The Food and Drug Administration on Wednesday issued safety message warning people to beware of smartwatches and smart rings that claim to measure blood sugar levels without pricking the skin. “The FDA has not cleared, authorized, or approved a smartwatch or smart ring that is designed to measure or estimate blood glucose values ​​independently,” the agency wrote in the release, asking consumers, patients and caregivers to stay away. from such devices.

Non-invasive blood glucose monitoring is not currently possible on any consumer device. Popular wearables like the Apple Watch and the Oura ring can instead pair with FDA-cleared wearables like the Dexcom G7, which uses needles to read your blood sugar levels. Getting a smart watch or smart ring to monitor blood sugar levels without penetrating the skin would represent a huge advance in medicine, allowing people with diabetes, for example, to stop pricking themselves every day and alerting pre-diabetics.

Both Apple and Samsung have reportedly been working on the technology for years. Last year, Bloomberg reported that Apple’s pinless monitoring is in the “proof of concept stage” and could hit the market once the company can figure out how to shrink its size. Apple has been working on the project since 2010, though it will likely be years before the technology is small enough to be built into the Apple Watch. Samsung is too study ways to incorporate the technology into the Galaxy Ring, a product the company announced recently.

Until then, be skeptical of any device that claims to do this right now. Current smartwatches and smart rings “do not directly test blood glucose levels,” the FDA wrote. If you spot a company selling a device with these claims, you can report it to the FDA through the agency’s MedWatch Voluntary Reporting Form.