FDA warns consumers to avoid smartwatches and rings claiming to measure blood sugar without piercing skin, saying they are unauthorized, risky, and inaccurate.

That smartwatch tracking your blood sugar could end up doing more harm than good.

The U.S. Food and Drug Administration (FDA) issued a warning against using wearable devices that measure blood glucose without piercing the skin, saying they provide inaccurate readings that could lead to “potentially fatal errors” in diabetes management.

While these smartwatches and rings are indeed noninvasive, they have been not cleared or approved, making them risky for diabetics who depend on accurate monitoring, according to the FDA.