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The microdot 9 Home Blood Glucose Monitoring System is intended for self testing outside the body (in vitro diagnostic use only), by people with diabetes at home as an aid to monitor the effectiveness of diabetes control. It is intended for "single patient-home use" only and should not be shared. It should be used only for testing fresh capillary whole blood samples from a fingerstick or palm for glucose (sugar). Alternate site testing should be done only during steady-state times (when glucose is not changing rapidly). It is not intended for use on neonates or in the diagnosis of or screening for diabetes mellitus.

The system consists of the microdot® Home Blood Glucose meter, microdot® Home Test Strips and microdot® Control solutions.

microdot® Home Test Strips

The microdot® Home Test strips are intended for the quantitative measurement of glucose in fresh capillary whole blood from a fingerstick or palm.

The microdot® Home Blood Glucose Monitoring System consists of the microdot® Home Blood Glucose Meter, microdote Home Test Strips, microdot Control Solutions and a commercially available (510(k) cleared) lancing device and lancets. A clear cap is provided with the lancing device for alternate site testing on the palm. microdote Home Blood Glucose Monitoring System is for a single patient use only. The meter and lancing device must not be shared with anyone.

microdot® Home is an auto code system. The meter turns on upon insertion of the strip, a blood sample from the finger or palm is applied to the test strip and after 10 seconds, the plasma glucose result is displayed on the screen in mg/dL only.

microdot Home Blood Glucose Monitoring System is substantially equivalent in form, firmware, fundamental scientific technology and specifications as the predicate system, microdot® Xtra Blood Glucose Monitoring System. It relies on quantitative electrochemical biosensor technology to measure current generated on disposable test strips.

The strip remains unchanged since the last submission approval, microdot® Xtra Blood Glucose Monitoring System (K083273). The Test Strip manufacturing and performance characteristics are unchanged. The test strips are designed to quantitatively measure glucose in fresh capillary blood from the fingertip by persons with diabetes.

The microdot® Home Blood Glucose Monitoring System device received 510(k) clearance (K102383) in 2012. The submission focused on adding palm testing as an alternate site for an existing product.

Here's an analysis of the acceptance criteria and the study that supports it:

1. Acceptance Criteria and Reported Device Performance

The acceptance criteria for glucose monitoring systems for self-testing are generally defined by ISO 15197. The document explicitly references ISO15197:2003: in vitro diagnostic test systems - requirements for blood-glucose monitoring systems for self testing in managing diabetes mellitus (Section 8: User Performance). While the exact acceptance criteria thresholds from ISO15197:2003 are not explicitly listed in the 510(k) summary, the performance data is presented in a way that suggests alignment with such standards, using percentage agreement within specific glucose ranges and mg/dL deviations.

The performance is reported against a reference method, likely YSI (Yellow Springs Instrument), which is a common laboratory reference for glucose measurement.

Note: The thresholds implicitly referenced by ISO 15197:2003 usually require a high percentage of results to fall within certain accuracy windows, e.g., 95% within ±15 mg/dL or ±15% (whichever is greater). Based on the provided data, the device appears to meet or exceed commonly accepted accuracy standards for point-of-care blood glucose meters, especially for the palm testing demonstrating comparable performance to fingerstick.

2. Sample Size and Data Provenance

• Sample Size for the Test Set: 152 diabetic individuals.
• Data Provenance: The study was a "consumer study" where diabetics tested themselves. The country of origin is not explicitly stated, but the applicant (Cambridge Sensors Limited) is based in the United Kingdom. It is a prospective study as it involves individuals taking samples and performing tests according to instructions.

3. Number of Experts and Qualifications for Ground Truth

• Number of Experts: The document mentions "healthcare professionals testing at finger only" alongside the diabetic subjects. It does not specify the exact number of healthcare professionals.
• Qualifications of Experts: The qualifications of the healthcare professionals are not explicitly detailed, but it's implied they are trained to accurately perform fingerstick blood glucose measurements.

4. Adjudication Method

The document does not explicitly describe an adjudication method for establishing ground truth, such as 2+1 or 3+1 consensus. The comparison is made directly against a reference instrument (YSI), implying the YSI result is considered the gold standard, and there's no mention of expert consensus on the device's readings. For "user performance" studies in blood glucose, the reference method (e.g., YSI) itself often serves as the adjudicated truth, with subject readings being compared to it directly rather than being reviewed by additional experts.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

There is no MRMC comparative effectiveness study described. This study directly compares the device's readings (from both subjects and HCPs) against a reference method (YSI) for individual measurements. It does not assess the improvement of human readers (clinicians or patients) with or without AI assistance, as it's a direct instrumental comparison for a diagnostic device.

6. Standalone (Algorithm Only) Performance

Yes, a standalone performance study was done. The accuracy tables (Summary of Accuracy Results for all sites tested) directly report the performance of the device's measurements (from palm and fingerstick) compared to the YSI reference. This is an evaluation of the algorithm and sensor's ability to accurately measure glucose without human interpretation impacting the result, beyond the user properly applying the sample.

7. Type of Ground Truth Used

The type of ground truth used is a reference laboratory method, specifically "YSI". YSI (Yellow Springs Instrument) glucose analyzers are widely considered a gold standard for blood glucose measurement in clinical studies due to their high precision and accuracy.

8. Sample Size for the Training Set

The document explicitly states that performance characteristics like "Precision/Reproducibility", "Linearity/assay reportable range", "Traceability, Stability'", "Detection Limit", and "Analytical Specificity" were "Established in original submission (K070524)". This indicates that the core analytical performance of the test strip was already validated.

The current submission adds palm testing as an alternate site. Therefore, the "training set" for the algorithm itself is not discussed, as the underlying electrochemical biosensor technology and the strip design are stated to be unchanged from previous submissions. The study described (with 152 diabetics) serves as the clinical validation set for the expanded use (palm testing), not a training set for the algorithm.

9. How the Ground Truth for the Training Set was Established

As mentioned above, the details of the ground truth establishment for the original analytical performance (K070524) are not provided in this 510(k) summary. However, for glucose meters, the ground truth for training and validating the core algorithm (which translates the electrochemical signal to a glucose reading) typically involves comparing device readings from a large number of blood samples (spiked or native) across a wide range of glucose concentrations to a highly accurate reference laboratory method, such as a YSI glucose analyzer or hexokinase method.

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