measurements every 10 minutes.

With reports that Apple is already struggling to attain battery life of  "at least 4-5 days between charges," it stands to reason that battery-hungry CGM functionality isn't in the cards.

Achieving the impossible in a few months

So if we're to believe that an iWatch capable of non-invasive CGM is on the horizon, we're forced to make a number of lofty assumptions about Apple's ability to miniaturize the technology, vastly improve its battery life, and address all of the other aforementioned issues that make the device ill-suited as a mass market consumer product. Also keep in mind that the HG1-c was only tested on and intended for individuals over 18 and non-pregnant women.

What's more, many of Apple's biomedical and medical hires only joined the company in the last few months. Developing a bonafide medical breakthrough device in such a compressed timeframe runs against all notions of plausibility.

C8's CGM technology was impressive, but much work remained

For the sake of discussion, let's assume that the iWatch only measured glucose levels at the directive of the user. In other words, let's envision a non-continuous and user-initiated glucose monitor.

Even in this scenario, a multitude of serious issues remain.

To say that monitoring glucose levels via non-invasive means is an extremely complex and challenging task is an understatement on the grandest scale.

A multitude of companies over the course of many decades have tried and failed to tackle this very problem even as it pertains to invasive glucose monitoring, spending untold hundreds of millions of dollars in the process.

That said, C8's own device, which, again, relied upon Raman spectroscopy, showed much promise. The device even attained CE Mark Approval in Europe in October of 2012.

Nonetheless, the technology still had a long way to go before becoming a viable product.

On this topic, I was able to chat with C8 Medisensor CTO Rudy Hofmeister, who explained to me that while the HG1-c device was a technological feat, it was nowhere ready to being where it needed to be for a consumer device.

The HG1-c was sort of like a dancing bear; that it worked as well as it did was an absolute miracle, but it was nowhere near where it needed to be in order to be a viable medical product, and certainly not a consumer medical product where the bar is even higher.

There's a big difference between performance and efficacy. The device certainly had a level of performance that was statistically significant; it was good sometimes, random sometimes, but not anywhere good enough to be used as a diagnostic or monitoring device for a disease state.

When I inquired about the device receiving CE Mark Approval, Hofmeister explained that this approval was for an early version of the device that wasn't even manufacturable.

The CE Mark Approval allows you to sell, but it doesn't really cover efficacy. So while you can meet the device's claims, those claims can be so watered down that the product has no value.

While Hofmeister left C8 about a year before operations came to a halt, he remained abreast of what was going on at the company, as the talented folks working there were part of the team he helped assemble.

When I inquired as to how fast the C8 team was making improvements to the device before the company ran out of funding, Hofmeister explained:

All avenues to increase efficacy were being pursued, but any improvements attained were incremental, and none that would have led to the level of improvement that was needed.

What about a different approach for non-invasive CGM?

Might it be possible for Apple's team to employ a strategy other than Raman spectroscopy? Of course, but as you'll read below, no other non-invasive CGM approach - and there have been many - has ever borne fruit.

Fact: Non-invasive glucose monitoring has never been cracked

Underscoring the difficulty, frustration, and complexity associated with non-invasive glucose monitoring, John L. Smith, a leading expert on non-invasive glucose measuring technologies, wrote a book on the pursuit in 2007, updating it a few years later in 2013.

Smith's seminal book covers, in exhaustive detail, the vast number of companies (including C8) that have experimented with an extensive array of technologies and strategies in what ultimately remains a difficult puzzle that has never seen a marketable solution.

And in those seven years, I’m sad to say that no technology has yet reached the marketplace, or for that matter, been reliably reported as actually succeeding in laboratory or clinical testing. I have personally looked at perhaps another two dozen technologies (but can’t discuss many of these newer ones, due to confidentiality agreements), been intrigued by a few and disappointed in most others. Some new companies have joined the quest, and many others have reached the end of their participation.

The 2013 version of the book concludes:

As in the attempts detailed here, the horizon will continue to be clouded by spurious correlation, incomplete understanding of the sources of error, lack of rigorous evaluation of results and wishful interpretation of data. Unlike the cure for cancer, where partial success has been achieved in many areas, this one still seeks a breakthrough. It is hoped that the attempts detailed here will help to prevent others from repeating past mistakes and premature announcements, but a rational assessment would suggest that many more lie ahead.

In short, measuring glucose levels via non-invasive means has never been proven to successfully work in any product to hit the market. Solving any problem that lies at the intersection of medicine and technology is ridiculously tough. Doing so with a wearable mass-consumer mobile device only adds many more layers of complexity.

To believe that Apple, with a team that was mostly assembled in mid-2013 and onwards, will soon be able to crack this nut is patently absurd.

Apple would prefer to steer clear of FDA approval and Medical Audits

Even if we hypothetically assume that Apple and it's impressive all-star team of scientists and engineers can successfully pull off the impossible, miniaturize the device, address a number of usability issues, and improve upon its efficacy in a significant and groundbreaking way, such a device would still require FDA approval and a whole gamut of oversight that Apple isn't accustomed to.

What's more, securing FDA approval would entail extensive and careful clinical trials, with an approval process that could last as long as 18 months. In essence, entering the world of medical devices would require Apple to jump through hoops it traditionally takes pains to avoid.

