A Comprehensive Performance Evaluation of Five Blood Glucose Systems in the Hypo-, Eu-, and Hyperglycemic Range

Analysis of "Capillary and Venous Blood Glucose Accuracy in Blood Glucose Meters Versus Reference Standards: The Impact of Study Design on Accuracy Evaluations"

The article by Macleod and coauthors outlines an accuracy study of two blood glucose monitoring systems (BGMSs) against glucose-oxidase- and hexokinase-based assays showing how the reference/comparison method and inappropriate sample comparisons can affect accuracy conclusions. The dangers of independent institutions producing inappropriate conclusions when the methodology used for product regulatory or registration accuracy requirements is not according to best practice are stressed. The authors highlight several important aspects of a multistep accuracy evaluation protocol. However, it is essential that anyone undertaking or reporting BGMS accuracy studies should have a clear understanding of each and every protocol point, best practice, and how each can influence accuracy conclusions. Claims against regulatory accuracy criteria should be made only if the detailed specified protocol design and analysis is followed.

A Review of Blood Glucose Monitor Accuracy

The aim of this study was to assess the accuracy of blood glucose monitors (BGMs) from studies reported in the medical literature. A literature review was performed of publications between 2010 and 2017 that presented data about the accuracy of BGMs using ISO 15197 2003 and/or ISO 15197 2013 as target standards. We found 58 publications describing the performance of 143 unique BGM systems, 59 of which were Food and Drug Administration (FDA) cleared. When compared with non-FDA-cleared BGMs, FDA-cleared BGMs were significantly more likely to pass both ISO 15197 2003 (OR = 2.39, CI 1.45-3.92, P < 0.01) and ISO 15197 2013 standards (OR = 2.20, CI 1.51-3.27, P < 0.01). Newer meters were more likely to pass both ISO 15197 2003 and ISO 15197 2013 standards. Many of the studies were supported by BGM manufacturers, and when compared with independent studies, an FDA-cleared BGM was significantly more likely to pass in a manufacturer-supported study for both ISO 15197 2003 (OR = 22.4, CI 8.73-21.57, P < 0.001) and ISO 15197 2013 (OR = 23.08, CI 10.16-60.03, P < 0.001). BGM accuracy should be assessed independently following regulatory clearance to ensure accurate performance. Failure to meet performance levels mandated by standards can result in deleterious clinical and economic effects.

Evaluation of Four Blood Glucose Monitoring Systems for Self-Testing with Built-in Insulin Dose Advisor Based on ISO 15197:2013: System Accuracy and Hematocrit Influence

BACKGROUND

Self-monitoring of blood glucose (SMBG) is important in diabetes therapy; however, not all SMBG systems are sufficiently accurate. In addition, some SMBG systems are influenced by the user's hematocrit value.

METHODS

System accuracy and hematocrit influence was evaluated for four SMBG systems with built-in insulin dose advisors (Accu-Chek^® Aviva Expert [1], FreeStyle InsuLinx [2], FreeStyle Precision Neo [3], MyStar DoseCoach^® [4]) based on International Organization for Standardization (ISO) 15197:2013 section 6.3 (system accuracy) and 6.4.3 (packed cell volume [hematocrit]) with three test strip lots for each system. Two different established comparison methods were used to investigate a possible impact of the comparison method on analytical performance data.

RESULTS

Two systems (2, 4) fulfilled ISO 15197:2013 accuracy criteria when the manufacturer's comparison measurement method was applied and showed with all three tested lots 97% to 99.5% of results within ±15 mg/dL and ±15% of the comparison measurement results at blood glucose (BG) concentrations <100 and ≥100 mg/dL, respectively, and 100% of results within consensus error grid zones A and B. Regarding hematocrit influences, two systems (3, 4) showed with all three tested lots ≤10 mg/dL and ≤10% difference between the test sample and the respective control sample for BG concentrations <100 and ≥100 mg/dL, respectively, when using the manufacturer's comparison measurement method.

CONCLUSIONS

When using the manufacturer's comparison measurement method, two out of four SMBG systems fulfilled the minimum system accuracy requirements of ISO 15197:2013. In addition, varying hematocrit levels can affect measurement results with some SMBG systems with built-in insulin dose advisors.

Retrospective Analysis of Continuous Glucose Monitoring Data With the Surveillance Error Grid Supports Nonadjunctive Dosing Decisions

OBJECTIVE

The objective was to assess clinical risks of inaccurate continuous glucose monitoring (CGM) system readings as estimated by the surveillance error grid (SEG).

METHODS

Values from Dexcom G4 Platinum system with an advanced algorithm (Software 505) were plotted on the SEG with temporally matched reference venous (YSI) values collected during clinic visits on days 1, 4, and 7 of sensor wear. Data from a pediatric study (N = 79, age [mean ± SD] 12.2 ± 4.6 years, all with type 1 diabetes) and an adult study (N = 51, age 46.7 ± 15.8 years, 44 with type 1 diabetes and 7 with type 2 diabetes) were used.

RESULTS

Pediatric data included 2262 paired points, of which 1990 (88.0%) were in the "no risk" zone. Adult data included 2263 paired points, of which 2056 (90.9%) were in the "no risk" zone. Performance was best on Day 4, when 92.7% and 93.3% of points from the pediatric and adult studies, respectively, were in the "no risk" zone. Nine of the 4525 points (<0.2%) from 5 different sensors were in zones representing moderate risk, and none were in zones representing great or extreme risk.

CONCLUSIONS

SEG analysis suggests that in pediatric and adult subjects with diabetes, using CGM values for diabetes management poses minimal risk to the user. CGM users also benefit from glucose trends and alerts.