Influence of Partial Pressure of Oxygen in Blood Samples on Measurement Performance in Glucose-Oxidase-Based Systems for Self-Monitoring of Blood Glucose

Background

Partial pressure of oxygen (pO₂) in blood samples can affect blood glucose (BG) measurements, particularly in systems that employ the glucose oxidase (GOx) enzyme reaction on test strips. In this study, we assessed the impact of different pO₂ values on the performance of five GOx systems and one glucose dehydrogenase (GDH) system. Two of the GOx systems are labeled by the manufacturers to be sensitive to increased blood oxygen content, while the other three GOx systems are not.

Methods

Aliquots of 20 venous samples were adjusted to the following pO₂ values: <45, ~70, and ≥150 mmHg. For each system, five consecutive measurements on each sample aliquot were performed using the same test strip lot. Relative differences between the mean BG results at pO₂ ~70 mmHg, which is considered to be similar to pO₂ in capillary blood samples, and the mean BG result at pO₂ <45 and ≥150 mmHg were calculated.

Results

For all tested GOx systems, mean relative differences in the BG measurement results were between 6.1% and 22.6% at pO₂ <45 mmHg and between -7.9% and -14.9% at pO₂ ≥150 mmHg. For both pO₂ levels, relative differences of all tested GOx systems were significant (p < .0001). The GDH system showed mean relative differences of -1.0% and -0.4% at pO₂ values <45 and ≥150 mmHg, respectively, which were not significant.

Conclusions

These data suggest that capillary blood pO₂ variations lead to clinically relevant BG measurement deviations in GOx systems, even in GOx systems that are not labeled as being oxygen sensitive.