The Week in Blood Pressure & Wearables — September 18-24, 2026
By Yair Lurie, Founder and CEO, Cardiowell. Published September 25, 2026.
A smart ring started reporting blood pressure this week. In the same week, a primary care physician reminded clinicians that current guidelines say cuffless readings shouldn't drive diagnosis or treatment, and a law firm laid out how the FDA went from a warning letter to a closeout on consumer blood pressure features. That's this week's deep dive.
Also this week: more than 44,000 comments on Medicare's proposed remote monitoring rules, new ACCESS Model tracks for 2027, and a large English study showing how many adults with high blood pressure are still undiagnosed.
Deep dive: blood pressure on a smart ring, and what FDA clearance still means
What Circular launched
In mid-September, Circular added blood pressure estimation to the Circular Ring 2, according to Android Headlines.
Here is how it works, based on that report. The ring captures an ECG and an optical (PPG) signal at the same time. From the two, it calculates pulse wave transit time: how long the pulse from each heartbeat takes to reach the finger. In stiffer, higher-pressure arteries, the pulse travels faster. The app converts that timing into a systolic and diastolic estimate in about 60 seconds.
Two details matter. First, the user has to calibrate it by entering three readings from a regular cuff, and Circular recommends recalibrating with a cuff every month. Second, Circular says the feature is meant to help users track trends, not for diagnosis or treatment decisions. The coverage I reviewed mentions no FDA clearance for the feature, and no published accuracy data.
So this is a cuffless, calibration-based estimate. That puts it in a different category from a device like the Huawei Watch D3, which Men's Health UK described this week as a "medical-grade" monitor. The Watch D3 inflates a small cuff built into the strap and measures with the oscillometric method, the same principle as a standard arm cuff.
Why this is legal as a wellness feature now
In July 2025, FDA sent Whoop a warning letter over its Blood Pressure Insights feature. At the time, the agency said blood pressure measurement is inherently tied to diagnosing hypertension.
ArentFox Schiff's review this week walks through what happened next. On January 6, 2026, FDA issued revised General Wellness guidance. On June 17, 2026, it sent Whoop a closeout letter saying it wouldn't enforce device requirements on the modified feature.
Under the revised guidance, a noninvasive product that estimates blood pressure can qualify as a general wellness product, per Covington's summary. The conditions are strict. The product can't reference a disease or diagnostic threshold, can't claim clinical equivalence or "medical-grade" status, and can't give treatment guidance. Values that mimic clinical ones need validation.
ArentFox's read is that FDA now looks at the whole product experience: labeling, screen design, notifications, even how the subscription is packaged. Color-coded zones that look like clinical cutoffs draw scrutiny. A continuous color gradient passed.
What the guideline says
The clinical side hasn't moved. In a Patient Care Online interview published September 21, Pamela Kushner, MD, pointed to the 2025 AHA/ACC hypertension guideline: cuffless devices should not be used for diagnosis, medication titration, or clinical management of hypertension, because no clinical validation tools exist for them yet.
Her practical advice was to have patients bring their home devices to the office and compare them against calibrated equipment. In a companion segment, she tied poor measurement technique and clinical inertia directly to the country's blood pressure control gap.
My view as a founder who has been through 510(k)
Both of these can be true at once. A ring can be a legitimate wellness product, and its number still shouldn't change a prescription.
The problem starts when the number leaves the app. Patients will screenshot a ring reading and bring it to a primary care visit. Someone on the care team then has to decide what it means. Right now that person has no validation standard to lean on.
Companies that take blood pressure monitors through FDA 510(k) clearance must show it was substantially equivalent to a legally marketed predicate device. For a blood pressure monitor, that means clinical validation against reference measurements under a recognized protocol, plus labeling that matches exactly what the evidence supports. The claims come after the evidence. It's slow and expensive, and that's why a clinician can act on the reading.
A wellness feature skips that step by design. There's another detail: a ring calibrated with three home cuff readings starts from whatever error that home cuff already has. If the cuff was never validated, or the patient measured with the arm hanging at their side, the ring inherits the problem. Then it drifts until next month's recalibration.
In remote monitoring, that matters. A reading that feeds a clinical workflow has to come from a device the clinician can defend. Otherwise, we have corrupt data in the chart.
