Clinical assessment of the accuracy of blood glucose measurement devices

Global variation in diabetes diagnosis and prevalence based on fasting glucose and hemoglobin A1c

Fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c) are both used to diagnose diabetes, but these measurements can identify different people as having diabetes. We used data from 117 population-based studies and quantified, in different world regions, the prevalence of diagnosed diabetes, and whether those who were previously undiagnosed and detected as having diabetes in survey screening, had elevated FPG, HbA1c or both. We developed prediction equations for estimating the probability that a person without previously diagnosed diabetes, and at a specific level of FPG, had elevated HbA1c, and vice versa. The age-standardized proportion of diabetes that was previously undiagnosed and detected in survey screening ranged from 30% in the high-income western region to 66% in south Asia. Among those with screen-detected diabetes with either test, the age-standardized proportion who had elevated levels of both FPG and HbA1c was 29-39% across regions; the remainder had discordant elevation of FPG or HbA1c. In most low- and middle-income regions, isolated elevated HbA1c was more common than isolated elevated FPG. In these regions, the use of FPG alone may delay diabetes diagnosis and underestimate diabetes prevalence. Our prediction equations help allocate finite resources for measuring HbA1c to reduce the global shortfall in diabetes diagnosis and surveillance.

The convergence of traditional and digital biomarkers through AI-assisted biosensing: A new era in translational diagnostics?

Advances in consumer electronics, alongside the fields of microfluidics and nanotechnology have brought to the fore low-cost wearable/portable smart devices. Although numerous smart devices that track digital biomarkers have been successfully translated from bench-to-bedside, only a few follow the same fate when it comes to track traditional biomarkers. Current practices still involve laboratory-based tests, followed by blood collection, conducted in a clinical setting as they require trained personnel and specialized equipment. In fact, real-time, passive/active and robust sensing of physiological and behavioural data from patients that can feed artificial intelligence (AI)-based models can significantly improve decision-making, diagnosis and treatment at the point-of-procedure, by circumventing conventional methods of sampling, and in person investigation by expert pathologists, who are scarce in developing countries. This review brings together conventional and digital biomarker sensing through portable and autonomous miniaturized devices. We first summarise the technological advances in each field vs the current clinical practices and we conclude by merging the two worlds of traditional and digital biomarkers through AI/ML technologies to improve patient diagnosis and treatment. The fundamental role, limitations and prospects of AI in realizing this potential and enhancing the existing technologies to facilitate the development and clinical translation of "point-of-care" (POC) diagnostics is finally showcased.

Impact of Two Different Reference Measurement Procedures on Apparent System Accuracy of 18 CE-Marked Current-Generation Blood Glucose Monitoring Systems

BACKGROUND

Measurement accuracy has been assessed for many different blood glucose monitoring systems (BGMS) over the years by different study groups. However, the choice of the comparison measurement procedure may impact the apparent level of accuracy found in such studies.

MATERIALS AND METHODS

Measurement accuracy of 18 different BGMS was assessed in a setting based on ISO 15197 using two different comparison methods in parallel: a glucose oxidase (GOD)-based and a hexokinase (HK)-based method. Accuracy limits of ISO 15197 were applied, and additional analyses were performed, including bias, linear regression, and mean absolute relative difference (MARD) to assess the impact of possible differences between comparison methods on the apparent level of accuracy.

RESULTS

While ≈80% of BGMS met the accuracy criteria of ISO 15197 when compared with the respective manufacturers' reference measurement procedure, only two-thirds did so against both comparison methods. The mean relative bias ranged from -6.6% to +5.7% for the analysis against the GOD-based method and from -11.1% to +1.3% for the analysis against the HK-based method, whereas MARD results ranged from 3.7% to 9.8% and from 2.3% to 10.5%, respectively. Results of regression analysis showed slopes between 0.85 and 1.08 (GOD-based method) and between 0.81 and 1.01 (HK-based method).

CONCLUSIONS

The results of this study indicate that there are systematic differences between the reference measurement procedures used for BGMS calibration as well as for system accuracy assessment. Because of the potential impact on therapy of patients with diabetes resulting from these differences, further steps toward harmonization of the measurement procedures' results are important.

Glucose Concentrations from Continuous Glucose Monitoring Devices Compared to Those from Blood Plasma during an Oral Glucose Tolerance Test in Healthy Young Adults

Continuous glucose monitoring devices measure glucose in interstitial fluid. The devices are effective when used by patients with type 1 and 2 diabetes but are increasingly being used by researchers who are interested in the effects of various behaviours of glucose concentrations in healthy participants. Despite their more frequent application in this setting, the devices have not yet been validated for use under such conditions. A total of 124 healthy participants were recruited to a ten-day laboratory study. Each participant underwent four oral glucose tolerance tests, and a total of 3315 out of a possible 4960 paired samples were included in the final analysis. Bland-Altman plots and mean absolute relative differences were used to determine the agreement between the two methods. Bland-Altman analyses revealed that the continuous glucose monitoring devices had proportional bias (R = 0.028, p < 0.001) and a mean bias of -0.048 mmol/L, and device measurements were more variable as glucose concentrations increased. Ninety-nine per cent of paired values were in Zones A and B of the Parkes Error Grid plot, and there was an overall mean absolute relative difference of 16.2% (±15.8%). There was variability in the continuous glucose monitoring devices, and this variability was higher when glucose concentrations were higher. If researchers were to use continuous glucose monitoring devices to measure glucose concentrations during an oral glucose tolerance test in healthy participants, this variability would need to be considered.

Evidence From a Long-Term, Systematic Post-Market Surveillance Program: Clinical Performance of a Hematocrit-Insensitive Blood Glucose Test Strip

BACKGROUND

Described is a manufacturer's systematic post-market evaluation of the long-term clinical accuracy of a commercially available blood glucose monitoring (BGM) test strip product.

METHODS

Production batches of test strips were routinely and regularly sampled and evaluated in a clinical setting to assess product accuracy. Evaluations were performed on capillary blood samples from a minimum of 100 subjects with diabetes, by clinical staff according to instructions for use. Readings were compared against capillary blood samples collected at the same time and measured by a standard laboratory reference method. Clinical accuracy was calculated according to EN ISO 15197:2015.

