Should You Check Your Blood Glucose With a Smartwatch? No, and Here's Why Not
Key takeaways:
Blood glucose smartwatches and smart rings are not an accurate way for people living with diabetes to measure their blood glucose (sugar). The FDA hasn’t approved, cleared, or authorized any of these devices yet.
The accuracy of blood glucose smartwatches varies. While some devices have promising accuracy results in studies, it’s still early on in the research process.
If you have diabetes, it’s recommended to use an FDA-cleared glucometer or continuous glucose monitor (CGM) to measure your glucose levels. These devices have all been evaluated by the FDA for safety and effectiveness.
Many people living with diabetes check their glucose (sugar) on a daily basis. This is essential for knowing if medications are working or dosage adjustments need to be made. Having accurate glucose measurements is also important for knowing if your glucose is too high (hyperglycemia) or too low (hypoglycemia).
But checking your glucose by poking your finger with a lancet can be painful. And continuous glucose monitors (CGMs) can be uncomfortable for some people. So scientists have been looking for a noninvasive way of checking blood glucose for years.
While the technology isn’t quite there yet, that hasn’t stopped some companies from claiming they've found the solution. Recently, there’s been a rise in companies selling wearable devices, such as smartwatches, that claim to monitor blood glucose. But buyers beware: These devices aren’t FDA cleared or accurate.
Are blood glucose smartwatches and rings accurate?
The accuracy of blood glucose smartwatches or smart rings can’t be guaranteed at this time. In fact, the FDA put out a safety notice in February 2024 warning people living with diabetes not to use them. In that announcement, the agency said, “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.”
Blood glucose smartwatches vary widely in how accurate they are. But to be considered for FDA clearance, over-the-counter (OTC) glucose monitors need to meet certain accuracy requirements:
At least 95% of all readings must be within 15% of readings from a blood glucose monitor that’s currently FDA cleared and known to be accurate.
At least 99% of all readings must be within 20% of readings from a blood glucose monitor that’s currently FDA cleared and known to be accurate.
Some companies have shared the results of their research with blood glucose smartwatches. In one study, a device called InCheck only met accuracy requirements about 18% of the time it was used. That means it was inaccurate more than 80% of the time.
Another blood glucose smartwatch had better results. In the clinical study, the device was accurate about 84% of the time. However, this study was only conducted with 23 people, and only about half of them had diabetes. The study also used a definition of accuracy that’s different from the FDA’s. So the results of this study can’t be used to determine accuracy for the general population.
The blood glucose smartwatch GWave seems to have had some of the most promising results so far. In early studies, it was considered accurate 98% of the time. Similar to the device above, the study was small (involving 43 people) and none of the participants had diabetes. So we don’t know if the results would be the same for people living with diabetes. But researchers are planning to conduct larger studies in people with Type 1 and Type 2 diabetes to see if GWave has similar levels of accuracy.
Devices on the horizon: Blood glucose smartwatches aren’t the only devices being studied for diabetes benefits. Read more about the diabetes devices that are being researched.
Getting accurate readings: Getting accurate glucose readings is key when it comes to managing diabetes. Read about the best and most accurate ways to monitor your glucose levels at home.
Glucose monitoring with prediabetes: Some people with prediabetes are choosing to wear continuous glucose monitors to track their glucose levels. Find out what the research says.
How do blood glucose smartwatches work?
Companies making blood glucose smartwatches are using different technologies in their devices, including:
Electrochemical technology: These devices measure the amount of glucose in different bodily fluids, such as sweat or tears. This is the type of technology being explored in smart contact lenses. It’s important to note that this technology doesn’t technically measure blood glucose, since it isn’t taking readings of blood.
Optical technology: These devices shine certain light wavelengths, such as infrared light, on the skin. These wavelengths penetrate through skin and bodily fluids, such as plasma. But glucose molecules absorb them. The devices then sense the amount of wavelengths that were absorbed to determine the amount of glucose.
Electromagnetic technology: These devices provide a small amount of stimulation to the skin, tissues, and blood vessels around the smartwatch’s sensor. Glucose has a unique reaction compared to other fluids and tissues. The device looks for this reaction to measure the amount of glucose.
Microwave technology: These devices send a small amount of microwaves through the skin and blood vessels. Different substances inside the body either absorb or reflect these microwaves. The device determines the amount of blood glucose present based on how much is reflected back.
Are there FDA-cleared glucose monitoring devices?
Yes, there are several FDA-cleared glucose monitors. These devices can be split into two main categories: glucometers and CGMs.
With glucometers, you use a lancet to prick a finger and apply a drop of blood to a test strip. The device then measures the amount of glucose in your blood. These are available to purchase with or without a prescription. Examples of FDA-cleared glucometers include:
CGMs are a device you wear on either your abdomen or the back of your arm. They measure the amount of glucose in the fluid beneath your skin. Most CGMs require a prescription from a licensed healthcare professional. Examples of FDA-cleared CGMs include:
Dexcom Stelo (the first CGM to be cleared for OTC purchase)
What is the most effective way to monitor blood glucose levels?
Both glucometers and CGMs are effective tools for monitoring glucose levels. Typically, people choose which device to use based on their healthcare professional’s advice, their personal preference, their insurance coverage, and the cost. Research indicates that CGMs are better than glucometers at helping people stay within their target glucose range. And they can help lower the number of hypoglycemia episodes people experience.
But because CGMs don’t measure blood glucose, there’s a small lag time with the results. This means that it may take a few extra minutes for a CGM to notify you about blood glucose changes. So you will still need to have a glucometer at home, even if you’re using a CGM on a daily basis.
If you feel symptoms of hypoglycemia, such as shaking or sweating, you should double check your glucose with a glucometer, even if your CGM gives a “normal” glucose reading.
The bottom line
It’s not recommended to use blood glucose (sugar) smartwatches or smart rings at this time. None of these devices have been FDA cleared, and their accuracy levels vary. While some of the research is promising, blood glucose smartwatches are still in early development.
If you’re living with diabetes, you should use an FDA-cleared glucometer or continuous glucose monitor (CGM). These devices have been thoroughly evaluated for their safety and accuracy.
Why trust our experts?
References
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Hirsch, I. B., et al. (2023). 130-lb: GWave—A novel noninvasive glucose blood monitoring radio wave-based technology. Diabetes.
LifeScan Europe GmbH. (n.d.). OneTouch Ultra 2 blood glucose monitoring system: User guide.
Mondal, H., et al. (2024). Accuracy of a non-invasive home glucose monitor for measurement of blood glucose. Indian Journal of Endocrinology and Metabolism.
Roche Diabetes Care, Inc. (2023). Accu-Chek Guide blood glucose monitoring system: User’s manual for single patient use only blood glucose meter.
Roy, S. (2024). US FDA warns against using smartwatches to measure blood glucose. Reuters.
U.S. Food and Drug Administration. (2020). Self-monitoring blood glucose test systems for over-the-counter use: Guidance for industry and Food and Drug Administration staff.
U.S. Food and Drug Administration. (2024). Do not use smartwatches or smart rings to measure blood glucose levels: FDA safety communication.
Wu, J., et al. (2023). A new generation of sensors for non-invasive blood glucose monitoring. American Journal of Translational Research.
