Abbott has received a warning letter from the FDA containing a multitude of complaints related to FreeStyle Libre, the company's continuous glucose monitor (CGM) franchise.
According to the letter, dated January 23rd 2026, in October 2025, an FDA inspection of Abbott's site in Alameda, California, had "revealed that these devices are adulterated."
In particular, "the methods used in, or the facilities or controls used for, their manufacture, packing, storage, or installation are not in conformity with the current good manufacturing practice requirements."
After the inspection, the agency alleged four violations against Abbott, who responded once in November and again in December last year.
However, the FDA stated: "We reviewed your firm's December 19, 2025, response and conclude it is not adequate."
The letter claims the response addressed "Bluetooth (BLE) connectivity testing for FreeStyle Libre 2 rather than glucose accuracy performance."
The firm must "take prompt action to address any violations identified in this letter," the FDA added.
Previous allegations
The previous warning letter had levelled several claims against Abbott.
These included the failure to adequately establish and maintain procedures to ensure that the device design is correctly translated into production specifications, which included the alleged failure to establish and maintain procedures for the design transfer of the FreeStyle Libre 3.
Additionally, the agency also alleged the failure to adequately establish and maintain procedures for finished device acceptance, which should ensure that each production run, lot, or batch of finished devices meets acceptance criteria.
The letter stated that the inspection had revealed that Abbott released finished Libre integrated CGM devices without performance testing.
The third allegation the letter makes is that the inspection revealed a failure to establish statistically valid acceptance criteria and sampling plans. These are meant to ensure that only conforming finished devices reach the distribution stage.
Finally, the FDA also alleged that the inspection revealed a failure to validate an appropriate manufacturing and release control that ensures the preservation of the validated performance of some sensors, with Abbott's proposed "interim monitoring activities and proposed future testing" not ensuring that the devices can meet "validated accuracy performance requirements."
The letter has come only a few months after Abbott had issued a medical device correction for certain FreeStyle Libre 3 and Libre 3 Plus sensors in the US.
This was due to the sensors providing falsely low glucose readings. The recall was designated a Class I recall (the most serious type) by the FDA after 860 serious injuries and seven deaths.
This latest warning comes as Abbott's full-year and fourth-quarter results saw its nutrition and diagnostics units drag on sales.