(280 days)
The Bigfoot Unity Diabetes Management System is indicated for the management of diabetes in persons age 12 years and older.
Bigfoot Unity provides glucose monitoring data via the Abbott FreeStyle Libre 2 Flash Glucose Monitoring sensor. The system incorporates real time alarm capabilities and is designed to replace blood glucose testing for diabetes treatment decisions, unless otherwise indicated. The device is intended to provide insulin dose information using the available glucose data to assist persons with diabetes mellitus who use disposable pen-injectors for the self-injection of insulin in implementing health care provider recommended insulin dose regimens. The device is intended for single patient use only and requires a prescription.
Bigfoot Unity is also intended to communicate autonomously with digitally connected medical devices where the user manually controls therapy decisions.
The Bigfoot Unity Diabetes Management System ('Bigfoot Unity System') integrates continuous glucose monitoring with insulin dose recommendations to support people with diabetes mellitus who use disposable insulin pens for self-injection of insulin. The system consists of the Abbott Diabetes Care, Inc.'s FreeStyle Libre 2 Flash Glucose Monitoring System ("FreeStyle Libre 2") integrated continuous glucose monitor (iCGM) sensor, two reusable insulin pen caps (one each for rapid-acting and long-acting insulin pens) and a mobile application. The components communicate via near field communication (NFC) and Bluetooth.
The device generates glucose data using the FreeStyle Libre 2 sensor and displays the data (value and trend) on the rapid-acting insulin pen cap. The rapid-acting pen cap also displays correction and meal insulin doses based upon settings prescribed by the user's healthcare provider and the available glucose data. The long-acting pen cap displays the long-acting insulin dose prescribed by the user's healthcare provider. From the dose recommendations on the pen caps as well as other contextually relevant information such as glucose trend arrows and current exercise status, users determine the doses to take. Users manually select an insulin dose and administer it using the pens according to the insulin manufacturers' instructions. In addition to dose information, both pen caps track the time of insulin doses.
The mobile app provides fixed and configurable system alerts based upon data generated by the FreeStyle Libre 2 sensor. It also enables entry of the healthcare provider prescribed insulin dosing regimen as well as provides system alerts and historical information. In addition, the mobile app manages the secure wireless communication between the system components and enables the transfer of the system data to the cloud.
The Bigfoot Unity Diabetes Management System is an integrated continuous glucose monitor (iCGM) designed to assist individuals with diabetes in managing their insulin doses. It incorporates the Abbott FreeStyle Libre 2 Flash Glucose Monitoring system and provides insulin dose recommendations based on glucose data.
Here's an analysis of the acceptance criteria and supporting studies as described in the provided document:
1. Table of Acceptance Criteria and Reported Device Performance
The document does not explicitly present a table of acceptance criteria with specific numerical targets and corresponding device performance metrics for the Bigfoot Unity System as a complete system beyond the predicate device's performance. Instead, it states that various tests met their respective acceptance criteria, implying successful performance without detailing those criteria quantitatively for this device.
However, it does reference the analytical and clinical performance of the Abbott FreeStyle Libre 2 Flash Glucose Monitor (K193371), which forms a core component of the Bigfoot Unity System. The acceptance criteria for the integrated system are, in part, based on the successful integration and continued performance of this pre-cleared component and the proper functionality of the new elements (pen caps, mobile app, dose recommendations).
Summary of General Performance Claims:
| Acceptance Criteria Category | Reported Device Performance |
|---|---|
| Bench Testing | "Bigfoot Unity System functioned as intended and the results of the testing met the acceptance criteria." |
| Human Factors & Usability | "User interface design and labeling would not impact the performance of the device." |
| Software Verification & Validation | "Software performed in accordance with established specifications... results of the software executed protocols for the Unity System met the acceptance criteria." |
| Biocompatibility | "Determined to be biocompatible per the requirements of ISO 10993-1: 2018." |
| Electromagnetic Compatibility & Electrical Safety | "Comply with the electrical safety and electromagnetic compatibility requirements in IEC 60601-1:2013, IEC/EN 60601-1-2:2014, IEC CISPR 11, and IEC 60601-1-11:2015." |
| Wireless Coexistence | "Demonstrated successful coexistence testing in the presence of common RF interfering devices." |
| Airworthiness | "Successfully demonstrated compliance with airworthiness requirements per the Federal Aviation Administration (FAA) Advisory Circular RTCA/DO-160." |
| Environmental Testing | "Ensured the device specifications for operating temperature, humidity, pressure, impact, vibration, shock, drop, and storage conditions were met." |
| Interoperability | "In alignment with FDA guidance, Design Considerations and Pre-market Submission Recommendations for Interoperable Medical Devices." |
| Cybersecurity | "Appropriate risk mitigation controls have been implemented and tested." |
2. Sample Size Used for the Test Set and Data Provenance
The document does not specify the sample size used for the test set for the Bigfoot Unity System's custom components (e.g., pen caps, mobile app, dose recommendations). It mentions "bench test results," "human factors and usability testing," "software verification and validation testing," and "wireless coexistence and EMC testing," but without numerical details on participants or data points.
