Tim Cook unveils the Apple Watch in 2014. David Paul Morris/Bloomberg

In 2011, a startup called Avolonte Health set up shop in a small office park in Palo Alto, California. The company operated out of a bland, two-story building bristling with security cameras. Engineers interviewing for jobs there weren’t even told what they’d be working on. Once new hires made their way into the lab, however, they learned that they would be trying to revolutionize diabetes care.

Avolonte wasn’t just any healthcare company. It was a project of Apple Inc., and its mission came directly from Steve Jobs. Apple’s co-founder and then-chief executive officer, ill with pancreatic cancer that would take his life near the end of that year, had tasked a group of his key executives to develop a noninvasive blood sugar monitor. It would be a potentially life-changing technology for diabetics, who would no longer need to prick themselves to monitor their blood glucose. Medical device makers have tried for years to develop something like it. Even Alphabet Inc. experimented unsuccessfully with using special contact lenses to measure the glucose in tears.

Four years after the quiet arrival of Avolonte, Tim Cook stood in the same packed auditorium where his predecessor, Jobs, had unveiled the original Macintosh and introduced the Apple Watch. Cook called it the “next chapter in Apple’s story.” The new device boasted health features: a heart rate monitor, a way to measure steps taken and calories burned, and a fitness app for tracking workouts. But the original vision had been grander. The company had envisioned the watch as a tiny medical lab, featuring the Avolonte glucose monitor as a centerpiece.

Today there remains a sense – both inside Apple and in the broader world of public health – of unfulfilled potential. The company’s effort to weave health monitoring and disease prevention into its bestselling devices has yielded breakthroughs, but the strategy has also been short-circuited by philosophical disagreements, a culture of conservatism, and technological realities. Apple has scrapped or slowed work on a broad range of promising projects, frustrating some of the doctors and engineers it hired to work on them. The details, much of which have never been reported before, are based on interviews with numerous people involved in the company’s health initiatives who asked not to be identified because they weren’t authorized to discuss the work.

Even setting aside the formidable technical challenges, health care is a different beast from consumer electronics and telecommunications, two sectors that Apple has successfully disrupted but which only very rarely deal with death and disease. “The things that they’re trying to do are not easy,” said Eric Topol, a cardiologist and director of the Scripps Research Translational Institute. An Apple spokesman declined to comment, but the company has said its work remains early.

Once just a bullet point, health and fitness are now key to how Apple sells the watch. The latest model includes a thermometer to measure body temperature for fertility planning, a sensor to measure blood oxygen levels, algorithms to track sleep, and a system to perform electrocardiograms. The company has also turned the iPhone into a fitness tracker and has given it the ability to tap into hospital records. Apple has touted stories of its products saving lives by alerting users to deadly heart conditions and automatically calling emergency services for people who have hurt themselves in falls or car crashes.


Apple’s efforts have helped bring health tracking into the mainstream. It has an enticing road map for 2024, including hypertension and sleep apnea detection for the watch and hearing aid capabilities for AirPods. There are plans to turn its forthcoming Vision Pro headset into a health and fitness device, too. And work continues on a paid health coach service that uses artificial intelligence.

“Health is a world of opportunity to help people,” said Bob Mansfield, the company’s former chief of hardware engineering who helped create the company’s health and smartwatch efforts. The Apple Watch’s “ability to play a key role in health was one of the things that excited us most about building it in the first place,” he told Bloomberg. “Compared to today, the earliest technologies built in weren’t very good. It is exciting for me to see how this idea has and continues to develop.”

In Apple’s ideal future, people will need fewer single-function medical devices like blood pressure checkers and thermometers, fewer blood draws, and fewer visits to the doctor. Cook has said that improving health will prove to be his company’s “greatest contribution to mankind.” That future could be very lucrative for the company: The health and fitness tracker market is rapidly growing, with some projecting it will become a nearly $200 billion-a-year industry within a decade.

The late essayist Susan Sontag famously wrote, “Everyone who is born holds dual citizenship, in the kingdom of the well and the kingdom of the sick.” Apple, by focusing on prevention, has preferred to stay in the kingdom of the well. Its core market is what’s known in industry parlance as the “worried well,” those of us anxiously trying to decipher our body’s signals for evidence that something is wrong. That makes a certain amount of sense for a consumer electronics company. Moving into curing or even caring for diseases would entangle the company in a web of different countries’ regulatory regimes and present hard questions about business models. But taking them on might also mean more lives saved. And that is a recurring tension within the company.