I'm optimistic about where this goes. Continuous blood pressure from a wearable is one of the most useful things this field could deliver, especially at night, when we rarely measure blood pressure. Pulse transit time is real physiology, and work on validation standards for cuffless devices is ongoing. I hope FDA and the guideline writers land on a clear validation path soon, so a ring number can earn its way into care the same way a cuff did.
Until then, my suggestion for clinics is simple: treat ring and watch estimates as a reason to take a proper cuff reading. Treat validated cuff readings as the basis for decisions.
Devices & Wearables
Apple Watch Series 12 adds a readiness score, and Eric Topol questions the metrics under it
Apple's new watches take heart rate every five seconds and measure heart rate variability (HRV) as often as every five minutes, feeding a new daily readiness score, per MacRumors.
The same week, Eric Topol argued that wearable HRV and readiness scores have real gaps. Wearables measure pulse rate variability from optical sensors, which isn't always interchangeable with the ECG-based HRV used in outcome studies. Readiness algorithms are proprietary, change without notice, and haven't been validated against health outcomes. He also noted that validation studies mostly use small groups of healthy adults.
This is the same measurement question as the deep dive, just with a different sample size.
Biolinq Shine gets FDA 510(k) clearance for over-the-counter use
Biolinq announced 510(k) clearance for OTC use of Shine, a needle-free glucose sensor for adults 22 and older who don't use insulin. It uses microsensors just below the skin surface and shows glucose status through a color-coded LED on the patch. It isn't intended for insulin dosing decisions. The product first received De Novo classification in 2025.
For anyone following cardio-kidney-metabolic care, this is another sensor that will produce data clinics will be asked to look at.
Policy & Regulation
Medicare's proposed remote monitoring rules drew more than 44,000 comments
The CY 2027 Physician Fee Schedule proposed rule, released in July, would change how Medicare pays for remote physiologic monitoring (RPM) and remote therapeutic monitoring (RTM). The comment period closed September 14.
Becker's explains the most contested piece: clinical staff providing monitoring services would have to be employed directly by the billing practice, ending payment for services furnished by contracted third-party vendors. If finalized, it takes effect January 1, 2027.
Epstein Becker Green's comments, summarized this week, opposed five proposals: the direct-employment requirement, limits to established patients, a required initiating visit for all patients, a device revaluation that would price blood pressure cuffs the same way as therapeutic platforms, and new monthly G-codes that bundle all service components. The firm counted more than 44,000 comments on regulations.gov.
The final rule usually comes in early November. For small practices that rely on outside staff to run monitoring programs, this is the rule to watch.
CMS adds heart failure, COPD, substance use, and tobacco tracks to the ACCESS Model
CMS announced on September 15 that the ACCESS Model will add tracks for heart failure, COPD, substance use disorders, tobacco cessation, and extended musculoskeletal support, starting spring 2027.
The original tracks, live since July 1, 2026, include early cardio-kidney-metabolic conditions such as hypertension. Payment is tied to measured outcomes against each patient's baseline, per Foley Hoag's summary. CMS reports 160 participating organizations, and Medicare Advantage enrollees aren't eligible. Cardiowell is one participant, with Cardiowell 360 in Colorado and soon coming to Ohio.
CMS is tightening fee-for-service monitoring rules while expanding a model that pays for results.
DEA's telemedicine special registration rule is in final review
The DEA sent its final telemedicine special registration rule to the White House Office of Information and Regulatory Affairs on August 25, Telehealth.org reports. It creates three registrations for prescribing controlled substances without an in-person visit. The current flexibilities expire December 31, 2026, and final action is expected in November, which leaves practices only weeks to adjust.
Clinical & Research
59% of adults with high blood pressure in a 1.4 million-person English study were undiagnosed
Researchers at Oxford Population Health analyzed clinic blood pressure readings from 1.4 million adults in Our Future Health, published in BMJ Public Health. Thirty-seven percent had hypertension. Of those, 59% were undiagnosed and untreated. Among people already on blood pressure medication, half still weren't controlled.
Lead author Wenyu Liu said the current approach to detecting and treating high blood pressure is "not fit for purpose," as The Guardian reported. The data is from England, but the pattern of low detection and incomplete control will be familiar to anyone running a US hypertension program.
A 51-trial analysis finds blood pressure treatment helps across every level of risk
An individual participant data analysis of 51 randomized trials and 357,440 patients found a consistent relative reduction in first cardiovascular events regardless of baseline risk, HCPLive reports. Absolute benefit rose with predicted risk. Investigator Kazem Rahimi argued that risk, more than the blood pressure number alone, should drive treatment decisions.