RESULTS

A total of 21 115 paired results were obtained, equating to 209 production batches over the >3-year period since test strip launch. Of the results, 97.6% met the accuracy criterion (range: 97.1-98.1% by year), with 98.1% of values presenting zero risk as defined by the surveillance error grid. At the <5th (21.0-33.8%) and >95th (48.3-59.4%) percentile extremes of hematocrit distribution, 97.9% and 96.4% of values were clinically accurate. The product also demonstrated clinical accuracy across all seven glucose ranges ("bins") as defined by the standard. Under conditions of combined hematocrit and glucose (<80 mg/dL and ≥300 mg/dL) extremes, 97.7% of values were clinically accurate.

CONCLUSIONS

Methodologies and results from a manufacturer's self-imposed clinical accuracy surveillance program of a BGM product is presented. Given the publication of sometimes-conflicting data presented within ad hoc BGM clinical accuracy evaluations, usually of limited size, it is advocated that BGM manufacturers adopt similarly robust and systematic surveillance programs to safeguard patients.

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.

Seamless recording of glucometer measurements among older experienced diabetic patients - A study of perception and usability

Self-measurement and documentation of blood-glucose are critical elements of diabetes management, particularly in regimes including insulin. In this study, we analyze the usability of iBG-STAR, the first blood glucose meter connectable to a smartphone. This technology records glucometer measurements, removing the burden of documentation from diabetic patients. This study assesses the potential for implementation of iBG-STAR in routine care. Twelve long-term diabetic patients (4 males; median age of 66.5 years) were enrolled in the study. N = 4/12 reported diabetic polyneuropathy. Reported subjective mental workload for all tasks related to iBG-STAR was on average lower than 12 points, corresponding to the verbal code 'nearly no effort needed'. A "Post Study System Usability Questionnaire", evaluated the glucometer at an average value of 2.06 (SD = 1.02) on a 7-Likert-scale (1 = 'I fully agree' to 7 = 'I completely disagree') for usability. These results represent a positive user-experience. Patients with polyneuropathy may experience physical difficulties in completing the tasks, thereby affecting usability. Technologically savvy patients (n = 6) with a positive outlook on diabetes assessed the product as a suitable tool for themselves and would recommend to other diabetic patients. The main barrier to regular use was treating physicians' inability to retrieve digitally recorded data. This barrier was due to a shortcoming in interoperability of mobile devices and medical information systems.

Molecular enantiorecognition of l-glucose and d-glucose in whole blood samples

In the past years, enantioanalysis became very important for clinical analysis; biomarkers/substances of biomedical importance with chiral structure should be analyzed and their presence correlated with the specific disorder. Therefore, we developed a method for the assay of l- and d-glucose, based on molecular recognition of l- and d-glucose. While for d-glucose there are many methods to assess its quantity, the l-enantiomer is not routinely detected by standard methods. Two stochastic microsensors based on the immobilization of Copper(II)phthalocyanine and Ni(II)phthalocyanine, in natural diamond powder, were proposed for the enantioanalysis of glucose. The proposed methods proved to have high sensitivities and were able to be used for determination of concentrations as low as 2.5 pg mL^-1 for d-glucose and as low as 2.5 fg mL^-1 for l-glucose. The enatioanalysis was performed with good results in whole blood samples collected from diabetic patients.

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

BACKGROUND

The objective was to evaluate the performance (in terms of accuracy, precision, and trueness) of 5 CE-certified and commercially available blood glucose (BG) systems (meters plus test strips) using an innovative clinical-experimental study design with a 3-step glucose clamp approach and frequent capillary BG measurements.

METHODS

Sixteen subjects with type 1 diabetes participated in this open label, single center trial. BG was clamped at 3 levels for 60 minutes each: 60-100-200 mg/dL. Medical staff performed regular finger pricks (up to 10 per BG level) to obtain capillary blood samples for paired BG measurements with the 5 BG systems and a laboratory method as comparison.

RESULTS

Three BG systems displayed significantly lower mean absolute relative deviations (MARD) (ACCU-Chek® Aviva Nano [5.4%], BGStar® [5.1%], iBGStar® [5.3%]) than 2 others (FreeStyle InsuLinx® [7.7%], OneTouch Verio®IQ [10.3%]). The measurement precision of all BG systems was comparable, but relative bias was also lower for the 3 systems with lower MARD (ACCU-Chek [1.3%], BGStar [-0.9%], iBGStar [1.0%]) compared with the 2 others (FreeStyle [-7.2%], OneTouch [8.9%]).

CONCLUSIONS

This 3 range glucose clamp approach enables a systematic performance evaluation of BG systems under controlled and reproducible conditions. The random error of the tested BG systems was comparable, but some showed a lower systematic error than others. These BG systems allow an accurate glucose measurement at low, normal and high BG levels.

Brazilian multicenter study for the evaluation of patients' satisfaction of blood glucose self-monitoring with BGStar(®) blood glucose meter in insulinized patients with diabetes mellitus type 1 and 2

BACKGROUND

Diabetes mellitus (DM) is considered a global epidemic, and patient self-management education and support are critical in preventing and reducing the risk of complications. Self-monitoring of blood glucose (SMBG) is essential for care of individuals with DM, helping patients to achieve and maintain target blood glucose levels. The purpose of this study is to compare the satisfaction of insulinized DM patients on SMBG with use of investigational blood glucose meter (BGM) versus their routine device.

METHODS

A national, multicenter, open-label, phase 4 study was conducted on patients with type 1 or 2 DM under insulin therapy regimen, who were asked to use investigational BGM instead of their usual BGM device. The study was performed in 12 centers in Brazil for 12 weeks, with an extension period of 12 weeks. The primary endpoint was to measure the variation on the patients' level of satisfaction with investigational versus routine BGM, between visits, using a Visual Analogue Scale (VAS). Secondary endpoints addressed handling aspects, satisfaction, adherence and level of functionality and safety of investigational BGM.

