This is Optimizer, a weekly newsletter sent from Verge senior reviewer Victoria Song that dissects and discusses the latest gizmos and potions that swear they’re going to change your life. Opt in for Optimizer here.

During last week’s Apple Watch announcement, I let out a distinct “Noooo!” in the Steve Jobs Theater. Along with a new readiness metric and a redesigned Health app, Apple had just announced that later this year, it’d be introducing a new longevity feature called Health Age. 

This is a familiar concept in the wearable and health tech world. The idea is that if you put effort into your health and fitness, your physiological age could be “younger” than your chronological age. (Or older if you’re not putting in the effort.) Whoop has “Whoop age.” Oura has a “cardiovascular age” metric. My Withings scale just introduced various “longevity intelligence” features that include separate “heart age” and “vascular age” metrics. Garmin also has a “fitness age score.” At CES, I sat in front of a so-called longevity mirror that measured the blood flow in my face from a 30-second selfie to estimate my “physiological age” and my “facial skin age.” Earlier this week, I woke up and found out that my $5,000 smart mattress topper is also estimating my “biological age.”

If you ask Whoop, I’m supposedly 42. Over the past two years, Oura says my heart has been anywhere from seven years younger to 1.5 years younger than my chronological age. (It’s currently sitting at two years younger.) Withings says my vascular age is a year older than I am, while my heart is four years younger. Garmin says my fitness age is 36.5 years old. That longevity mirror? My facial skin age was apparently 26 (sunscreen, baby!), while my physiological age was 35. My very rude bed said I’m “trending older” this week at 38.7 years old. 

My actual age is 38 years old — and that’s what I’m sticking with.

I’m not trying to rain on Apple’s (or other wearable makers’) parade. Frankly, I won’t rule on Apple’s version of the feature until I can test it for myself. I bring this all up to illustrate a point about when this type of feature can be genuinely helpful — and when you should treat it with a healthy dose of skepticism. As with most metrics, it’s all in the framing.

It’s true that through a healthy diet, good sleeping habits, and regular exercise, your physiological condition might be better than that of other people who are the same age and fit within a similar demographic. Depending on how a company defines its various longevity-related age scores, your results can identify areas where you can improve. For example, my Whoop age is somewhat cursed because it heavily weights strength training workouts in the algorithm. The last time I tested Whoop, I wasn’t going super hard on lifting heavy and perhaps was a bit too into cardio. If I wanted my Whoop age to improve, lifting weights would’ve been an easy way to tilt that number in my favor.

Objectively, recalibrating my training habits to be more balanced would be a good thing for my long-term health. If you leave it exactly at that, there’s nothing wrong with this type of feature. But culturally speaking, that’s not how these “health age” scores work. 

The way I’ve seen people talk about this metric largely hews toward fluffing up your ego. If your health age is older, you probably don’t talk about it. It’s “shameful” even though, really, it’s not. That’s because culturally — at least in the West — getting old isn’t considered a good thing. If your health age is younger, it becomes something to bandy about. Apple’s vice president of health, Sumbul Desai, even says in this Instagram Reel that Health Age could be something you brag about to your friends. That explains why tech entrepreneur Bryan Johnson, famous for his quest to never die, would post this absurd take on X about how aliens would struggle to distinguish him from his teenage son, alongside a chart titled “Is Bryan Johnson More 18 or 49?” Johnson is 49; he looks a little younger, maybe, and his metrics might be comparable to someone much younger on average, but his current state is ultimately just what 49 looks like for him. 

Furthermore, your wearable-determined age is oftentimes not capturing the whole picture. You could game the Whoop Age metric to the letter, get your annual physical, and find out that your cholesterol level is through the roof. A reader once related this exact story to me. You could optimize all the controllable lifestyle health factors — diet, exercise, and sleep — like Bryan Johnson and still end up with autoimmune gastritis, as he has. Some of your health is encoded in your genetics, and while you can better the odds, your ultimate fate is not always something you can decide. We all know of someone who was healthy as a horse and died tragically young because of a freak accident. 

