UPDATE 2-US FDA warns against using smartwatches to measure blood glucose

(Adds details in paragraphs 4-8)

Feb 21 (Reuters) - The U.S. Food and Drug Administration warned consumers on Wednesday against using smartwatches or smart rings that claim to measure blood glucose levels without piercing the skin, regardless of manufacturer or brand.

The health regulator said it was working to ensure that manufacturers, distributors and sellers do not illegally market unauthorized gadgets that claim to measure blood glucose levels.

The devices are different from smartwatch applications that display data from FDA-authorized blood glucose measuring devices that puncture the skin, the regulator said.

The agency said it had not authorized, cleared, or approved any smartwatch or smart ring intended to measure or estimate blood glucose values on its own, nor evaluated their safety or effectiveness.

Such devices are manufactured by dozens of companies and sold under multiple brand names. Their makers often claim the gadgets can measure blood glucose levels without requiring users to prick their skin.

Inaccurate blood glucose readings can lead to errors in diabetes management, including taking the wrong dose of insulin or other medications that rapidly lower sugar levels, the FDA said. (Reporting by Sriparna Roy in Bengaluru; Editing by Shailesh Kuber and Pooja Desai)