“The main takeaway from their whole strategy is that they shy away from the actual care,” said Adrian Aoun, the founder and CEO of Forward, a company that runs a chain of high-tech in-person and remote clinics. Apple is building “awesome technologies,” but they’re “skating around the problem,” he said. “Health care is messy, and you have to get your hands dirty,” he said. “At some point, you have to be ready to draw blood.”

In the early 2010s, Apple began hiring health consultants, medical device experts, and sleep scientists. It hired sensor mavens from places like Medtronic Plc with expertise across every metric Apple wanted its smartwatch to handle. Avolonte was the stealthiest initiative. The group was ostensibly separate from its parent company, allowing it to source components and conduct human trials without generating publicity, according to people with knowledge of the effort.


Only Apple’s most senior executives were aware of what was taking place in the office 15 minutes from headquarters. Avolonte was not listed in any official Apple system, and employees were barred from bringing Apple apparel into the vicinity. Staffers donned badges with an Avolonte logo (an “A” crossed with an infinity symbol, a nod to the address of Apple’s old headquarters, on a private road called Infinite Loop). And when Cook would visit the office for a status update, he’d arrive in a baseball cap, pulled low to avoid detection.

A few years and hundreds of millions of dollars into the project, Avolonte researchers settled on a technology called short-wave infrared absorption spectroscopy. This technique involves shining lasers through the skin into the interstitial fluid between the blood vessels and the cells they serve. The intensity of the light’s reflection back, researchers have found, can be used to calculate the glucose concentration in the interstitial fluid and, by extension, in the bloodstream – and the only thing that has had to penetrate the body is light.

Still, Apple had a ways to go before producing a market-ready sensor. A noninvasive system needs to see through a wide range of skin tones and analyze various blood types. It would also have to work indefinitely, unlike sensor patches like the FreeStyle Libre on shelves now, which prick the skin and need to be frequently replaced. Apple’s planned system calls for the use of AI to sift the raw data and generate a prediction for when a person may become diabetic.

As Apple prepared to introduce the watch in 2014, it became clear that the glucose sensor would not make it in. Nor would the blood pressure, blood oxygen, and electrocardiogram capabilities the company was trying to develop. There were component sourcing issues, battery and reliability concerns, and the very real problem of cramming them into the tight quarters of a device that is less than 2 inches by 2 inches.

Faced with these limitations, Apple decided it made little sense to market the watch primarily as a health device. Instead, it was positioned as a bling-y tech accessory for managing incoming calls and texts, tracking fitness, and, of course, telling the time. The then-design chief, Jony Ive, legendary for helping Jobs hone Apple’s austerely luxurious aesthetic, prodded the company into offering $17,000 watch variants made from rose gold. Apple somewhat downplayed the heart rate monitor on the first version of the device because of the sensor’s initially limited performance.

Since then, Apple has worked to increase the health capabilities of the watch, believing that a fitness device could be a major new business that wouldn’t cannibalize the iPhone. The glucose monitor project has continued, in secrecy, at a cost in the tens of millions of dollars a year. As Apple reevaluated its operations when the COVID-19 pandemic hit, it decided to bring the project onto its campus. It’s now led by Apple’s Exploratory Design Group, or XDG, a secretive team in the chip design division. The work was recently taken over by one of Apple’s top Mac and iPhone chip executives, but, according to people with knowledge of the efforts, it’s still unlikely to show up in a product for at least a few years.


Other key projects were nixed during development. Apple investigated building a nutrition tracker into its Health app and looked into selling a suite of peripherals for the Apple Watch, including a bathroom scale and an Ive-designed blood pressure cuff that didn’t need to inflate. The company prototyped watch straps with sensors that gather data from the underside of the wrist and researched both a bed-mounted sleep tracker and a nightstand device with sensors to monitor users overnight before pushing the technology into the watch itself.

For a time, Apple engineers were also deeply engaged in making the watch and Health app compatible with the billions of Android devices in circulation. The move, codenamed Project Fennel, would have brought the company’s health features – and the health benefits Apple has repeatedly underlined – to many more people, especially in countries where Apple has little market share. But other business considerations prevailed: The work was nearly complete when Project Fennel was canceled, in part because the Apple Watch is a driver of iPhone sales. “If you gave up the watch to Android, you would dilute the value of the watch to the iPhone,” said someone with knowledge of the decision.

