Cook and Chill: Effect of Temperature on the Performance of Nonequilibrated Blood Glucose Meters

Evaluation of System Accuracy, Precision, Hematocrit Influence, and User Performance of Two Blood Glucose Monitoring Systems Based on ISO 15197:2013/EN ISO 15197:2015

INTRODUCTION

Sufficiently high analytical quality of blood glucose monitoring systems (BGMS) is a prerequisite for efficient diabetes therapy. In this study we assessed system accuracy, measurement repeatability, intermediate measurement precision, user performance, and the influence of hematocrit on two CE-marked blood glucose monitoring systems. For one BGMS, measurement accuracy using venous samples was additionally investigated.

METHODS

Study procedures were based on the International Organization of Standardization (ISO) 15197:2013/EN ISO 15197:2015 ("ISO 15197"). User performance included data from 100 subjects who used one test strip lot, whereas for all other analyses three different reagent system lots were used. For system accuracy assessment, 100 capillary samples were measured in duplicate with each of three reagent system lots per system, resulting in 600 results per system.

RESULTS

CareSens S Fit and CareSens H Beat both fulfilled the ISO 15197 accuracy criteria with 97.5-100% of each test strip lot's results falling within ± 15 mg/dL or ± 15% of the results of the comparison method and 100% of results in consensus error grid (CEG) zone A for all three lots. User performance evaluation revealed sufficient accuracy in the hands of lay users although some handling errors were documented by study staff. Assessment of measurement repeatability and intermediate measurement precision is given by standard deviation (SD) (glucose levels < 100 mg/dL) and by coefficient of variation (CV) (glucose concentrations ≥ 100 mg/dL). SD was ≤ 4.1 mg/dL and CV ≤ 4.2% for measurement repeatability and SD was ≤ 2.2 mg/dL and CV ≤ 2.6% for intermediate measurement precision. In case of hematocrit influence, both BGMS complied with all three tested lots with the defined criteria.

CONCLUSION

Both BGMS analyzed in this study fulfilled the required accuracy criteria of ISO 15197. They showed high precision, good performance in the hands of lay users, and the influence of hematocrit was acceptable in the labeled range.

Effects of Simulated Adverse Environmental Conditions Related to Actual Conditions at Health Promoting Hospitals on the Performance of Blood Glucose Testing by Glucose Meters

BACKGROUND

Annual peaks in temperature and humidity exceed manufacturers' specifications for blood glucose test strip storage in Thailand. Health Promoting Hospitals (HPH) do not always provide the same level of health services that hospitals do since they often only turn on air-conditioning units during working hours.

METHODS

The blood glucose testing performance of 4 glucose meters were investigated for short and long terms stress at 5 simulated conditions. Temperature and relative humidity (RH) at 5 HPHs in different regions of Thailand were monitored for 9 weeks during April to July 2019. The use of air conditioning in storage rooms for storing test strips was surveyed at 131 HPHs using questionnaires.

RESULTS

Median-paired differences of glucose measurements with stressed test strips in 5 simulated conditions significantly differed (P < 0.05) both in the short term (3 days) and in the long term (30 days) with 4 glucose meters when compared to unstressed test strips. The average temperature of all HPHs exceeded 30°C (86°F). The average RH was 84%. There was only one HPH that occasionally turned on its air conditioners. Most HPHs kept both opened and unopened vials of test strips in rooms without air conditioners. Further, 21.4-32.0% of HPHs kept test strips at room with air conditioners.

CONCLUSIONS

This study provides evidence for poor performance of blood glucose testing by glucose meters that are affected by adverse environmental conditions. The environmental for test strips storage at HPHs should be considered to prevent analytical errors of glucose measurement.

Assessment of System Accuracy, Intermediate Measurement Precision, and Measurement Repeatability of a Blood Glucose Monitoring System Based on ISO 15197

BACKGROUND

Analytical quality of blood glucose monitoring systems (BGMS) is an important aspect for many diabetes patients. Sufficiently high analytical quality is required for adequate diabetes therapy.

METHODS

In this study, system accuracy and measurement precision of a BGMS were assessed based on ISO 15197:2013. For system accuracy, this standard requires a specific glucose distribution and at least 95% of results obtained with the BGMS in capillary blood to fall within ±15 mg/dl or ±15% (at glucose concentrations <100 mg/dl or ≥100 mg/dl, respectively) of corresponding comparison method results, and at least 99% of results to be found within clinically acceptable consensus error grid (CEG) zones A and B. Based on ISO 15197:2013, intermediate measurement precision, using control solution, and measurement repeatability, using venous blood samples, were analyzed by calculation of standard deviations (SDs) and coefficients of variation (CV) at glucose concentrations <100 mg/dl or ≥100 mg/dl, respectively, although ISO 15197:2013 does not specify acceptance criteria.

