Accuracy and reliability of the Nova StatStrip® glucose meter for real-time blood glucose determinations during glucose clamp studies

Abstract

Aims/hypothesis: The Andres clamp technique, which requires accurate and timely determination of glucose, utilizes the Beckman or Yellow Springs Instruments (YSI) glucose analyzers. Both instruments require maintenance, a dedicated operator, preparation of a plasma sample, and a duplicate measurement that takes ≥2 minutes. The Nova StatStrip glucose meter was evaluated for accuracy, reliability, and near-real-time availability of glucose.

Methods: Blood samples from 24 patients who underwent 6-hour clamp studies and 12 patients who had a standardized meal tolerance test (SMT) were measured. Specimens were analyzed simultaneously and immediately upon collection by Beckman, YSI, and Nova.

Results: Of 1004 data pairs for the Nova device versus Beckman, the Nova data points ranged from 32 to 444, while Beckman ranged from 42 to 412. The coefficient for the slope of Beckman versus Nova was 1.009 (r = 0.978). Using error grid analysis, the number and percentage of values for Nova were 976 (97.2%) in the A zone and 28 (2.8%) in the B zone. Of 399 data pairs for the Nova device versus YSI, the Nova data points ranged from 46 to 255, whereas YSI ranged from 47 to 231. The coefficient for the slope of YSI versus Nova was 1.023 (r = 0.989). All Nova readings fell in the A zone. Time required for final reading, in duplicate, was 15 seconds for Nova and 120-180 seconds for Beckman and YSI.

Conclusions: The simplicity of Nova and its reliability, accuracy, and speed make it an acceptable replacement device for Beckman and YSI in the conduct of clamps, especially when perturbations require rapid glucose determination.

© 2010 Diabetes Technology Society.

Figures

Figure 1.

Comparison of PG values between Beckman and Nova devices during a hyperinsulinemic–euglycemic clamp (0–180 min), during a hyperglycemic clamp (180–200 min), and during recovery from hyperglycemia (300–330 min).

Figure 2.

Scatter plot with EGA for pairs of Beckman and Nova (top) and YSI and Nova (bottom) blood glucose values using Beckman and YSI as the respective reference method.

Figure 3.

Bland–Altman plot comparing the difference between Nova and Beckman (top) and Nova and YSI (bottom) readings of the same blood sample. Solid line represents mean difference, and dashed lines show two standard deviations above and below the mean (n = 1004 for Nova–Beckman comparison; n = 399 for Nova–YSI comparison).

Figure 4.

Bland–Altman plot comparing Beckman duplicate differences with Nova duplicate differences. Solid line represents mean difference, and dashed lines represent two standard deviations above and below each device's respective mean difference.

Figure 5.

Locally smoothed median absolute difference curve. The dashed horizontal line represents the recommended error tolerance (5 mg/dl).