On this topic, I was able to get in touch with a former C8 employee (who wished to remain anonymous) who explained some of the inherent regulatory hurdles associated with developing medical devices:

Any company that wants to sell a medical device must adhere to a regulated auditing process. The C8 product was probably as non-intrusive of a device as you can get. It was not categorized as an "implantable" device. At worst, a patient would be exposed to a laser light source (no stronger than a typical laser pointer).

C8 had to follow all sorts of procedures to ensure it would successfully pass an ISO 13485:2003 audit. For example, engineers couldn't file bugs with the existing bug-tracking tool, because the bugs were fair game for an auditor. This process was very time-consuming...

I don't think Apple is the type of company that would be comfortable working through an full medical device audit process. I don't think it would fit within the company's technology culture either (having worked there for a time).

An iWatch that measured other biometric data while steering clear of glucose measurements would undeniably fly through the watchful eyes of the FDA much more quickly.

Apple doesn't rush out new features before they're ready for prime time

Apple's success is rooted in its ability to deliver incredibly polished products that do a few things extraordinarily well. Apple's laser-like focus is why iOS didn't receive copy-and-paste functionality until iOS 3 and multitasking support until iOS 4.

So even if we assume that CGM is on Apple's iWatch roadmap, the notion that this feature will appear in the first iteration of the device is highly improbable. Simply because Apple hired an impressive team of biomedical and sensor technology experts doesn't mean the first iteration of the iWatch will be a magical, all-knowing sensor device.

Apple's initial efforts to develop an in-house mapping solution provides an illustrative example.

Apple first began putting together its internal mapping team in July of 2009 when it acquired a geo-mapping company called Placebase. And yet, Apple's standalone Maps app wasn't released until September 2012, a full three years later. What's more, many of the innovative features that made Placebase's mapping technology so unique have yet to re-appear in iOS.

That said, Apple's hiring spree of sensor experts shouldn't reflexively be construed to mean that the iWatch will monitor a myriad of health vitals out of the gate. Apple is a remarkably patient company, and again, keep in mind that many of Apple's biomedical and medical sensor hires have barely been at the company for six months.

Remember the backlash over Apple Maps? Now imagine how amplified that would be if Apple released a faulty device purporting to measure a serious health vital like glucose levels. Apple wouldn't even consider such a feature unless it was supremely confident that the technology worked flawlessly.

Apple's MO is simple - it methodically adds features to its products, slowly but surely improving its product line with each successive release. So while it stands to reason that Apple has a lot of  brilliant folks working on incredibly innovative sensor technologies, there's no strong evidence to suggest, or historic evidence that would have us reasonably conclude, that the initial version of the iWatch will be an advanced sensor supermachine.

Keeping iWatch expectations realistic

As a result, I think there's a lot of merit in MobiHealthnews writer Brian Dolan's assertion that the iWatch's "technological capabilities will be simpler than rumors have indicated."

As is Apple's style, expect it to measure a number of health-realted variables exceptionally well as opposed to measuring every conceivable vital sign under the sun. Indeed, Dolan's own sources relayed that Apple's recent hires, at least for now, are there to "ensure that the health sensing capabilities of the device" are accurate.

Former C8 CTO Rudy Hofmeister concurs on this point, arguing that any wearable device Apple releases will likely focus on "general health and fitness" rather than medical vitals.

So can we expect the iWatch to measure glucose levels? Don't bet on it.

Addressing rumors of Apple's alleged pursuit of non-invasive CGM, John L. Smith writes:

The participation of funding by big companies with no experience in glucose monitoring is sometimes pejoratively called “dumb money.” In the same way that inventors can become enamored by the prospect of helping people with diabetes (and coincidentally “cashing in” on the result), companies like GE and Motorola have made what turned out to be unwise investments in this area. Apple and Samsung, and possibly Google might be on the same trail, trying to create a watch that measures glucose noninvasively. 

One way to see who else is interested in noninvasive glucose is to see where the technical principals go after a company shuts down. An Apple-watching blog, “9 to 5 Mac” reports that Apple hired several experts in the field of non-invasive blood monitoring sensors from C8 MediSensors, and also hired employees who had worked at Senseonics and InLight Solutions. Time will tell if this turns out to be a fruitful pursuit for them.

Wearable technologies down the road

The technological and usability advancements seen from the original iPhone to what we have now with the iPhone 5s are nothing short of astounding. This, of course, goes back to Apple's penchant for slow, careful, and measured improvements.

So while the iWatch at first glance may not be the medical marvel some are understandably hoping for, what's truly exciting is that Apple, according to a bevy of circumstantial evidence, is seemingly focused on a brand new product category.

Indeed, Apple's interest in wearables is hardly a well-kept secret. Tim Cook last year told Kara Swisher and Walt Mossberg that wearable technologies is a profoundly interesting space "ripe for exploration." Cook also added that the "whole sensor field is going to explode. It's a little all over the place right now. With the arc of time, it will become clearer."

Coupled with Apple's  formidable team of biomedical engineers and medical sensor experts, the iWatch may prove to be the first step in what will one day, but not at first, be a revolutionary device.

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