RESULTS

The study included 292 patients (36.6 % DM1 and 63.4 % DM2), mean age 50.9 years old (±17.3 years), 57.5 % females. There was statistically significant improvement in global satisfaction with investigational BGM compared with routine BGM according to VAS [mean VAS score raised from 78.8 mm (SD = 18.0) to 90.8 mm (SD = 12.2) between visits]. After 12 weeks, level of satisfaction with investigational BGM according to questionnaires was superior to routine BGM regardless of age group (p < 0.001), type of DM (p < 0.001) or insulin regimen (p < 0.001). Investigational BGM was also regarded as safe, with 10 patients (3.4 %) reporting a total of 13 adverse events during the study.

CONCLUSIONS

Levels of satisfaction during SMBG were higher with use of investigational BGM and the device was deemed safe and easy to handle.

The Quantitative Relationship Between ISO 15197 Accuracy Criteria and Mean Absolute Relative Difference (MARD) in the Evaluation of Analytical Performance of Self-Monitoring of Blood Glucose (SMBG) Systems

The relationship between International Organization for Standardization (ISO) accuracy criteria and mean absolute relative difference (MARD), 2 methods for assessing the accuracy of blood glucose meters, is complex. While lower MARD values are generally better than higher MARD values, it is not possible to define a particular MARD value that ensures a blood glucose meter will satisfy the ISO accuracy criteria. The MARD value that ensures passing the ISO accuracy test can be described only as a probabilistic range. In this work, a Bayesian model is presented to represent the relationship between ISO accuracy criteria and MARD. Under the assumptions made in this work, there is nearly a 100% chance of satisfying ISO 15197:2013 accuracy requirements if the MARD value is between 3.25% and 5.25%.

Worldwide trends in diabetes since 1980: a pooled analysis of 751 population-based studies with 4.4 million participants

BACKGROUND

One of the global targets for non-communicable diseases is to halt, by 2025, the rise in the age-standardised adult prevalence of diabetes at its 2010 levels. We aimed to estimate worldwide trends in diabetes, how likely it is for countries to achieve the global target, and how changes in prevalence, together with population growth and ageing, are affecting the number of adults with diabetes.

METHODS

We pooled data from population-based studies that had collected data on diabetes through measurement of its biomarkers. We used a Bayesian hierarchical model to estimate trends in diabetes prevalence-defined as fasting plasma glucose of 7.0 mmol/L or higher, or history of diagnosis with diabetes, or use of insulin or oral hypoglycaemic drugs-in 200 countries and territories in 21 regions, by sex and from 1980 to 2014. We also calculated the posterior probability of meeting the global diabetes target if post-2000 trends continue.

FINDINGS

We used data from 751 studies including 4,372,000 adults from 146 of the 200 countries we make estimates for. Global age-standardised diabetes prevalence increased from 4.3% (95% credible interval 2.4-7.0) in 1980 to 9.0% (7.2-11.1) in 2014 in men, and from 5.0% (2.9-7.9) to 7.9% (6.4-9.7) in women. The number of adults with diabetes in the world increased from 108 million in 1980 to 422 million in 2014 (28.5% due to the rise in prevalence, 39.7% due to population growth and ageing, and 31.8% due to interaction of these two factors). Age-standardised adult diabetes prevalence in 2014 was lowest in northwestern Europe, and highest in Polynesia and Micronesia, at nearly 25%, followed by Melanesia and the Middle East and north Africa. Between 1980 and 2014 there was little change in age-standardised diabetes prevalence in adult women in continental western Europe, although crude prevalence rose because of ageing of the population. By contrast, age-standardised adult prevalence rose by 15 percentage points in men and women in Polynesia and Micronesia. In 2014, American Samoa had the highest national prevalence of diabetes (>30% in both sexes), with age-standardised adult prevalence also higher than 25% in some other islands in Polynesia and Micronesia. If post-2000 trends continue, the probability of meeting the global target of halting the rise in the prevalence of diabetes by 2025 at the 2010 level worldwide is lower than 1% for men and is 1% for women. Only nine countries for men and 29 countries for women, mostly in western Europe, have a 50% or higher probability of meeting the global target.

INTERPRETATION

Since 1980, age-standardised diabetes prevalence in adults has increased, or at best remained unchanged, in every country. Together with population growth and ageing, this rise has led to a near quadrupling of the number of adults with diabetes worldwide. The burden of diabetes, both in terms of prevalence and number of adults affected, has increased faster in low-income and middle-income countries than in high-income countries.

FUNDING

Wellcome Trust.

Technical and clinical accuracy of three blood glucose meters: clinical impact assessment using error grid analysis and insulin sliding scales

AIMS

Manufacturers of point-of-care testing (POCT) glucose systems must adhere to International Organisation for Standardisation (ISO) 15197 performance standards, a tightened version of which becomes mandatory in May 2016. Using methods deviating from the evaluation requirements of ISO 15197, we investigated the accuracy and clinical utility of three glucose testing systems.

METHODS

Whole blood glucose was measured on 62 EDTA-preserved samples with each system followed by plasma glucose determination with a laboratory hexokinase method. Technical accuracy was assessed using linear regression, Bland-Altman plots and bias. Clinical utility was evaluated using consensus error grid analysis and insulin dosing algorithms.

RESULTS

The correlation coefficient of the glucose measuring devices with the comparator method was between 0.979 and 0.993 (n=61). Bias against the reference method was +0.7-+4.4%. The FreeStyle Lite (0.7±4.4%) and ACCU-CHEK Aviva (1.3±7.3%) systems had the least bias to the reference. Error grid analysis depicts all meters to be clinically accurate, with all results falling within Zones A and B.

CONCLUSIONS

Conformité Européene-marked devices are presumed to have adequate accuracy, but postmarket evaluations are imperative to assess total system accuracy and whether regulatory targets are achieved.

The Performance and Usability of a Factory-Calibrated Flash Glucose Monitoring System

INTRODUCTION

The purpose of the study was to evaluate the performance and usability of the FreeStyle(®) Libre™ Flash glucose monitoring system (Abbott Diabetes Care, Alameda, CA) for interstitial glucose results compared with capillary blood glucose results.