Personally, my various health ages have always indicated I’m moderately younger than my chronological age. But even then, that’s not an accurate picture of how I’m aging either. I’m definitely fitter now at 38 than I was at 18. As a teen, I couldn’t even run a mile nonstop, and in my 30s, I have multiple half-marathons under my belt. But my bones also snap, crackle, and pop more. I can’t pull all-nighters without caffeine like I used to, even though I eat much healthier. It doesn’t matter what potions I slather on my hair or what supplements I take; the grays keep coming. I was fitter last year, and my wearables all praised my consistent training to the point that I kept getting injured. I’m less fit this year. I’ve lost roughly 5 pounds of muscle, if smart scales are to be believed, but my metabolic biomarkers are all much, much, much healthier. To the point where earlier this week, my doctor patted me on the back and said she saw all the effort I’d put in over the past year. Yet until recently, my wearables were all convinced my health was in a death spiral. 

Health ages, I genuinely believe, were meant to be a helpful way of visualizing how small lifestyle changes can improve overall health as you age. But because they’re all defined differently and use a range of parameters, they’ve become these odd “scores” that can pass faulty judgments on how well you’re doing. I look at my hodgepodge of “ages,” and I can’t tell you what any of it truly means.

Not to get too philosophical, but time, as far as we know it, can only move forward. My rude bed is kind of right. Every week, I will be trending older because that’s simply how time works. No matter the wearable metric or magic new drug, none of us is Benjamin Buttoning our way out of that fact. 

Which brings me to my current philosophy: I am irreversibly 38, and am doing pretty alright if you ask me.

This is Optimizer, a weekly newsletter sent from Verge senior reviewer Victoria Song that dissects and discusses the latest gizmos and potions that swear they’re going to change your life. Opt in for Optimizer here.

My mom was a dramatic woman prone to overreacting. When I was a snotty teen, I told her she needed to take several chill pills. Most of the time, I was right. Back in 2004, when she was swearing in Korean and hurtling down the highway in a Honda Odyssey that had no business going 20mph over the speed limit, swerving in and out of traffic as I vomited bile into a plastic baggie, I have to admit that she was right to rush me to the emergency room.

After two days of nonstop vomiting, I thought I just had a gnarly stomach bug. Instead, I watched as doctors furrowed their brows as I failed to keep down tiny sips of water. They asked if I was diabetic. My mom said no; I was just on a ridiculous low-carb diet. Dizzy and disoriented, I was told to try peeing on a strip of paper. It changed colors. After that, things went blurry as they frantically worked to get me into a bed. I don’t remember much else, except waking up several hours and two whole IV drips later to a doctor lecturing my mom about why unsupervised diets in teens can be dangerous.

In an ill-advised attempt to lose some weight, I’d accidentally created a situation where the ketones in my blood had reached toxic levels — the official term: ketoacidosis. 

This memory was the first thing I thought of when I heard last week that Abbott had obtained FDA authorization for a new continuous glucose monitor (CGM). The Libre Duo is the first 2-in-1 CGM that measures both glucose and ketone levels. As for why diabetics would want to know about ketones, it’s the same reason why I ended up in the ER roughly 22 years ago: ketoacidosis. 

Ketoacidosis sucks, but it is somewhat common for diabetics. Diabetic ketoacidosis (DKA) occurs when there’s not enough insulin to turn blood glucose into energy. The liver then turns to burning fat, and ketones are a byproduct of that process. That’s not inherently bad, but too many ketones cause blood to become highly acidic. In diabetics, this can be an alarmingly fast process. It can also be fatal if left untreated. It’s typically a concern in Type 1 diabetics, since they don’t produce enough insulin. However, it can also occur in Type 2 diabetes — which develops over time, often due to lifestyle factors. 

“It’s actually the most common hyperglycemic emergency for people living with diabetes. It’s the leading cause of hospitalization, and it’s increased quite rapidly over the last decade,” says Marc Taub, vice president of technical operations for Abbott’s diabetes care business. “The symptoms of rising ketones are easily missed — they’re a lot like a flu or infection.”

According to Taub, the new Abbott sensor measures beta-hydroxybutyrate — a type of ketone — and is intended to function like a “check engine light.” Worn for 10 days at a time, the sensor monitors ketones in the background but will actively alert users when approaching dangerous levels, much like how CGMs do for glucose. The idea is to not only provide an actionable warning system, but to do so in a way that’s already familiar to diabetics. It uses the same app, works with smartwatches, and allows caregivers to monitor the glucose / ketone levels of loved ones — a potentially huge benefit, as DKA is a significant risk among diabetic children.

