DISAPPOINTING: FDA warns against using some smartwatches, rings to check blood glucose levels. “Smartwatches and rings that don’t pierce the skin are unreliable when it comes to reporting blood glucose levels, the U.S. Food and Drug Administration announced Wednesday. An FDA news release warns consumers and caregivers that smartwatches and rings that don’t pierce the skin might cause errors in managing diabetes and taking the correct dosages for various medications.”