SMARTWATCH HEALTH DATA. HOW USEFUL IS IT?

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Physician anesthesiologist at Stanford at Associated Anesthesiologists Medical Group

Richard Novak, MD is a Stanford physician board certified in anesthesiology and internal medicine.Dr. Novak is an Adjunct Clinical Professor in the Department of Anesthesiology, Perioperative and Pain Medicine at Stanford University, the Medical Director at Waverley Surgery Center in Palo Alto, California, and a member of the Associated Anesthesiologists Medical Group in Palo Alto, California.
emailrjnov@yahoo.com

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Anesthesiologists observe vital sign monitors continuously in the operating room every day, and have more experience following vital sign abnormalities minute-to-minute than other physicians. Health and Human Services Secretary Robert F. Kennedy Jr. (RFK) wants everyone to wear a smartwatch, fitness tracker, or other piece of wearable health tech as part of his “Make America Healthy Again” (MAHA) agenda, so individuals can follow their own health care information on their wearable. RFK told a House subcommittee on June 25, 2025, “My vision is every American is wearing a wearable within four years. It’s a way of people taking control over their own health. They can take responsibility. They can see…what food is doing to their glucose levels, their heart rates, and a number of other metrics as they eat it.”

Monitoring vital sign information is one thing. Interpreting and acting on vital sign information is quite another. If Americans accumulate copious personal health information collected on their wearables, will this make them healthier? Where’s the data to support RFK’s claim?

A wearable such as an Apple Watch can report health data in the following areas:

Heart rate
ECG tracing
Blood oxygen
Sleep
Medications
Glucose level (with the purchase of an appropriate sensor)
Daily exercise totals/activity/calories burned
Daily caloric intake (if the wearer of the watch inputs this information)

Let’s look at each application in terms of its utility, to determine whether RFK’s call for all of us to buy and use wearables makes sense:

