WARNING LETTER
Abbott Diabetes Care, Inc.
MARCS-CMS 722046 —
January 23, 2026
Delivery Method:
VIA Electronic Mail
Product:
Medical Devices
Recipient:
Recipient Name
Christopher Scoggins
Recipient Title
Executive Vice President of Diabetes Care
Abbott Diabetes Care, Inc.
1360 S Loop Rd
Alameda
,
CA
94502-7000
United States
(b)(4)
Issuing Office:
Center for Devices and Radiological Health
United States
WARNING LETTER
CMS # 722046
January 23, 2026
Dear Mr. Scoggins:
During an inspection of your firm located at 1360 S. Loop Rd, Alameda, CA 94502-7000, FEI #3002803444, on October 14, 2025, through October 23, 2025, an investigator from the United States Food and Drug Administration (FDA) determined that your firm manufactures FreeStyle Libre Flash and Continuous Glucose Monitoring Systems including the FreeStyle Libre 3. Under section 201(h) of the Federal Food, Drug, and Cosmetic Act (the Act), 21 U.S.C. § 321(h), these products are devices because they are intended for use in the diagnosis of disease or other conditions or in the cure, mitigation, treatment, or prevention of disease, or to affect the structure or function of the body.
Quality System Regulation Violations
This inspection revealed that these devices are adulterated within the meaning of section 501(h) of the Act, 21 U.S.C. § 351(h), in that 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 of the Quality System regulation found at Title 21,
Code of Federal Regulations
(CFR), Part 820.
We received your firm’s responses dated November 14, 2025, and December 19, 2025, from Christopher Scoggins and Denise Reid concerning our investigator’s observations noted on the Form FDA 483, List of Inspectional Observations (FDA 483) that was issued to your firm on October 23, 2025. These violations include but are not limited to the following:
1. Failure to adequately establish and maintain procedures to ensure that the device design is correctly translated into production specifications, as required by 21 CFR § 820.30(h).
For example, your firm has not established and maintained procedures for design transfer of your Project
(b)(4)
(FreeStyle Libre 3), specifically regarding transfer of performance specifications to third-party manufacturers. Your design transfer process did not ensure that performance specifications established in DOC40918 were translated into manufacturing specifications for your third-party manufacturer.
Your System Design Requirements,
(b)(4)
DOC40918 Rev. S, dated September 26, 2025, identifies sensor glucose accuracy performance requirements, including:
At least
(b)(4)
of sensor glucose results within ±
(b)(4)
or
(b)(4)
of reference
At least
(b)(4)
within ±
(b)(4)
of reference for adult population
At least
(b)(4)
within ±
(b)(4)
or ±
(b)(4)
of reference
At least
(b)(4)
within ±
(b)(4)
or ±
(b)(4)
of reference for adult population
At least
(b)(4)
within ±
(b)(4)
or ±
(b)(4)
of reference for adult population
Your firm established these requirements to comply with 21 CFR 862.1355 but did not transfer these specifications to your third-party manufacturer or ensure ongoing monitoring of in-process and finished product. Your firm failed to meet 21 CFR 862.1355(b)(3) special controls requirement that states: "design verification and validation must include adequate controls established during manufacturing and at product release to ensure the released product meets the performance specifications." No controls were established at final product release to ensure finished products meet performance specifications.
Additionally, DOC42469, Design Transfer Plan, Rev. D, does not describe how accuracy performance specifications derived from iCGM special controls are flowed down to external manufacturing sites or incorporated into their acceptance procedures. Contract manufacturers responsible for final assembly and release were not provided with accuracy performance requirements and were not required to verify finished-device accuracy performance prior to release.
We reviewed your firm's November 14, 2025, response and conclude it is not adequate. Your response does not identify whether finished-device accuracy performance release testing will be performed by Abbott or contract manufacturers, nor where these requirements are documented within the Device Master Record (DMR). Your Sensor Manufacturing Process Monitoring lacks: (1) specific performance specifications for glucose clinical accuracy; (2) direct linkage to the accuracy performance requirements at product release; and (3) adequate procedures to detect sensors that could produce erroneous glucose results. Your monitoring documents focus on general manufacturing parameters, biocontamination control, and facility requirements but inadequately address sensor glucose accuracy performance requirements. Your responsive attachments fail to demonstrate how the specific accuracy thresholds (
(b)(4)
) are translated into component-level specifications or systematically translated through all levels of manufacturing control.