MATERIALS AND METHODS

Seventy-two study participants with type 1 or type 2 diabetes were enrolled by four U.S. clinical sites. A sensor was inserted on the back of each upper arm for up to 14 days. Three factory-only calibrated sensor lots were used in the study. Sensor glucose measurements were compared with capillary blood glucose (BG) results (approximately eight per day) obtained using the BG meter built into the reader (BG reference) and with the YSI analyzer (Yellow Springs Instrument, Yellow Springs, OH) reference tests at three clinic visits (32 samples per visit). Sensor readings were masked to the participants.

RESULTS

The accuracy of the results was demonstrated against capillary BG reference values, with 86.7% of sensor results within Consensus Error Grid Zone A. The percentage of readings within Consensus Error Grid Zone A on Days 2, 7, and 14 was 88.4%, 89.2%, and 85.2%, respectively. The overall mean absolute relative difference was 11.4%. The mean lag time between sensor and YSI reference values was 4.5±4.8 min. Sensor accuracy was not affected by factors such as body mass index, age, type of diabetes, clinical site, insulin administration, or hemoglobin A1c.

CONCLUSIONS

Interstitial glucose measurements with the FreeStyle Libre system were found to be accurate compared with capillary BG reference values, with accuracy remaining stable over 14 days of wear and unaffected by patient characteristics.

Accuracy Evaluation of Four Blood Glucose Monitoring Systems in Unaltered Blood Samples in the Low Glycemic Range and Blood Samples in the Concentration Range Defined by ISO 15197

INTRODUCTION

Systems for self-monitoring of blood glucose (SMBG) are expected to be accurate enough to provide reliable measurement results. Especially in the low glycemic range, adequate therapeutic decisions based on reliable results can alleviate complications associated with hypoglycemia.

MATERIALS AND METHODS

The accuracy of four SMBG systems (system 1 was the ACCU-CHEK(®) Aviva [Roche Diagnostics GmbH, Mannheim, Germany], system 2 was the Contour(®) XT [Bayer Consumer Care AG, Basel, Switzerland], system 3 was the GlucoCheck XL [aktivmed GmbH, Augsberg, Germany], and system 4 was the GlucoMen(®) LX PLUS [A. Menarini Diagnostics S.r.l., Florence, Italy]) with three test-strip lots each was evaluated by calculating mean absolute relative differences (MARDs). Two datasets were evaluated: (1) 100 samples with blood glucose concentrations <70 mg/dL and (2) 100 samples distributed following International Organization for Standardization (ISO) standard 15197. Each sample was measured twice with each test-strip lot of each SMBG system. Comparison measurement results were obtained with a glucose oxidase method and a hexokinase method, both traceable according to ISO 17511. Analysis of variance of the MARD between the SMBG system and the comparison method was performed.

RESULTS

MARD values ranged from 4.4% to 13.4% (<70 mg/dL) and 4.8% to 8.9% (ISO 15197-distributed) and differed significantly, with systems 1 and 2 showing lower MARDs than systems 3 and 4. MARD values deviated by up to 2.5% (corresponding to a relative deviation of approximately 40%) between the two comparison methods.

CONCLUSIONS

The investigated SMBG systems showed a significant variation of accuracy (measured by MARD), especially with higher MARD values in the low glycemic range. The selected comparison method had an impact on the MARD and therefore on the apparent accuracy of the SMBG systems. Sufficient measurement accuracy in the low glycemic range is required to enable users to react adequately to hypoglycemia.

A comprehensive evaluation of strip performance in multiple blood glucose monitoring systems

Accurate self-monitoring of blood glucose is a key component of effective self-management of glycemic control. Accurate self-monitoring of blood glucose results are required for optimal insulin dosing and detection of hypoglycemia. However, blood glucose monitoring systems may be susceptible to error from test strip, user, environmental and pharmacological factors. This report evaluated 5 blood glucose monitoring systems that each use Verio glucose test strips for precision, effect of hematocrit and interferences in laboratory testing, and lay user and system accuracy in clinical testing according to the guidelines in ISO15197:2013(E). Performance of OneTouch(®) VerioVue™ met or exceeded standards described in ISO15197:2013 for precision, hematocrit performance and interference testing in a laboratory setting. Performance of OneTouch(®) Verio IQ™, OneTouch(®) Verio Pro™, OneTouch(®) Verio™, OneTouch(®) VerioVue™ and Omni Pod each met or exceeded accuracy standards for user performance and system accuracy in a clinical setting set forth in ISO15197:2013(E).

Quality of HbA1c Measurement in the Practice: The German Perspective

Hemoglobin A1c (HbA1c) measurement has come to be a cornerstone in modern diabetes therapy. However, the methodological aspects of this type of measurement have been given little attention lately due to its position as an established method of choice. Nevertheless, quite a number of issues face practical application, such as clinically relevant differences between different measurement methods--both lab-based and point-of-care (POCT) systems will show better or worse diabetes management results after switching methods; and there are a number of possible reasons that need to be known and observed in practice. The aim of this review is to draw attention to these problems from a German point of view and provide suggestions for appropriate measures to improve the situation.

Glucose: Detection and analysis

Glucose is an aldosic monosaccharide that is centrally entrenched in the processes of photosynthesis and respiration, serving as an energy reserve and metabolic fuel in most organisms. As both a monomer and as part of more complex structures such as polysaccharides and glucosides, glucose also plays a major role in modern food products, particularly where flavor and or structure are concerned. Over the years, many diverse methods for detecting and quantifying glucose have been developed; this review presents an overview of the most widely employed and historically significant, including copper iodometry, HPLC, GC, CZE, and enzyme based systems such as glucose meters. The relative strengths and limitations of each method are evaluated, and examples of their recent application in the realm of food chemistry are discussed.

Accuracy of blood glucose meters for self-monitoring affects glucose control and hypoglycemia rate in children and adolescents with type 1 diabetes

AIMS/HYPOTHESIS

This study investigated the accuracy of blood glucose meters for self-monitoring and its influence on glycated hemoglobin (HbA1c) levels and the frequency of hypoglycemic coma.

MATERIALS AND METHODS

Self-measured and simultaneously obtained laboratory blood glucose values from 9,163 patients with type 1 diabetes <18 years of age in the German/Austrian Diabetes Prospective Documentation Initiative registry were analyzed by investigating their compliance with the International Organization for Standardization (ISO) criteria (versions 2003 and 2013) and by error grid analyses. Regression models elucidated effects on glucose control and hypoglycemia rates.

