Performance Evaluation of Three Blood Glucose Monitoring Systems Using ISO 15197: 2013 Accuracy Criteria, Consensus and Surveillance Error Grid Analyses, and Insulin Dosing Error Modeling in a Hospital Setting

Abstract

Background: Blood glucose monitoring is an essential component of diabetes management. Inaccurate blood glucose measurements can severely impact patients' health. This study evaluated the performance of 3 blood glucose monitoring systems (BGMS), Contour® Next USB, FreeStyle InsuLinx®, and OneTouch® Verio™ IQ, under routine hospital conditions.

Methods: Venous blood samples (N = 236) obtained for routine laboratory procedures were collected at a Spanish hospital, and blood glucose (BG) concentrations were measured with each BGMS and with the available reference (hexokinase) method. Accuracy of the 3 BGMS was compared according to ISO 15197:2013 accuracy limit criteria, by mean absolute relative difference (MARD), consensus error grid (CEG) and surveillance error grid (SEG) analyses, and an insulin dosing error model.

Results: All BGMS met the accuracy limit criteria defined by ISO 15197:2013. While all measurements of the 3 BGMS were within low-risk zones in both error grid analyses, the Contour Next USB showed significantly smaller MARDs between reference values compared to the other 2 BGMS. Insulin dosing errors were lowest for the Contour Next USB than compared to the other systems.

Conclusions: All BGMS fulfilled ISO 15197:2013 accuracy limit criteria and CEG criterion. However, taking together all analyses, differences in performance of potential clinical relevance may be observed. Results showed that Contour Next USB had lowest MARD values across the tested glucose range, as compared with the 2 other BGMS. CEG and SEG analyses as well as calculation of the hypothetical bolus insulin dosing error suggest a high accuracy of the Contour Next USB.

Keywords: Contour Next; accuracy; blood glucose monitoring system; consensus error grid; diabetes; glucose meter; insulin dosing error; surveillance error grid.

Figure 1.

Modified Bland–Altman plots for each BGMS, CNU (A), FIL (B), and OT (C). In each plot, the y-axis depicts the difference between meter result and the reference method result (mg/dL), and the x-axis is the BG value according to the reference method (mg/dL). The lower and upper limits (LL, UL, green and blue lines, respectively) are included in the plots and are either ±15 mg/dL (hexokinase < 100 mg/dL) or ±15% of Dimension EXL hexokinase (hexokinase ≥ 100 mg/dL). These limits are calculated in accordance to ISO 15197:2013 and are expressed in mg/dL.

Figure 2.

MARD among the 3 meter systems. Lower MARD values indicate smaller difference between reference value and meter value. Delta (Δ) indicates the MARD differences between the BGMS, and asterisks indicate statistical significance (**P < .01, ***P < .001) of the differences, calculated according to Tukey’s honestly significant difference (HSD).

Figure 3.

Consensus error grid analysis for the results obtained with the CNU (A), FIL (B), and OT (C). For each plot, the y-axis depicts the BGMS result, while the x-axis represents the result obtained with the reference method. The zones within each plot (A to E) indicate the increasing clinical significance of an erroneous measurement.

Figure 4.

Surveillance error grid analysis for each BGMS (CNU, FIL and OT). The y-axis depicts the BGMS readings, the x-axis the reference method BG measurement. The color-coded risk zone definition is according to Klonoff et al.

Figure 5.

Insulin dose error analysis. The x-axis is the insulin dose error (in insulin units). Bars show the 95% range of potential dose errors caused by erroneous measurements.