“DKA is one of the primary fears or dangers of uncontrolled or unmonitored diabetes,” says Dr. David Ahn, chief of diabetes at the Mary and Dick Allen Diabetes Center for Hoag Hospital. Ahn notes that ketone monitoring is much more common in children as part of a standard diabetes education protocol. “The overwhelming majority of adult clinicians, and even endocrinologists like myself, don’t routinely prescribe ketone strips … in a perfect world, [ketone strips] would be one of the things that we send patients home with. But in practical scenarios, it often just isn’t a top priority.” 

Ahn also notes that ketone monitoring could be helpful in two specific treatment scenarios. The first is for insulin pump users. They face a higher risk of DKA because if there’s an undetected pump issue — such as a leak or connectivity issues — it could inadvertently lead to an interrupted insulin supply and, fairly quickly, ketoacidosis. The second scenario is for diabetics taking SGLT2 inhibitors — a class of oral medications that help lower blood sugar by helping diabetics excrete excess glucose in urine. 

“SGLT2 inhibitors are quite common, but they’re primarily a Type 2 diabetes drug,” says Ahn, who says that anecdotally, clinicians have found that it helps with Type 1 diabetics too. “The problem is that our biggest clue that a patient has DKA is high blood sugar. When you’re taking an SGLT2 inhibitor, you have this uncommon pattern where your sugar might not be that high, but you can be in raging ketoacidosis.”

That, Ahn says, has been the major reason why the FDA has yet to approve SGLT2 inhibitors for Type 1 diabetics, even though it could help control blood sugar. So on paper, a 2-in-1 glucose and ketone monitor could act as a fail-safe, opening up new treatment options for Type 1 diabetics. That, combined with helping diabetic children and insulin pump users, means this tech should be a no-brainer, right?

Well, yes and no. 

CGMs are an imperfect technology. Peruse any diabetic subreddit, and you’ll see folks who — while grateful for the peace of mind CGMs can provide — have concerns about accuracy, data fatigue, and interpreting what their glucose levels mean. Glance at discussions about the Libre Duo, and you’ll find plenty of Type 1 diabetics who aren’t sold on the idea. Some diabetics claim they haven’t needed to check for ketones in over a decade. Others worry about false positives triggering disruptive alerts. (And after testing the Dexcom G7 for the past few weeks, alerts can be quite loud.) 

“I think it’s going to maybe be a rocky first year, or couple of years, but I’m also excited because I think we’re going to learn a lot. There’s so much we don’t know about ketone levels on a continuous basis,” Ahn says. “If you think about it, a ketone strip doesn’t even typically give you a number. It’s a color code of mild, moderate, and severe.” 

This is one of the clearest examples of how wearable technology can be a double-edged sword. On the one hand, the tech opens up a bigger picture of what’s going on in the human body under a wide range of previously unmeasurable scenarios. That can end up being helpful for medical discoveries and for building a greater understanding of certain conditions than spot-check tests. It’s why so many medical researchers see the potential in using wearables. However, the challenge is tuning the massive amount of continuous wearable data to identify and draw a user’s attention to the correct signals.

Abbott’s Taub says the company worked with the FDA and the clinicians to come up with ketone performance standards for the Duo. But even among the professionals, there’s still a degree of guesswork when it comes to interpreting new data.

“There was a recent consensus statement published by top experts basically saying, ‘This is our guidance on ketone monitoring.’ They set a cutoff of 3 mmol/L. But even in that article — and I’ve talked to the authors of that article — that’s our best guess as to what numbers we should start worrying about,” explains Ahn. He went on to say that factors like pregnancy, illness, fasting, and heavy exercise are all instances outside of DKA that could cause ketone levels to temporarily rise. 

“The medical community is a little anxious about understanding the signal-to-noise ratio,” Ahn says. “I think there’s going to be a lot of false positives.”