A SPRINT analysis links a 120 mmHg target to nearly 40% slower brain small vessel disease
A post hoc analysis of the SPRINT trial in eClinicalMedicine found that targeting systolic pressure of 120 mmHg instead of 140 mmHg slowed progression of cerebral small vessel disease by nearly 40%, according to UT Health San Antonio. Larger drops in pressure were associated with larger reductions in progression.
Alnylam's twice-yearly zilebesiran is enrolling 11,000 patients in its outcomes trial
Alnylam and Roche's ZENITH phase 3 trial is enrolling about 11,000 high-risk patients in 35 countries to test whether zilebesiran, an RNA interference therapy dosed twice a year, reduces major cardiovascular events, per MarketBeat via Yahoo Finance. A twice-yearly drug would change the adherence problem in hypertension, and it would make reliable home readings between doses more important.
Also worth a glance
Chlorthalidone recall. Inventia Healthcare recalled more than 13,500 bottles of chlorthalidone 25 mg for failed dissolution testing, a Class II recall and the second from the same manufacturer since June, Hoodline reports.
Why nighttime blood pressure may not dip. A University of Waterloo computer modeling study suggests a timing mismatch in how the kidneys handle salt can prevent the normal 10-20% overnight drop, per the university. It's a computer model and needs confirmation in patients. Still, it's another reason to pay attention to nighttime readings.
The thread this week
Every story this week came back to the same question: which numbers can a clinician act on?
A ring can estimate blood pressure legally as a wellness feature. The guideline says don't treat on it. England found most people with hypertension have never had a reading that counted. Medicare is deciding who gets paid to review home readings, and ACCESS is paying for results measured from them.
Better sensors are coming, and I think that's good news. The work for the next few years is building the validation, workflows, and payment rules that make those readings trustworthy.
References
Circular Ring 2 Can Now Measure Your Blood Pressure, and It Only Takes 60 Seconds. Android Headlines.
Huawei's New Smartwatch Puts a Medical-Grade Blood Pressure Monitor on Your Wrist. Men's Health UK.
Not FDA's Whoop-ing Boy: How a Warning Letter Became a Wellness Playbook. ArentFox Schiff.
FDA Issues Revised Guidance on General Wellness Products. Covington & Burling.
Cuffless Blood Pressure Devices Fall Short of Clinical Standards. Patient Care Online.
Clinical Inertia and Poor Measurement Technique Undermine BP Control. Patient Care Online.
Hands-On With the Apple Watch Series 12. MacRumors.
The Big Holes in Wearable Heart Rate Variability And Readiness Scores. Ground Truths (Eric Topol).
Biolinq Shine Receives FDA 510(k) Clearance for Over-the-Counter Use. GlobeNewswire.
CMS' Proposed Remote Patient Monitoring Ban, Explained. Becker's Hospital Review.
Remote Monitoring Services Under the 2027 PFS Proposed Rule: Epstein Becker Green Submits Comments to CMS. Epstein Becker Green.
CMS Adds Medicare Options to Help People Manage Substance Use Disorder, Heart Failure, and Other Common Chronic Conditions. Centers for Medicare & Medicaid Services.
CMS Expands the ACCESS Model: New Tracks for Heart Failure, COPD, Substance Use Disorders, Tobacco Cessation, and Extended MSK Support. Foley Hoag via Mondaq.
DEA Telemedicine Special Registration Rule Enters Final Review. Telehealth.org.
Two-Thirds of Adults With High Blood Pressure Do Not Know They Have It. University of Oxford.
Millions in England Unaware They Have 'Silent Killer' Condition, Research Reveals. The Guardian.
Blood Pressure Treatment Shows Consistent Benefit Across Cardiovascular Risk Spectrum. HCPLive.
UT San Antonio Study Finds Lowering Blood Pressure Benefits Brain Health. UT Health San Antonio.
Alnylam's Zilebesiran Targets Twice-Yearly Blood Pressure Control in ZENITH Trial. MarketBeat via Yahoo Finance.
Chlorthalidone Recall 2026: 13,500 Bottles Pulled by FDA. Hoodline.
What Your Overnight Blood Pressure Can Reveal About Your Health. University of Waterloo.