Prototypes and projects that don’t make it to market are commonplace in the tech world. However, some of those working on the new technologies have chafed at the cautious nature of Apple’s efforts. They say company engineers and doctors have long had to contend with fears from top executives that a poor medical experience with Apple could tarnish the perception of the company. “Tim and Jeff are so terrified of doing something wrong and are focused on protecting the company’s image,” one person said, referring to Cook and Chief Operating Officer Jeff Williams, who is responsible for the company’s health work. Other people with knowledge of the health team also attribute the cautiousness to privacy requirements and to the difficulty of gathering viable health data from the wrist.

The former site of Avolonte in Palo Alto. Ashlee Vance/Bloomberg

That mix of trepidation and ambition shapes some of the new features the company is rolling out. The planned addition of a blood pressure sensor to the Apple Watch next year is a pathbreaking technology. In its first iteration, however, the system is designed to just tell a user if their blood pressure is trending upward and to offer a journal for the user to jot down what was happening when hypertension occurred. To avoid potentially giving a misdiagnosis, the feature will then direct a user to talk to their doctor or check their blood pressure with a traditional cuff, which can provide exact systolic and diastolic measurements. A future version of the system is in the works with the ability to provide exact numbers – and even diagnose related conditions. But those enhancements remain far off.

The blood glucose system may operate similarly at first. During development, it’s been designed to monitor how a person’s blood sugar is trending and warn users of prediabetes, rather than offer an actual blood sugar reading. “Apple is going after nanotechnology and software,” a person involved in the work said. “That’s what we are very good at. What we’re not interested in is post-sick health care.”

The distinction between health and health care defines much of what Apple will be doing for the foreseeable future. Early considerations for the virtual health and fitness coach include the ability to generate eating, sleeping, and exercise recommendations from data collected from Apple devices, according to people with knowledge of its development. There are concepts, too, for tapping into device cameras to track and correct users’ form while they’re exercising, similar to a feature offered on Peloton Interactive Inc.’s TV-connected workout device. If all goes according to plan, AirPods by next year will be able to function as an over-the-counter hearing aid and be able to perform the hearing tests typically administered in audiologists’ offices.


Meanwhile, Apple is laying the groundwork to turn the Vision Pro headset into a health device. The company is working on new anti-anxiety and enhanced meditation features for the product and on a virtual-reality system to reinforce positive thinking and improve mental health. Apple has also been studying using the sensors in the device to scan a wearer’s eyes for cognitive health data. A headset version of Fitness+, Apple’s workout video subscription, remains on the table, with the company trying to perfect a full-body tracking system that would allow the headset to decipher a person’s leg movements during workouts. This would further put the $3,500 product in competition with Meta Platforms Inc.’s Quest, which already lets people exercise in a virtual environment.

Also on the map for 2024 is a watch-based sleep apnea detection feature. It will use sleep and breathing patterns to estimate whether someone has the condition. It will then direct users to see a physician.

Still, there are some signs that the company is exploring capabilities that would verge on treatment. Right now its pulse oximeter sensor will only show a person their blood oxygen percentage, not what the data means. The current version of the app makes this clear, telling users: “Blood Oxygen measurements are not intended for medical use.” The company is considering seeking health regulatory approval that would allow it to interpret the data for consumers. Apple also wants to expand the watch’s thermometer so it can sense a fever, not just power its fertility tracking feature. And, last year, it launched AFib History, a feature that lets people with the condition track how long they are in a state of atrial fibrillation.

Apple has explored various business models for the watch, including one inspired by a practice that had worked for the company in the past. In the early days of the iPhone, Apple sold the devices to consumers at a discount, getting wireless carriers to cover the rest. Apple got paid full value, while the carriers were able to lock in consumers to long-term contracts for phone service. With its watch, Apple explored a similar arrangement: Health insurers would cover much or all of the price of the Apple Watch, hook consumers on their insurance plans and ultimately pay out less to doctors because the Apple health features would keep customers out of the hospital. Over the past several years, Apple has reached agreements with Aetna Inc. and UnitedHealthcare, but several other insurers turned down Apple’s overtures, believing it would take too long to turn a profit on their investment.