RESULTS

Depending on the respective subgroup (defined by sex, age, duration of diabetes, mode of insulin therapy), 78.7-94.7% of the self-monitoring of blood glucose (SMBG) values met the old and 79.7-88.6% met the new ISO criteria. In Clarke and Parkes error grid analyses, the percentages of SMBG values in Zone A ranged between 92.8% and 94.6% (Clarke) and between 92.2% and 95.0% (Parkes). The patient group with SMBG devices measuring "far too low" (compared with the laboratory-obtained glucose levels) presented with a higher HbA1c level than those measuring "far too high," "too high," "identical/almost identical," or "too low" (based on quintiles of deviation). Performing "far too high" was associated with the highest rate of hypoglycemic coma in comparison with the other deviation quintiles.

CONCLUSIONS

This study showed that current SMBG devices fulfilled neither the previous nor the new ISO criteria. Large deviations of the SMBG values from the "true" glucose levels resulted in higher HbA1c levels and markedly increased rates of hypoglycemic events.

The impact of measurement frequency on the domains of glycemic control in the critically ill--a Monte Carlo simulation

The role of blood glucose (BG) measurement frequency on the domains of glycemic control is not well defined. This Monte Carlo mathematical simulation of glycemic control in a cohort of critically ill patients modeled sets of 100 patients with simulated BG-measuring devices having 5 levels of measurement imprecision, using 2 published insulin infusion protocols, for 200 hours, with 3 different BG-measurement intervals-15 minutes (Q15'), 1 hour (Q1h), and 2 hours (Q2h)-resulting in 1,100,000 BG measurements for 3000 simulated patients. The model varied insulin sensitivity, initial BG value and rate of gluconeogenesis. The primary outcomes included rates of hyperglycemia (BG > 180 mg/dL), hypoglycemia (BG < 70 and 40 mg/dL), proportion of patients with elevated glucose variability (within-patient coefficient of variation [CV] > 20%), and time in range (BG ranges 80-150 mg/dL and 80-180 mg/dL). Percentages of hyperglycemia, hypoglycemia at both thresholds, and patients with elevated glucose variability as well as time outside glycemic targets were substantially higher in simulations with measurement interval Q2h compared to those with measurement interval Q1h and moderately higher in simulations with Q1h than in those with Q15'. Higher measurement frequency mitigated the deleterious effect of high measurement imprecision, defined as CV ≥ 15%. This Monte Carlo simulation suggests that glycemic control in critically ill patients is more optimal with a BG measurement interval no longer than 1h, with further benefit obtained with use of measurement interval of 15'. These findings have important implications for the development of glycemic control standards.

Accuracy evaluation of contour next compared with five blood glucose monitoring systems across a wide range of blood glucose concentrations occurring in a clinical research setting

BACKGROUND

This study evaluated the accuracy of Contour(®) Next (CN; Bayer HealthCare LLC, Diabetes Care, Whippany, NJ) compared with five blood glucose monitoring systems (BGMSs) across a wide range of clinically occurring blood glucose levels.

SUBJECTS AND METHODS

Subjects (n=146) were ≥ 18 years and had type 1 or type 2 diabetes. Subjects' glucose levels were safely lowered or raised to provide a wide range of glucose values. Capillary blood samples were tested on six BGMSs and a YSI glucose analyzer (YSI Life Sciences, Inc., Yellow Springs, OH) as the reference. Extreme glucose values were achieved by glucose modification of the blood sample. System accuracy was assessed by mean absolute difference (MAD) and mean absolute relative difference (MARD) across several glucose ranges, with <70 mg/dL evaluated by MAD as the primary end point.

RESULTS

In the low glucose range (<70 mg/dL), MAD values were as follows: Accu-Chek(®) Aviva Nano (Roche Diagnostics, Indianapolis, IN), 3.34 mg/dL; CN, 2.03 mg/dL; FreeStyle Lite(®) (FSL; Abbott Diabetes Care, Inc., Alameda, CA), 2.77 mg/dL; OneTouch(®) Ultra(®) 2 (LifeScan, Inc., Milpitas, CA), 10.20 mg/dL; OneTouch(®) Verio(®) Pro (LifeScan, Inc.), 4.53 mg/dL; and Truetrack(®) (Nipro Diagnostics, Inc., Fort Lauderdale, FL), 11.08 mg/dL. The lowest MAD in the low glucose range, from CN, was statistically significantly lower than those of the other BGMSs with the exception of the FSL. CN also had a statistically significantly lower MARD than all other BGMSs in the low glucose range. In the overall glucose range (21-496 mg/dL), CN yielded the lowest MAD and MARD values, which were statistically significantly lower in comparison with the other BGMSs.

CONCLUSIONS

When compared with other BGMSs, CN demonstrated the lowest mean deviation from the reference value (by MAD and MARD) across multiple glucose ranges.

System accuracy evaluation of the GlucoRx nexus voice TD-4280 blood glucose monitoring system

Use of blood glucose (BG) meters in the self-monitoring of blood glucose (SMBG) significantly lowers the risk of diabetic complications. With several BG meters now commercially available, the International Organization for Standardization (ISO) ensures that each BG meter conforms to a set degree of accuracy. Although adherence to ISO guidelines is a prerequisite for commercialization in Europe, several BG meters claim to meet the ISO guidelines yet fail to do so on internal validation. We conducted a study to determine whether the accuracy of the GlucoRx Nexus TD-4280 meter, utilized by our department for its cost-effectiveness, complied with ISO guidelines. 105 patients requiring laboratory blood glucose analysis were randomly selected and reference measurements were determined by the UniCel DxC 800 clinical system. Overall the BG meter failed to adhere to the ≥95% accuracy criterion required by both the 15197:2003 (overall accuracy 92.4%) and 15197:2013 protocol (overall accuracy 86.7%). Inaccurate meters have an inherent risk of over- and/or underestimating the true BG concentration, thereby risking patients to incorrect therapeutic interventions. Our study demonstrates the importance of internally validating the accuracy of BG meters to ensure that its accuracy is accepted by standardized guidelines.