For the Abbott FreeStyle Libre 2 Flash Glucose Monitor, its analytical and clinical performance was assessed under K193371. The provenance of this data would be from the studies submitted for that specific 510(k) clearance, which is not detailed in this document. Generally, such studies involve prospective clinical trials to evaluate accuracy against a reference method (e.g., YSI glucose analyzer) in a clinical or home-use setting, typically involving participants from various countries (though often with a significant US cohort).
The data concerning the Bigfoot Unity System's specific new features (dose recommendations, pen caps, mobile app) appears to be from retrospective testing (bench, software V&V, environmental) or prospective limited user testing (human factors) but no details of the number of participants or data origin are provided.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications
This information is not provided for the Bigfoot Unity System's specific components. For the Abbott FreeStyle Libre 2 (the iCGM component), the ground truth for its analytical accuracy would have been established using laboratory reference methods (e.g., YSI glucose analyzers) rather than human experts, with the data then statistically compared.
For the human factors testing, "experts" in usability engineering often oversee such studies, but the document does not specify their number or qualifications. The "ground truth" in human factors is often defined by the successful completion of critical tasks without errors, which is assessed against predefined task flows and safety parameters.
4. Adjudication Method for the Test Set
The document does not specify an adjudication method for any test sets related to the Bigfoot Unity System beyond the inherent statistical comparisons and validation processes for technical performance. Since no expert concensus or clinical outcome adjudication is explicitly mentioned for the new components, it appears that direct performance against established technical specifications or usability metrics was used.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
The document does not mention a multi-reader multi-case (MRMC) comparative effectiveness study. This type of study is more common for diagnostic imaging devices where human readers (e.g., radiologists) interpret images with and without AI assistance. The Bigfoot Unity System is an iCGM with dose recommendations, not an imaging device, so an MRMC study would generally not be applicable in this context. There is no information provided regarding the effect size of human readers improving with AI vs. without AI assistance.
6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study
The document does not explicitly describe a standalone algorithm-only performance study for the Bigfoot Unity System's dose recommendation functionality. However, the software verification and validation activities would have tested the internal logic and calculations of the algorithm in a standalone manner (i.e., verifying that given specific glucose data and patient settings, the algorithm outputs the correct dose recommendation according to its specifications). The output of the dose recommendation, while displayed to the user for manual action, is a direct algorithmic output. The performance of the FreeStyle Libre 2 sensor itself is a standalone performance of the glucose monitoring component.
7. Type of Ground Truth Used
For the glucose monitoring component (FreeStyle Libre 2), the ground truth is typically laboratory reference methods (e.g., YSI glucose analyzers for blood glucose levels).
For the Bigfoot Unity System's new components:
- Software Verification and Validation: Ground truth is established by pre-defined functional specifications and requirements. The software is verified to produce expected outputs given specific inputs.
- Human Factors: Ground truth is established by safety and usability metrics, where critical tasks are expected to be completed without error, and the interface is easily understandable.
- Bench, Environmental, EMC, Biocompatibility: Ground truth is established by international standards and regulatory requirements (e.g., ISO, IEC).
8. Sample Size for the Training Set
The document does not provide information on the sample size for the training set. The Bigfoot Unity System's dose recommendation functionality is based on a pre-programmed algorithm reflecting healthcare provider prescribed insulin dosing regimens, not a machine learning model that requires a "training set" in the conventional sense of supervised learning. The FreeStyle Libre 2 sensor would have undergone calibration and potentially model training (if AI is used for signal processing/accuracy improvements) but that detail is not provided here.
9. How the Ground Truth for the Training Set Was Established
As noted above, a "training set" for a machine learning model is not explicitly indicated for the Bigfoot Unity System's new components. The system primarily implements established clinical protocols for insulin dosing. Therefore, the "ground truth" for the dose recommendation logic would be based on clinical guidelines and established medical practice for insulin dosing, as prescribed by a healthcare provider. The software validates that it correctly implements these rules.
For the underlying FreeStyle Libre 2 iCGM, if it uses machine learning, the ground truth for any potential sensor calibration/algorithm training would have been established through comparison to laboratory reference glucose measurements (e.g., from YSI devices) from clinical studies.
§ 862.1355 Integrated continuous glucose monitoring system.
(a)
Identification. An integrated continuous glucose monitoring system (iCGM) is intended to automatically measure glucose in bodily fluids continuously or frequently for a specified period of time. iCGM systems are designed to reliably and securely transmit glucose measurement data to digitally connected devices, including automated insulin dosing systems, and are intended to be used alone or in conjunction with these digitally connected medical devices for the purpose of managing a disease or condition related to glycemic control.(b)
Classification. Class II (special controls). The special controls for this device are:(1) Design verification and validation must include the following:
(i) Robust clinical data demonstrating the accuracy of the device in the intended use population.