We reviewed your firm's December 19, 2025, response and conclude it is not adequate. Although procedural updates were described, your firm did not provide objective evidence demonstrating that accuracy performance requirements have been fully transferred into production specifications, incorporated into the DMR, and implemented as acceptance procedures by manufacturing entities responsible for final assembly and release. Your response addresses Bluetooth (BLE) connectivity testing for FreeStyle Libre 2 rather than glucose accuracy performance for
(b)(4)
. The attachment implements interim sampling and testing but doesn't address design transfer procedure inadequacies. Your firm monitors BLE functionality by
(b)(4)
samples
(b)(4)
, but there is no evidence this correlates with glucose accuracy performance. The attachments contain extensive sampling protocols but do not demonstrate how glucose accuracy performance requirements (±
(b)(4)
, ±
(b)(4)
) are translated into component specifications in the Bill of Materials (BOM) or provide evidence of updates to design transfer procedures and revised component specifications. Additional testing (PCT and BLE) has been implemented but is not formally documented in design transfer documentation (DOC42469 and DOC42066), and there is no evidence of systematic review/revision of existing design transfer procedures (7.3W04). The new testing procedures lack sufficient detail on how they will detect sensors that could produce erroneous results due to causes in DOC40952-001.Although interim actions are implemented, permanent solutions such as
(b)(4)
won’t be operational until
(b)(4)
. This creates a
(b)(4)
gap where you appear to rely primarily on enhanced monitoring rather than systematic design transfer controls.
2. Failure to adequately establish and maintain procedures for finished device acceptance to ensure that each production run, lot, or batch of finished devices meets acceptance criteria, as required by 21 CFR 820.80(d).
For example, our inspection revealed that your firm releases finished FreeStyle Libre integrated continuous glucose monitoring system (iCGM) devices without performance-testing the finished, fully assembled, sterilized, programmed, and packaged devices for accuracy prior to distribution. The
(b)(4)
is performed only on unassembled sensor tails, prior to final assembly,
(b)(4)
sterilization, programming, packaging, and distribution. During the inspection, your firm’s management confirmed that finished devices are not performance-tested for accuracy at product release.
The iCGM special controls require that manufacturing and product release controls be established to ensure that released devices meet validated accuracy performance requirements (21 CFR 862.1355(b)(3)). Reliance on upstream, component-level testing performed prior to critical manufacturing steps does not ensure that finished, sterilized, and packaged devices meet accuracy performance requirements at the time of release. In addition, inspectional evidence documents that contract manufacturers responsible for final assembly and release were not provided accuracy performance specifications and were not required to verify finished-device accuracy performance prior to release. As a result, your firm has not established final acceptance activities to ensure that only conforming finished devices that meet the accuracy performance requirements are distributed, as required by 21 CFR 820.80(d).
Your firm’s responses dated November 14, 2025, and December 19, 2025, describe interim inspections, enhanced monitoring activities, and proposed future implementation of
(b)(4)
.
We reviewed your firm’s responses and conclude they are not adequate. The interim inspections and monitoring activities described are temporary, are not validated as manufacturing or release controls, and do not ensure that finished devices released to distribution meet validated accuracy performance requirements at the time of release. In addition, the proposed finished-device accuracy release testing has not been implemented and does not demonstrate that devices already release to distribution conform to validated accuracy performance requirements. Additionally, your response states you will continue to rely on the
(b)(4)
test for part of your acceptance activities, however, as noted below, we do not agree this test has been properly validated. Therefore, your firm has not established adequate manufacturing and product release controls to ensure compliance with 21 CFR 862.1355(b)(3) and 21 CFR 820.80(d).
3. Failure to adequately establish and maintain procedures, where appropriate, for identifying valid statistical techniques required for establishing, controlling, and verifying the acceptability of process capability and product characteristics, as required by 21 CFR 820.250(a).
For example, our inspection revealed that your firm failed to establish statistically valid acceptance criteria and sampling plans to ensure that only conforming finished devices are released to distribution. DOC42012, Rev. B, Section 9.1 (pp. 5-7) states that an observed in-vivo precision value of approximately
(b)(4)
CV was decomposed into equal between-subject and between-sensor components, resulting in an estimated between-sensor CV of
(b)(4)
, which was then used to derive
(b)(4)
precision acceptance limits.
The clinical performance monitoring study used to support this composition (
(b)(4)
) does not permit separation of manufacturing-related sensor variability from subject-related, physiological, behavioral, and reference-method variability because
(b)(4)
. As a result, the observed in-vivo variability reflects a conflation of uncontrolled sources, and no objective evidence was provided demonstrating that subject-related and sensor-related variance components can be reliably partitioned using this study design.
We reviewed your firm’s responses and conclude they are not adequate. Your response dated November 14, 2025, Table 1: Summary of Product Release Testing (pp. 4-5), proposes sampling plans for finished-device precision testing, deployment testing, BLE communication testing, and programming verification without providing statistical justification, such as confidence levels, power analyses, assumed defect rates, or risk-based rationale, as required by 21 CFR 820.250(a). Your response further proposes
(b)(4)
to
(b)(4)
without demonstrating that the sample size is adequate to detect failures associated with distinct failure modes.