Performance of blood glucose meters in compliance with current and future clinical ISO15197 accuracy criteria

Since 2003, blood glucose meters for patient self testing are approved in Europe based on the accuracy performance criteria as defined by the ISO15197 guideline. A new draft ISO guideline is currently under regulatory review, which suggests more strict accuracy acceptance criteria, and which may not be entirely fulfilled by currently commercialized blood glucose meter systems. In order to investigate the compliance of BG*Star and iBG*Star and several other blood glucose meters with the new draft ISO guideline, we performed a post-hoc analysis of data obtained from a recently performed ISO-conforming clinical accuracy performance study. This study was performed with 106 patients, clinically presenting with blood glucose levels distributed over the entire measurement range and in line with the glucose distribution requirements as demanded by the guideline. The YSI 2300 STAT Plus analyzer (glucose oxidase) served as reference method. While all tested meters had been in a high degree of compliance with the current ISO criteria, performance was lower when analyzed in accordance with the new acceptance criteria (95% of readings have to be within ±15 mg/dL for values <100 mg/dL, and within ±15% for values ≥100 mg/dL). The following meters met the new criteria: Accu-Chek Aviva (95.5%/98.6%), BG*Star (98.5%/97.3%), iBG*Star (98.5%/97.3%), FreeStyle Freedom Lite (95.5%/96.6%), and OneTouch Ultra2 (95.5%/96.5%). One meter failed with low blood glucose values (Contour: 90.9%/95.9%). In conclusion, BG*Star and iBG*Star and several other branded meters met the new draft ISO15197 acceptance criteria, when tested in accordance with the instructions for use and with the ISO accuracy testing protocol in a clinical setting.

Evaluation of 12 blood glucose monitoring systems for self-testing: system accuracy and measurement reproducibility

BACKGROUND

Systems for self-monitoring of blood glucose (SMBG) have to provide accurate and reproducible blood glucose (BG) values in order to ensure adequate therapeutic decisions by people with diabetes.

MATERIALS AND METHODS

Twelve SMBG systems were compared in a standardized manner under controlled laboratory conditions: nine systems were available on the German market and were purchased from a local pharmacy, and three systems were obtained from the manufacturer (two systems were available on the U.S. market, and one system was not yet introduced to the German market). System accuracy was evaluated following DIN EN ISO (International Organization for Standardization) 15197:2003. In addition, measurement reproducibility was assessed following a modified TNO (Netherlands Organization for Applied Scientific Research) procedure. Comparison measurements were performed with either the glucose oxidase method (YSI 2300 STAT Plus™ glucose analyzer; YSI Life Sciences, Yellow Springs, OH) or the hexokinase method (cobas(®) c111; Roche Diagnostics GmbH, Mannheim, Germany) according to the manufacturer's measurement procedure.

RESULTS

The 12 evaluated systems showed between 71.5% and 100% of the measurement results within the required system accuracy limits. Ten systems fulfilled with the evaluated test strip lot minimum accuracy requirements specified by DIN EN ISO 15197:2003. In addition, accuracy limits of the recently published revision ISO 15197:2013 were applied and showed between 54.5% and 100% of the systems' measurement results within the required accuracy limits. Regarding measurement reproducibility, each of the 12 tested systems met the applied performance criteria.

CONCLUSIONS

In summary, 83% of the systems fulfilled with the evaluated test strip lot minimum system accuracy requirements of DIN EN ISO 15197:2003. Each of the tested systems showed acceptable measurement reproducibility. In order to ensure sufficient measurement quality of each distributed test strip lot, regular evaluations are required.

Technology to optimize pediatric diabetes management and outcomes

Technology for diabetes management is rapidly developing and changing. With each new development, there are numerous factors to consider, including medical benefits, impact on quality of life, ease of use, and barriers to use. It is also important to consider the interaction between developmental stage and technology. This review considers a number of newer diabetes-related technologies and explores issues related to their use in the pediatric diabetes population (including young adults), with a focus on psychosocial factors. Areas include trend technology in blood glucose monitoring, continuous glucose monitoring, sensor-augmented insulin pumps and low glucose suspend functions, internet applications including videoconferencing, mobile applications (apps), text messaging, and online gaming.

Blood glucose meters employing dynamic electrochemistry are stable against hematocrit interference in a laboratory setting

BACKGROUND

Hematocrit (HCT) is known to be a confounding factor that interferes with many blood glucose (BG) measurement technologies, resulting in wrong readings. Dynamic electrochemistry has been identified as one possible way to correct for these potential deviations. The purpose of this laboratory investigation was to assess the HCT stability of four BG meters known to employ dynamic electrochemistry (BGStar and iBGStar, Sanofi; Wavesense Jazz, AgaMatrix; Wellion Linus, MedTrust) in comparison with three other devices (GlucoDock, Medisana; OneTouch Verio Pro, LifeScan; FreeStyle Freedom InsuLinx, Abbott-Medisense).

METHODS

Venous heparinized blood was immediately aliquoted after draw and manipulated to contain three different BG concentrations (60-90, 130-160, and 280-320 mg/dl) and five different HCT levels (25%, 35%, 45%, 55%, and 60%). After careful oxygenation to normal blood oxygen pressure, each of the resulting 15 different samples was measured six times with three devices and three strip lots of each meter. The YSI Stat 2300 served as laboratory reference method. Stability to HCT influence was assumed when less than 10% difference occurred between the highest and lowest mean glucose deviations in relation to HCT concentrations [hematocrit interference factor (HIF)].

RESULTS

Five of the investigated self-test meters showed a stable performance with the different HCT levels tested in this investigation: BGStar (HIF 4.6%), iBGStar (6.6%), Wavesense Jazz (4.1%), Wellion Linus (8.5%), and OneTouch Verio Pro (6.2%). The two other meters were influenced by HCT (FreeStyle InsuLinx 17.8%; GlucoDock 46.5%).

CONCLUSIONS

In this study, meters employing dynamic electrochemistry, as used in the BGStar and iBGStar devices, were shown to correct for potential HCT influence on the meter results. Dynamic electrochemistry appears to be an effective way to handle this interfering condition.