Heart rate. A wearable can detect and track your heart rate. Of course, you could measure your heart rate at any time without a wearable by placing a finger on your pulse at your wrist (radial artery) or at your neck (carotid artery). A wearable can tabulate your heart rate over the course of a day, but how will you use this information? Per RFK, individuals “can see…what food is doing to their glucose levels, their heart rates.” There’s no data there will be a difference in someone’s heart rate when they eat a salad versus when they eat a pepperoni pizza. Health Utility Assessment: heart rate measurement is a valuable feature. If you’re feeling sick, check your heart rate. If your heart rate is too slow, i.e. less than 50 beats per minute, a visit to a cardiologist is indicated to evaluate whether this bradycardia is harmful to your health, i.e. if you need a pacemaker. If your heart rate is too fast, i.e. sinus tachycardia persistently faster than 100 beats per minute, a visit to a doctor is also indicated.
ECG tracing. A wearable can detect your ECG rhythm and determine whether your heart is in normal sinus rhythm, or in an abnormal rhythm such as atrial fibrillation. If you’re in atrial fibrillation, an immediate visit to a medical facility/emergency room may be indicated, depending on the rate of the ventricular response. Health Utility Assessment: A valuable feature, but you’d need to suspect an arrythmia before you choose to activate this technology. In the absence of symptoms, it’s unlikely you’ll suspect or detect that you’re either in atrial fibrillation or another abnormal ECG rhythm.
Blood oxygen level. The blood oxygen level, or oxygen saturation level, is equivalent to what a pulse oximeter measures in the operating room. The pulse oximeter is a terrific monitor, and the fact that we can wear a smartwatch to measure the percentage of oxygen in our arterial blood is wonderful. To activate this measurement, you’ll need to open the app on your Apple Watch. If you have normal heart and lungs and you’re not acutely ill, it’s unlikely your oxygen saturation will be abnormal (that is, under 90 percent). If you’re short of breath, then measurement of your pulse oxygen level is a critical and significant piece of information. Health Utility Assessment: This is an extremely useful app, to be used when you’re short of breath to detect the presence and/or severity of any cardiopulmonary disease state. If your oxygen saturation is less than 90%, a visit to an Emergency Room or Urgent Care Clinic is indicated. If you’re feeling fine, the chance that this app will improve your health is minimal.
Blood pressure. Companies are developing wearables which measure blood pressure, but the technology is not yet satisfactory. Cuffless BP sensors still face obstacles in achieving clinical-grade reliability due to issues with sensor calibration, motion artifacts and placement accuracy. An Apple Watch will not measure your blood pressure. Future clinical trials are needed to validate the performance of wearable blood pressure sensors to ensure compliance with established medical standards prior to broader adoption in healthcare settings. Health Utility Assessment: This technology will be valuable if it is perfected.
Sleep. If you wear your Apple Watch to bed, it will give you a readout of your sleep patterns the following morning. The data will include the total number of hours of sleep, as well as the amount of time you are awake, in REM sleep, in Core sleep, or in Deep sleep. An Apple Watch Series 9 or later can also notify the wearer of sleep apnea disturbances. Health Utility Assessment: This is a useful app, but again only if you pay attention to the data. If your total hours of sleep are too low (i.e. less than 6 hours), it’s up to you to improve on your total amount of sleep. Many adult patients in America suffer from disordered sleep and/or insomnia. Will the Apple Watch improve your sleep? No, but it can inform you that you have a problem, so you visit a physician to attempt to improve your sleep habits and hygiene.
Medications. You can input your list of prescription medications into your smart watch, and you can look up the side effects and healthcare information regarding your medications in the PDR (Prescribers’ Digital Reference) app or website on your smartphone. Health Utility Assessment: Information on your medications is valuable, but storing this information on your wearable will not necessarily improve your health.
Glucose level (with the purchase of an appropriate sensor.) The Apple Watch does not currently offer built-in blood glucose monitoring. One can use third-party apps and devices, such as the Dexcom G7 continuous glucose monitoring (CGM) system to display glucose levels on an Apple Watch. Patients with diabetes and prediabetes benefit from a CGM wearable. These CGM wearables require a patch stuck on your upper arm. The patch usually includes a microneedle technology to sense the concentration of glucose in your interstitial fluid (not your bloodstream), and relays your glucose concentration to your smartphone or watch. Is a glucose-sensing app useful for non-diabetic Americans to “..what food is doing to their glucose levels, their heart rates, and a number of other metrics as they eat it,” as RFK recommends? No, there is no data that measuring glucose levels on non-diabetic individuals improves their health in any way. Glucose levels may transiently rise in non-diabetics after a meal. The pancreas then releases insulin to regulate the blood sugar level back to within the normal range. If a non-diabetic American knew what their glucose level was one hour after eating two Big Macs, a large order of French fries, and a chocolate shake, would that make them healthier? No. If they realized that eating two Big Macs (508 calories X 2 = 1016 calories), a large order of French fries (447 calories), and a chocolate shake (520 calories) came to a total of 1983 calories, then they could make a different decision regarding eating so much. There are no current wearable apps which accurately and noninvasively measure glucose levels. On February 21, 2024, the U.S. Food and Drug Administration (FDA) warned consumers, patients, caregivers, and health care providers of risks related to using smartwatches or smart rings that claim to measure blood glucose levels (blood sugar) without piercing the skin. “These devices are different than smartwatch applications that display data from FDA-authorized blood glucose measuring devices that pierce the skin, like continuous glucose monitoring devices (CGMs). The FDA has not authorized, cleared, or approved any smartwatch or smart ring that is intended to measure or estimate blood glucose values on its own. . . . Do not buy or use smartwatches or smart rings that claim to measure blood glucose levels.” Health Utility Assessment: For non-diabetics there is currently no data that measuring your glucose levels minute-to-minute will improve your health. “During the last years, measuring glucose has gained popularity within the sports community and successful endurance athletes have been seen with skin-mounted sensors for continuous glucose monitoring (CGM). The technique offers real-time recording of glucose concentrations in the interstitium, which is assumed to be equivalent to concentrations in the blood. Although continuous measurements of a parameter that is intimately connected to metabolism and health can seem appealing, there is no current consensus on how to interpret measurements within this context. Well-defined approaches to use glucose monitoring to improve endurance athletes’ performance and health are lacking.” The cost of purchasing CGM technology is not insignificant (the Dexcon 7 CGM system costs an estimated $45/month). RFK’s claim that glucose monitoring for all is an important goal is simply false.
Daily exercise totals/activity/calories burned. An Apple Watch, a Fitbit, or even an iPhone in your pocket will track your daily number of steps, miles walked, flights climbed, and calories burned. These are important metrics of how much exercise we do on a daily basis. A personal target to walk 10,000 steps or to walk 4 miles per day is a valuable health goal. This data can be accumulated from an Apple Watch or a Fitbit, but it’s also recorded if you keep your iPhone in your pocket all day (without any need for a wearable smartwatch). Health Utility Assessment: This is a useful app, but only if you pay attention to the data. If you’re walking a mere 0.5 miles per day and you don’t do anything to increase your exercise level, this app will do nothing to make you healthier.
Daily caloric intake. Apple Watch apps to quantitate daily caloric intake do exist, but the wearer must input the food eaten each day. (The HEALBE GoBe U smart band claims to automatically “count calories from food and drinks all by itself,” but I’m skeptical that this technology can be accurate.) Health Utility Assessment: If an individual inputs and calculates their daily caloric intake, and balances this against their daily exercise caloric burn, then they are on their way to controlling their battle against obesity.

Wearables have a place in American healthcare. When used in the contexts described above, they can be valuable. Applications for wearables will expand in future years. Big Data from wearables may someday be accumulated by healthcare systems, and the results may prove important (or they may infringe on our healthcare privacy). But wearables cost money. Their batteries need to be charged daily. Does every American need to wear one all the time? Not at this time. Should the government fund a program to ensure all Americans own and use a wearable? No.

Does every American need to pay better attention to the number of calories they eat and the number of calories that they burn off by daily exercise? Yes. There’s an epidemic of obesity in the United States. Go to any shopping center and observe the people walking around. Eating less and exercising more is the path to resolving the epidemic of obesity. A wearable can help, but pushing oneself away from the dinner table a bit quicker and going for a long walk every day is the first intervention, not buying another piece of technology to wear on your wrist while you’re watching TV and eating Doritos.