Clinical Accuracy of a Glucose Oxidase-Based Blood Glucose Test-Strip Across Extremes of Oxygen Partial Pressure.

Background: Glucose oxidase (GOx)-based blood glucose monitors (BGMs) are influenced by the partial pressure of oxygen (Po₂) within the applied sample. Limited in-clinic data exists regarding the quantitative effect of Po₂ in unmanipulated capillary fingertip blood samples across physiologically representative glucose and Po₂ ranges.

Method: Clinical accuracy data were collected as part of a BGM manufacturer's ongoing post-market surveillance program for a commercially available GOx-based BGM test-strip. The data set comprised 29 901 paired BGM-comparator readings and corresponding Po₂ values from 5 428 blood samples from a panel of 975 subjects.

Results: A linear regression-calculated bias range of 5.22% (+0.72% [low Po₂: 45 mm Hg] to -4.5% [high Po₂: 105 mm Hg]); biases calculated as absolute at <100 mg/dL glucose was found. Below the nominal Po₂ of 75 mm Hg, a linear regression bias of +3.14% was calculated at low Po₂, while negligible impact on bias (regression slope: +0.002%) was observed at higher than nominal levels (>75 mm Hg). When evaluating BGM performance under corner conditions of low (<70 mg/dL) and high (>180 mg/dL) glucose, combined with low and high Po₂, linear regression biases ranged from +1.52% to -5.32% within this small group of subjects and with no readings recorded at <70 mg/dL glucose at low and high Po₂.

Conclusions: Data from this large-scale clinical study, performed on unmanipulated fingertip capillary bloods from a diverse diabetes population, indicate Po₂ sensitivity of the BGM to be markedly lower than published studies, which are mainly laboratory-based, requiring artificial manipulation of oxygen levels in aliquots of venous blood.