Eventually, it’s likely that the Duo sensor will follow a familiar wearable script. It’ll undoubtedly enable the medical community to learn a great deal more about ketones and DKA. The early stages will be a tad bumpy, especially since wearable tech has a complicated relationship with accuracy. For now, Taub says the Duo will require a prescription, and Abbott doesn’t have immediate plans to expand access to over-the-counter applications. But it’s not hard to see a scenario where, down the line, the Duo’s technology is marketed to a wider consumer base. 

Metabolic tech is the new wearable frontier. Health tech startups increasingly want bodily fluids to measure metabolism. GLP-1s are an ever more popular treatment. The populace is experimenting with gray market peptides. The keto diet — which gets its name from ketones and where a metabolic state of fat-burning called ketosis is the ultimate goal — has been popular for close to 20 years now. You don’t have to be a genius to see how various consumer wearable companies could look at the Duo and see a new data field riddled with dollar signs. From there, it’s not hard to see wellness influencers flattening a genuinely helpful technology as the “secret hack” the medical institution “doesn’t want you to know.”

This is, after all, what happened with CGMs. 

The Duo makes me reflect on some periods in my life where I was less wise. I ended up in the ER with ketoacidosis, a rare feat for non-diabetics, because I was a stressed-out teen lured into a fad diet by glossy magazines and celebrities wasting away in low-rise jeans. Would some version of the Duo have helped prevent that? The self-quantifying nerd in me says yes. The wearable expert in me suspects that, given my previous experiences with CGMs, I personally may have avoided an ER trip and instead spiraled into data obsession and then fatigue. 

None of this is to say that the Libre Duo is bad. Wearable tech is always a neutral tool with the potential to enable a lot of good — it just requires thought and discernment to be used in a truly healthy way. The thing is, the vast majority of people in their day-to-day lives won’t need to monitor for ketoacidosis. When medical science adds another data set to our lives, it’s important we ask why; that we understand what it actually tells us, and not just what we hope it says, or what we hope it can do for us.

Correction, September 2nd, 2026: A previous version of this article misspelled Marc Taub’s name. The ketone alert function has also been clarified.

This is Optimizer, a weekly newsletter sent from Verge senior reviewer Victoria Song that dissects and discusses the latest gizmos and potions that swear they’re going to change your life. Opt in for Optimizer here.

Oura’s getting sued.

A recently filed class-action complaint against the smart ring maker alleges that the company has duped customers by claiming it can accurately track different sleep stages. A smart ring can’t possibly do that, the suit says, because the Oura Ring doesn’t directly measure your brain waves. Instead, Oura uses AI models to take advantage of “desperate consumers who struggle with their sleep … by selling faulty AI-based inference as reliable science.” The suit frames Oura Ring as no more accurate than a “coin flip.” 

When I first saw this lawsuit, I laughed it off. It assumes that Oura users aren’t smart enough to know the ring on their finger can’t measure what’s going on inside their skull. 

All wearable devices collect data and then use algorithms — or machine learning AI — to make inferences about various health metrics. As a noninvasive tool, no wearable directly measures anything except motion. The benefit is that noninvasive wearables allow for passive, all-day monitoring. Responsible companies then validate those metrics against clinical, gold-standard methods to create consumer-oriented screening tools and monitoring metrics. It’s not always the most accurate, but even broadly accurate data has improved — and even saved — many lives.

Again, I laughed because, surely, no one would take this lawsuit seriously. Wearables might not measure brain waves, but other measurable physiological changes happen during various sleep stages too. Your heart rate slows, your body temperature rises and falls, and your body paralyzes your muscles during REM so you don’t act out your dreams. But then I logged on and saw the discourse. Several outlets had covered the lawsuit. It was popping up on social media and in Reddit forums. Some commenters used it as a way to say, “Aha! I knew these devices were off!” Others said this discrepancy was illustrative of everything wrong with this current era of optimized obsession. A few wearable nerds reacted the same way I did. Oura published its own rebuttal to the suit, linking to several validation studies in peer-reviewed journals for its sleep tracking algorithm, alongside a supportive op-ed from a sleep researcher.

As a wearables expert, I find the lawsuit’s logic to be lacking, but it did help me identify the real problem here. We still struggle to remember what the point of wearable tech is and how to use it properly. Case in point: Accuracy is a bit of a red herring in this conversation because that’s not always the point of a wearable.