Evaluation of the effects of insufficient blood volume samples on the performance of blood glucose self-test meters

BACKGROUND

Accuracy of blood glucose readings is (among other things) dependent on the test strip being completely filled with sufficient sample volume. The devices are supposed to display an error message in case of incomplete filling. This laboratory study was performed to test the performance of 31 commercially available devices in case of incomplete strip filling.

METHODS

Samples with two different glucose levels (60-90 and 300-350 mg/dl) were used to generate three different sample volumes: 0.20 µl (too low volume for any device), 0.32 µl (borderline volume), and 1.20 µl (low but supposedly sufficient volume for all devices). After a point-of-care capillary reference measurement (StatStrip, NovaBiomedical), the meter strip was filled (6x) with the respective volume, and the response of the meters (two devices) was documented (72 determinations/meter type). Correct response was defined as either an error message indicating incomplete filling or a correct reading (±20% compared with reference reading).

RESULTS

Only five meters showed 100% correct responses [BGStar and iBGStar (both Sanofi), ACCU-CHEK Compact+ and ACCU-CHEK Mobile (both Roche Diagnostics), OneTouch Verio (LifeScan)]. The majority of the meters (17) had up to 10% incorrect reactions [predominantly incorrect readings with sufficient volume; Precision Xceed and Xtra, FreeStyle Lite, and Freedom Lite (all Abbott); GlucoCard+ and GlucoMen GM (both Menarini); Contour, Contour USB, and Breeze2 (all Bayer); OneTouch Ultra Easy, Ultra 2, and Ultra Smart (all LifeScan); Wellion Dialog and Premium (both MedTrust); FineTouch (Terumo); ACCU-CHEK Aviva (Roche); and GlucoTalk (Axis-Shield)]. Ten percent to 20% incorrect reactions were seen with OneTouch Vita (LifeScan), ACCU-CHEK Aviva Nano (Roche), OmniTest+ (BBraun), and AlphaChek+ (Berger Med). More than 20% incorrect reactions were obtained with Pura (Ypsomed), GlucoCard Meter and GlucoMen LX (both Menarini), Elite (Bayer), and MediTouch (Medisana).

CONCLUSIONS

In summary, partial and incomplete blood filling of glucose meter strips is often associated with inaccurate reading. These findings underline the importance of appropriate patient education on this aspect of blood glucose self-monitoring.

The precision study: examining the inter- and intra-assay variability of replicate measurements of BGStar, iBGStar and 12 other blood glucose monitors

OBJECTIVE

Self-monitoring of blood glucose is a key element in diabetes management. Accurate and precise performance of blood glucose monitors (BGMs) ensures that valid values are obtained to guide treatment decisions by patients and physicians. BGStar and iBGStar are hand-held BGMs that use dynamic electrochemistry to correct for potential interferences and thereby minimize system errors.

RESEARCH DESIGN AND METHODS

A single-center, in vitro diagnostic device performance evaluation with heparinized oxygenated venous blood samples (intra-assay precision) and control solutions (interassay precision) was performed in a laboratory setting, comparing BGStar and iBGStar with 12 competitors.

MAIN OUTCOME MEASURES

The primary outcome was the coefficient of variation percent (CV%) of the BGMs investigated.

RESULTS

In inter-assay precision analyses, all but GlucoMen LX had a CV <5%, and in intra-assay precision analyses, 10 of the 14 devices tested had CV <5%. BGStar and iBGStar had a CV <5% in both the inter- and intra-assay precision analyses. The smallest variation was found in the near-normoglycemic glucose range (5.3 - 8.0 mmol/l) for both BGStar and iBGStar in the inter-assay precision analysis.

CONCLUSIONS

BGStar and iBGStar were proven to have very good inter-assay and high intra-assay precision, demonstrating low scattering of replicate measurements with both clinical samples and control solutions.

Evidence for long-term impact of Pasos Adelante: using a community-wide survey to evaluate chronic disease risk modification in prior program participants

Effective community-level chronic disease prevention is critical to population health within developed and developing nations. Pasos Adelante is a preventive intervention that aims to reduce chronic disease risk with evidence of effectiveness in US-Mexico residing, Mexican origin, participants. This intervention and related ones also implemented with community health workers have been shown to improve clinical, behavioral and quality of life indicators; though most evidence is from shorter-term evaluations and/or lack comparison groups. The current study examines the impact of this program using secondary data collected in the community 3-6 years after all participants completed the program. A proportional household survey (N = 708) was used that included 48 respondents who indicated they had participated in Pasos. Using propensity score matching to account for differences in program participants versus other community residents (the program targeted those with diabetes and associated risk factors), 148 natural controls were identified for 37 matched Pasos participants. Testing a range of behavioral and clinical indicators of chronic disease risk, logistic regression models accounting for selection bias showed two significant findings; Pasos participants were more physically active and drank less whole milk. These findings add to the evidence of the effectiveness of Pasos Adalente and related interventions in reducing chronic disease risk in Mexican-origin populations, and illustrate the use of innovative techniques for using secondary, community-level data to complement prior evaluation research.

System accuracy of blood glucose monitoring systems: impact of use by patients and ambient conditions

For self-monitoring of blood glucose by people with diabetes, the reliability of the measured blood glucose values is a prerequisite in order to ensure correct therapeutic decisions. Requirements for system accuracy are defined by the International Organization for Standardization (ISO) in the standard EN ISO 15197:2003. However, even a system with high analytical quality is not a guarantee for accurate and reliable measurement results. Under routine life conditions, blood glucose measurement results are affected by several factors. First, the act of performing measurements as well as the handling of the system may entail numerous possible error sources, such as traces of glucose-containing products on the fingertips, the use of deteriorated test strips, or the incorrect storage of test strips. Second, ambient and sampling conditions such as high altitude, partial pressure of oxygen, ambient temperature, and the use of alternate test sites can have an influence on measurement results. Therefore, the user-friendliness of a system and the quality of the manufacturer's labeling to reduce the risk of handling errors are also important aspects in ensuring reliable and accurate measurement results. In addition, the analytical performance of systems should be less prone to user errors and ambient conditions. Finally, people with diabetes must be aware of the information and instructions in the manufacturer's labeling and must be able to measure and interpret blood glucose results correctly.