RESULTS

The BGMS fulfilled system accuracy requirements with ≥99% of results within ±15 mg/dl or ±15% of the comparison method results, and 100% of results in CEG zones A and B. Intermediate measurement precision analysis showed SD ≤2.2 mg/dl and CV ≤2.3%. Analysis of measurement repeatability showed SD ≤2.1 mg/dl and CV ≤2.4%.

CONCLUSION

System accuracy requirements of ISO 15197:2013 were fulfilled by the BGMS. As ISO 15197:2013 does not specify precision requirements, precision analysis results were compared with those reported for other BGMS in the literature and found to be similar.

Accuracy of five systems for self-monitoring of blood glucose in the hands of adult lay-users and professionals applying ISO 15197:2013 accuracy criteria and potential insulin dosing errors

OBJECTIVE

In this study, accuracy in the hands of intended users was evaluated for five self-monitoring of blood glucose (SMBG) systems based on ISO 15197:2013, and possibly related insulin dosing errors were calculated. In addition, accuracy was assessed in the hands of study personnel.

METHODS

For each system (Accu-Chek ¹ Aviva Connect [A], Contour ² Next One [B], FreeStyle Freedom Lite ³ [C], GlucoMen ⁴ areo [D] and OneTouch Verio ⁵ [E]) one test strip lot was evaluated as required by ISO 15197:2013, clause 8. Number and percentage of SMBG measurements within ±15 mg/dl and ±15% of the comparison measurements at glucose concentrations <100 mg/dl and ≥100 mg/dl, respectively, were calculated. In addition, data is presented in surveillance error grids, and insulin dosing errors were modeled. The study was registered at ClinicalTrials.gov (NCT03033849).

RESULTS

Four systems (A, B, C, D) fulfilled the tested reagent system lot ISO 15197:2013 accuracy criteria with the tested reagent system lot with at least 95% (lay-users) and 99.5% (study personnel) of results within the defined limits. Measurements with all five systems were within the clinically acceptable zones of the consensus error grid and the surveillance error grid. Median modeled insulin dosing errors were between -0.8 and +0.6 units for measurements performed by lay-users and between -0.7 and +0.8 units for study personnel. Frequent lay-user errors were not checking the test strips' expiry date, applying blood incorrectly and handling the device incorrectly.

CONCLUSION

In this study, the systems showed slight differences in the number of results within ISO 15197:2013 accuracy limits. Inaccurate SMBG measurements can result in insulin dosing errors and adversely affect glycemic control.

Evaluation of Analytical Performance of Three Blood Glucose Monitoring Systems: System Accuracy, Measurement Repeatability, and Intermediate Measurement Precision

INTRODUCTION

Blood glucose monitoring systems (BGMS) should provide sufficient analytical quality to allow adequate therapy for diabetes patients. Besides system accuracy, measurement precision is an important aspect of a BGMS' analytical quality.

METHODS

Based on ISO 15197:2013/EN ISO 15197:2015, system accuracy, measurement repeatability, and intermediate measurement precision were assessed. ISO 15197:2013 system accuracy criteria require that ⩾95% of individual BGMS' test strip lot results shall fall within ±15 mg/dl or ±15% of corresponding comparison method results (at glucose concentrations <100 mg/dl and ⩾100 mg/dl, respectively), and that ⩾99% of results fall within consensus error grid (CEG) zones A and B. Measurement repeatability was assessed using venous blood samples, whereas intermediate measurement precision was assessed using control solution samples. Standard deviation (SD) and coefficient of variation (CV) were calculated for glucose concentrations <100 mg/dl and ⩾100 mg/dl, respectively. Precision acceptance criteria are not specified by ISO 15197:2013.

RESULTS

All three BGMS fulfilled system accuracy criteria with 96% to 98% of individual test strip lot's results falling within the acceptable accuracy limits. All measurement results fell within CEG zones A and B. For measurement repeatability, SD was ⩽3.3 mg/dl, and CV was ⩽3.9% for the investigated BGMS. Assessment of intermediate measurement precision showed SD ⩽1.3 mg/dl and CV ⩽3.0%.

CONCLUSION

All three BGMS fulfilled system accuracy criteria of ISO 15197:2013. In absence of acceptance criteria, precision results were found to be consistent with the manufacturer's labeling of the investigated devices.

Interferences and Limitations in Blood Glucose Self-Testing: An Overview of the Current Knowledge

In general, patients with diabetes performing self-monitoring of blood glucose (SMBG) can strongly rely on the accuracy of measurement results. However, various factors such as application errors, extreme environmental conditions, extreme hematocrit values, or medication interferences may potentially falsify blood glucose readings. Incorrect blood glucose readings may lead to treatment errors, for example, incorrect insulin dosing. Therefore, the diabetes team as well as the patients should be well informed about limitations in blood glucose testing. The aim of this publication is to review the current knowledge on limitations and interferences in blood glucose testing with the perspective of their clinical relevance.