Your firm has not established statistically valid acceptance criteria or sampling plans and has not provided objective evidence demonstrating that proposed sampling strategies are sufficient to ensure detection of nonconforming finished devices. Therefore, FDA lacks assurance that final acceptance activities are adequate to ensure that only conforming finished devices are released, as required by 21 CR 820.250(a) and 21 CFR 820.80(d).
4. Failure to adequately establish and maintain design validation procedures to ensure that devices conform to defined user needs and intended uses and shall include testing of production units under actual or simulated use conditions, as required by 21 CFR 820.30(g).
For example, although the FreeStyle Libre iCGM previously demonstrated compliance with accuracy performance requirements during premarket review, the inspection revealed that your firm failed to adequately validate that the
(b)(4)
, as implemented, is an appropriate manufacturing and release control to ensure preservation of that validated performance.
Specifically, DOC42012, Rev. B, Section 9.1 (pp. 5-7) states that
(b)(4)
specifications were derived from the post-market performance monitoring study
(b)(4)
, which uses
(b)(4)
measurements as the reference method. However, the iCGM special controls require that accuracy performance be ensured using an FDA-accepted laboratory reference method that is precise, accurate, and traceable to a higher-order reference (21 CFR 862.1355(b)(1)(ii)).
In addition, DOC42012, Rev. B, Table 2 (pp. 6-7) describes attempts to convert
(b)(4)
accuracy results to
(b)(4)
accuracy using
(b)(4)
derived from comparisons between studies with fundamentally different designs, subject populations, and reference methods. Further DOC42012, Rev. B, Sections 9.1.2-9.1.5 and Section 10 (pp. 12-18) assert equivalence between
(b)(4)
confidence intervals and the one-sided 95% lower confidence bounds required by regulation, despite evidence that the underlying error distributions violate the assumptions necessary for such substitution. The iCGM Sensor Lot Release Specification Summary Memo dated October 21, 2025, further documents use of a weighted composite ±
(b)(4)
/±
(b)(4)
accuracy requirement than independent evaluation of each required glucose range.
We reviewed your firm’s responses and conclude that they are not adequate. The interim monitoring activities and proposed future testing do not provide objective evidence validating
(b)(4)
, as currently implemented, as a manufacturing or release control capable of ensuring that finished devices continue to meet validated accuracy performance requirements. Therefore, your firm has not adequately validated its manufacturing and release controls, as required by 21 CFR 820.30(g) and 21 CFR 862.1355(b)(3).
Your firm should take prompt action to address any violations identified in this letter. Failure to adequately address this matter may result in regulatory action being initiated by the FDA without further notice. These actions include, but are not limited to, seizure, injunction, and civil money penalties. Other federal agencies may take your compliance with the FD&C Act and its implementing regulations into account when considering the award of federal contracts. Additionally, should FDA determine that you have Quality System regulation violations that are reasonably related to premarket approval applications for Class III devices, such devices will not be approved until the violations have been addressed. Should FDA determine that your devices or facilities do not meet the requirements of the Act, requests for Certificates to Foreign Governments (CFG) may not be granted.
Please notify this office in writing within fifteen business days from the date you receive this letter of the specific steps your firm has taken to address the noted violations, as well as an explanation of how your firm plans to prevent these violations, or similar violations, from occurring again. Include documentation of the corrections and/or corrective actions (which must address systemic problems) that your firm has taken. If your firm’s planned corrections and/or corrective actions will occur over time, please include a timetable for implementation of those activities. If corrections and/or corrective actions cannot be completed within fifteen business days, state the reason for the delay and the time within which these activities will be completed. Your firm’s response should be comprehensive and address any violations included in this Warning Letter. If you believe that your products are not in violation of the FD&C Act, include your reasoning and any supporting information for our consideration as part of your response.
Your firm’s response should be sent via email to Establishment Assessment Team 3 Acting Assistant Director, Jeffrey Wooley, at CDRHEnforcement@fda.hhs.gov. Please include in the subject line, “CMS Case 722046” when replying. If you have any questions about the contents of this letter, please contact: Compliance Officer, Raymond W. Brullo, via email at raymond.brullo@fda.hhs.gov
Finally, you should know that this letter is not intended to be an all-inclusive list of the violations at your firm’s facility. It is your firm’s responsibility to ensure compliance with applicable laws and regulations administered by FDA. The specific violations noted in this letter and in the Inspectional Observations, FDA 483, issued at the close of the inspection may be symptomatic of serious problems in your firm’s manufacturing and quality management systems. Your firm should investigate and determine the causes of the violations and take prompt actions to correct the violations and bring the products into compliance.
Sincerely,
/S/
Barbara C. Marsden
Acting Director
Office of Regulatory Programs
Office of Product Evaluation and Quality
Center for Devices and Radiological Health
cc: Ms. Denise Reid, Divisional Vice President Quality Assurance & Compliance
denise.reid@abbott.com
Content current as of:
02/03/2026
Regulated Product(s)
Medical Devices