Unlike healthcare leaders at some other technology companies, Williams is an engineering and operations expert, not a doctor. Much of Apple’s health strategy, therefore, is led by Sumbul Desai, a physician turned healthcare executive who was recruited by Williams in 2017 to come to Apple and manage its employee health clinics. Desai came from Stanford University, where she served as the associate chief medical officer and led a push into so-called digital-first primary care at the school’s healthcare system.

Apple had ambitions of building something similar. The concept, known within the company as Infinite Health, was for Apple to push into consumer medical care, building clinics across major cities and even within its retail stores, according to people with knowledge of the discussions. The clinics would feature the open spaces and clean lines of an Apple retail store and sleek equipment like the non-inflating blood-pressure cuff. Apple-employed doctors there would review data collected from the company’s devices and fill in the gaps with standardized equipment.


Some people at Apple envisioned the clinics as a way for the company to reinvent health care in the same way it revolutionized music players and phones. Apple even held acquisition talks with Crossover Health, which ran the onsite clinics where Apple employees could get care at work, as well as with the chain One Medical, which Amazon.com Inc. would buy for nearly $4 billion in 2023. “What Amazon is doing now,” said a person who worked on the project, “is what we were hoping we could do in an Apple-like way.”

Williams pitched the consumer clinics idea to Cook many years ago, but the duo ultimately landed on a compromise: taking over the infrastructure and technology of the existing Apple employee clinics. The idea was to turn a corporate perk into a kind of healthcare innovation lab and, in Silicon Valley vernacular, ask employees to eat the same dog food they were considering selling to their customers. “The thought process was if we can’t ship something good enough for our employees, no consumer will want this thing,” said a person involved in the work. “It was a bit of a dogfooding exercise.”

The dog food, however, was not great. The clinics in Silicon Valley, eventually relaunched by Desai under the name AC Wellness, provide adequate care, but they’re extremely expensive to run. “There’s no way any consumer or employer would ever pay what it takes Apple to run the clinics,” said a person involved in their creation, given the high costs of the devices, salaries, and the backend services to power the offering. “It’s probably fine for a population of young and healthy employees, but you wouldn’t want to run a Medicare Advantage plan with it,” said someone else with knowledge of the clinics. Still, the broader Infinite Health concept for consumer clinics hasn’t been completely abandoned.

Another dogfooding exercise was an app called HealthHabit, where users could chat with a care coordinator and then, if necessary, be routed to a medical professional. Doctors could answer simple questions such as, “Should I take Advil for a hurt knee?” but the service couldn’t offer much in the way of new prescriptions or diagnoses. At the peak of its internal testing, HealthHabit only had about 3,500 users, out of a population of many tens of thousands at Apple offices in Silicon Valley. “This was the first real go at how you can have a physician in the loop during health care from Apple, and it was such a failure, it killed the vision,” said a person involved in its development. Apple canceled an expansion to employees in Texas, and the app never made it to consumers. The company eventually repurposed some of the work for a new internal tool.

According to multiple people who worked on that and other health initiatives, part of the problem has been the health team’s leadership. One physician in the group, upon leaving at the end of 2019, sent a scathing email to Cook and Williams reviewed by Bloomberg that describes a workplace characterized by “authoritarian rule through intimidation and fierce retribution for not marching in line.” In addition to complaints like these, physicians have criticized executives for offering up erroneous medical information in meetings and then upbraiding colleagues who contradicted them.

At a product event in September, the company didn’t make as much noise as usual about health. It released a mental health feature for the iPhone and Apple Watch that allows a user to log how they are feeling throughout the day and a mechanism that warns users against holding their devices too close to their eyes for long periods.

In a sense, the fate of the blood glucose sensor will be a sign of how willing the company is to move beyond the worried well into the kingdom of the sick. Some involved in Apple’s health efforts don’t believe the company will leverage its future blood sugar checker on the Apple Watch as a medical device for people who already have diabetes – because of regulatory concerns and technology limitations that could create the risk of giving a patient an incorrect result.

Still, senior executives and board members at the company point out that preventing millions of people from getting diabetes in the first place is an enormous accomplishment. “The goal is not only to fix the prick problem,” said someone who has been briefed on the work by one of its leaders, “but to change the global problem of diabetes.” Apple, in other words, is still thinking big.

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