All wearables vary when it comes to sleep tracking accuracy. In general, independent third-party reviews find they are pretty good at detecting when you fall asleep and wake up. Sleep stages are where things get murky, as each company uses a proprietary algorithm to estimate if you’re in REM, deep, or light sleep based on motion, temperature, and heart rate sensors. They can get things wrong for several reasons, ranging from sleep position to battery levels. 

Wearables are meant to be used as a tool to track long-term trends. Chances are, if you’re sleeping poorly, you can logically pinpoint a reason why without a gadget. Maybe you drank too much before bed. Perhaps your cat yowls at 5:30AM for breakfast. But, say you’re not an observant person, and there is no obvious reason. The point of a consumer sleep tracker is to get a bird’s-eye view of your sleep pattern. It’s a means of helping you reflect on the lifestyle reasons why your sleep might be doodoo. And in the absence of a reasonable explanation, it’s a tool to help facilitate conversations with a doctor. It does not and will not ever fully replace clinical polysomnography or sleep clinics.

Because wearables rely on indirect methods of estimating health metrics, there is always a possibility that your results might be wackadoodle wonky here and there. The point is the device should be consistent enough to give you a good idea when something is really off. A “check engine light,” if you will. Sometimes, you’ll get false alarms. But the point is you’ve checked in and are more aware.

There’s some nuance here. If I’m generous, this lawsuit could be a good-faith attempt to force health tech companies to be much more precise with their marketing claims. Sometimes less scrupulous companies do embed blatant science-washing into their marketing. I agree that sometimes health tech companies can present features in a misleading way that can cause material harm. This, in my opinion, just doesn’t happen to be one of them. (Again, Oura is almost overly aggressive in showing the receipts of its peer-reviewed scientific research.) 

You could argue that more companies ought to include easily accessible educational blurbs. That’s especially true now given the dangerously blurred line between wellness and medical tech. It’d be nice if more wearable companies explained that the closer a feature hews toward medical tech or diagnostic capabilities, the more accuracy matters. If it’s simply to monitor trends, eh. It matters more that a device is consistently inaccurate by the same amount because measuring trends is the most important thing. That’s why certain screening features require FDA clearance and wellness features do not. The Pixel Watch 5’s new breathing emergency feature? Accuracy matters quite a bit there because the watch will call emergency services on your behalf if it detects you may have stopped breathing for an extended period of time. Sleep stages, however, are a clear example of a wellness feature meant to help you monitor long-term trends and how lifestyle choices may impact your perceived sleep quality. If it’s not the most accurate, well, the stakes are much lower.

But to say that wearables companies don’t extensively plaster their UI with educational information about how certain metrics ought to be interpreted and how they’re derived is also untrue. These companies include warnings and disclosures within apps that explain that certain features are wellness and not diagnostic. In Oura’s case, any curious consumer could google “Is the Oura Ring accurate for sleep stages?” and get a succinct AI overview that reads “The Oura Ring is reasonably accurate for tracking general sleep duration and identifying when you fall asleep or wake up, but its breakdown of specific sleep stages is only an estimate.” That’s then followed by dozens of links to studies comparing the sleep accuracy of various trackers and explanatory articles by tech journalists doing the exact same thing. 

So why does a class action lawsuit like this even exist? Perhaps the fault is with tech journalists like myself if we preemptively dismiss an opportunity to reinforce context or fail to provide the appropriate analysis. Maybe we’re not writing explainers in the most accessible way. I hesitate to blame consumers. This is a genuinely confusing space, but then again, I find most people are smarter than they’re given credit for. Even so, there’s also only so much educational material that can be provided if a user opts not to read any of it. Ultimately, it’s on companies to make sure consumers understand the limitations of their products. For all the lawsuit harps on accuracy, its most compelling argument is that sweeping marketing claims may lead to consumers misunderstanding how a product ought to be used.

In any case, the takeaway from this lawsuit shouldn’t be that Oura — or wearables at large — are scam products with no value. If that were true, Apple wouldn’t introduce its latest smartwatch every year with real-life testimonials of how it saves lives. Researchers wouldn’t have flocked to wearables to study illness detection during the covid-19 pandemic. To me, this lawsuit is sort of its own “check engine light.” If people are truly duped and do not understand how these features work, it’s an opportunity to recalibrate the conversation.