(ii) The clinical data must include a comparison between iCGM values and blood glucose values in specimens collected in parallel that are measured on an FDA-accepted laboratory-based glucose measurement method that is precise and accurate, and that is traceable to a higher order (
e.g., an internationally recognized reference material and/or method).(iii) The clinical data must be obtained from a clinical study designed to fully represent the performance of the device throughout the intended use population and throughout the measuring range of the device.
(iv) Clinical study results must demonstrate consistent analytical and clinical performance throughout the sensor wear period.
(v) Clinical study results in the adult population must meet the following performance requirements:
(A) For all iCGM measurements less than 70 milligrams/deciliter (mg/dL), the percentage of iCGM measurements within ±15 mg/dL of the corresponding blood glucose value must be calculated, and the lower one-sided 95 percent confidence bound must exceed 85 percent.
(B) For all iCGM measurements from 70 mg/dL to 180 mg/dL, the percentage of iCGM measurements within ±15 percent of the corresponding blood glucose value must be calculated, and the lower one-sided 95 percent confidence bound must exceed 70 percent.
(C) For all iCGM measurements greater than 180 mg/dL, the percentage of iCGM measurements within ±15 percent of the corresponding blood glucose value must be calculated, and the lower one-sided 95 percent confidence bound must exceed 80 percent.
(D) For all iCGM measurements less than 70 mg/dL, the percentage of iCGM measurements within ±40 mg/dL of the corresponding blood glucose value must be calculated, and the lower one-sided 95 percent confidence bound must exceed 98 percent.
(E) For all iCGM measurements from 70 mg/dL to 180 mg/dL, the percentage of iCGM measurements within ±40 percent of the corresponding blood glucose value must be calculated, and the lower one-sided 95 percent confidence bound must exceed 99 percent.
(F) For all iCGM measurements greater than180 mg/dL, the percentage of iCGM measurements within ±40 percent of the corresponding blood glucose value must be calculated, and the lower one-sided 95 percent confidence bound must exceed 99 percent.
(G) Throughout the device measuring range, the percentage of iCGM measurements within ±20 percent of the corresponding blood glucose value must be calculated, and the lower one-sided 95 percent confidence bound must exceed 87 percent.
(H) When iCGM values are less than 70 mg/dL, no corresponding blood glucose value shall read above 180 mg/dL.
(I) When iCGM values are greater than 180 mg/dL, no corresponding blood glucose value shall read less than 70 mg/dL.
(J) There shall be no more than 1 percent of iCGM measurements that indicate a positive glucose rate of change greater than 1 mg/dL per minute (/min) when the corresponding true negative glucose rate of change is less than −2 mg/dL/min as determined by the corresponding blood glucose measurements.
(K) There shall be no more than 1 percent of iCGM measurements that indicate a negative glucose rate of change less than −1 mg/dL/min when the corresponding true positive glucose rate of change is greater than 2 mg/dL/min as determined by the corresponding blood glucose measurements.
(vi) Data demonstrating similar accuracy and rate of change performance of the iCGM in the pediatric population as compared to that in the adult population, or alternatively a clinical and/or technical justification for why pediatric data are not needed, must be provided and determined by FDA to be acceptable and appropriate.
(vii) Data must demonstrate that throughout the claimed sensor life, the device does not allow clinically significant gaps in sensor data availability that would prevent any digitally connected devices from achieving their intended use.
(2) Design verification and validation must include a detailed strategy to ensure secure and reliable means of iCGM data transmission to provide real-time glucose readings at clinically meaningful time intervals to devices intended to receive the iCGM glucose data.
(3) Design verification and validation must include adequate controls established during manufacturing and at product release to ensure the released product meets the performance specifications as defined in paragraphs (b)(1) and (b)(2) of this section.
(4) The device must demonstrate clinically acceptable performance in the presence of clinically relevant levels of potential interfering substances that are reasonably present in the intended use population, including but not limited to endogenous substances and metabolites, foods, dietary supplements, and medications.
(5) The device must include appropriate measures to ensure that disposable sensors cannot be used beyond its claimed sensor wear period.
(6) Design verification and validation must include results obtained through a usability study that demonstrates that the intended user can use the device safely and obtain the expected glucose measurement accuracy.
(7) The labeling required under § 809.10(b) of this chapter must include a separate description of the following sensor performance data observed in the clinical study performed in conformance with paragraph (b)(1) of this section for each intended use population, in addition to separate sensor performance data for each different iCGM insertion or use sites (
e.g., abdomen, arm, buttock):(i) A description of the accuracy in the following blood glucose concentration ranges: less than 54 mg/dL, 54 mg/dL to less than 70 mg/dL, 70 to 180 mg/dL, greater than 180 to 250 mg/dL, and greater than 250 mg/dL.
(ii) A description of the accuracy of positive and negative rate of change data.
(iii) A description of the frequency and duration of gaps in sensor data.
(iv) A description of the true, false, missed, and correct alert rates and a description of the available glucose concentration alert settings, if applicable.
(v) A description of the observed duration of iCGM life for the device.