Blood‐Glucose Biosensors, Development and Challenges

Diabetes mellitus is one of the major causes of premature illness and death worldwide. The World Health Organization estimated that by 2030, 439 million people, corresponding to 7.8% of the world adult population, will live with diabetes. With an increasing diabetic population, a Blood Glucose Monitoring System (BGMS) is becoming an ever important tool for diabetes management. The history of blood biosensor development can be traced back to 1932, when Warburg and Christian reported the “yellow enzyme” from yeast changed to colorless upon oxidizing its substrate and resumed the yellow color after its oxidation by oxygen. Since then a lot of research and development has taken place on blood glucose sensors, and the biosensor technology has gone through three generations, with the current commercially available BGMS predominantly relies on the second generation of technology. The advantages and challenges of each generation are discussed. This chapter will examine in detail topics covering the areas of electrode substrate and electrode material selection, fluid detection electrode, reaction chamber, chemistry (electrolyte, polymer, enzyme and mediator), detection method, analytical performance, regulatory requirements and the manufacturing process. The chapter will close with the clinical utility and future direction and application of glucose biosensor include a brief introduction to the Continuous Blood Glucose Monitoring System (CGMS).

Analysis of "Accuracy evaluation of five blood glucose monitoring systems: the North American comparator trial"

In an article in Journal of Diabetes Science and Technology, Halldorsdottir and coauthors examined the accuracy of five blood glucose monitoring systems (BGMSs) in a study sponsored by the manufacturer of the BGMS CONTOUR NEXT EZ (EZ) and found that this BGMS was the most accurate one. However, their findings must be viewed critically given that one of the BGMSs (ACCU-CHEK Aviva) was not compared against the reference measurement specified by its manufacturer, thus making it likely that it performed suboptimally. Also, the accuracy of the glucose-oxidase-based ONE TOUCH Ultra2 and TRUEtrack BGMS is likely to have been underestimated because of the expected low oxygen level in the glycolysed blood samples used to test the performance of these BGMSs under hypoglycemic conditions. In conclusion, although this study shows that EZ is an accurate BGMS, comparisons between this and other BGMSs should be interpreted with caution.

Technical aspects of the Parkes error grid

BACKGROUND

The Parkes error grid, which was developed in 1994, presented performance zones for blood glucose (BG) monitors with borders that were not mathematically specified at the time the grid was published.

METHODS

In this article, we (1) review the history of the Parkes error grid, (2) present the never-before-published exact coordinates and specifications of the grid so that others may produce an exact replica of the original grid, and (3) discuss our suggestions how this metric should be applied.

RESULTS

The new ISO15197:2013 guideline for system accuracy assessment of BG meters for patient self-measurement incorporates use of this metric for defining acceptable accuracy of BG monitors. It is expected that, for regulatory purposes, this document will stipulate that the error grid version for type 1 diabetes should be applied with the caveat that only the A zone represents acceptable accuracy.

CONCLUSIONS

It remains to be seen by how much the new error grid, which is currently being developed by the Food and Drug Administration/Diabetes Technology Society/American Diabetes Association/The Endocrine Society/Association for Advancement of Medical Instrumentation, will deviate from the Parkers error grid.

Accuracy evaluation of five blood glucose monitoring systems: the North American comparator trial

BACKGROUND

This study evaluated differences in accuracy between the CONTOUR® NEXT EZ (EZ) blood glucose monitoring system (BGMS) and four other BGMSs [ACCU-CHEK® Aviva (ACAP), FreeStyle Freedom Lite® (FFL), ONE TOUCH® Ultra®2 (OTU2), and TRUEtrack® (TT)].

METHODS

Up to three capillary blood samples (N = 393) were collected from 146 subjects with and without diabetes. One sample per subject was tested with fresh (natural) blood; the other samples were glycolyzed to lower blood glucose to <70 mg/dl. Meter results were compared with results from plasma from the same sample tested on a Yellow Springs Instruments (YSI) 2300 STAT PlusTM glucose analyzer. Blood glucose monitoring system accuracy was compared using mean absolute relative difference (MARD; from laboratory reference method results) and other analyses. Separate analyses on fresh (natural) samples only were conducted to determine potential effects of glycolysis on MARD values of systems utilizing glucose-oxidase-based test strip chemistry.

RESULTS

Across the tested glucose range, the EZ had the lowest MARD of 4.7%; the ACAP, FFL, OTU2, and TT had MARD values of 6.3%, 18.3%, 23.4%, and 26.2%, respectively. For samples with glucose concentrations <70 mg/dl, the EZ had the lowest MARD (0.65%), compared with the ACAP (2.5%), FFL (18.3%), OTU2 (22.4%), and TT (33.2%) systems.

CONCLUSIONS

The EZ had the lowest MARD across the tested glucose ranges when compared with four other BGMSs when all samples were analyzed as well as when natural samples only were analyzed.

Investigating social ecological contributors to diabetes within Hispanics in an underserved U.S.-Mexico border community

Hispanics bear a disproportionate burden of diabetes in the United States, yet relations of structural, socio-cultural and behavioral factors linked to diabetes are not fully understood across all of their communities. The current study examines disparities and factors associated with diabetes in adult Hispanics of Mexican-descent (N = 648) participating in a population survey of an underserved rural U.S.-Mexico border community. The overall rate of diabetes prevalence rate in the sample, based on self-report and a glucose testing, was 21%; much higher than rates reported for U.S. adults overall, for all Hispanic adults, or for Mexican American adults specifically. Acculturation markers and social determinants of health indicators were only significantly related to diabetes in models not accounting for age. Older age, greater BMI (>30), greater waist-to-hip ratio as well as lower fruit and vegetable consumption were significantly related to increased likelihood of diabetes when all structural, cultural, behavioral, and biological factors were considered. Models with sets of behavioral factors and biological factors each significantly improved explanation of diabetes relative to prior social ecological theory-guided models. The findings show a critical need for diabetes prevention efforts in this community and suggest that health promotion efforts should particularly focus on increasing fruit and vegetable consumption.

Do currently available blood glucose monitors meet regulatory standards? 1-day public meeting in Arlington, Virginia

Blood glucose monitors (BGMs) are approved by regulatory agencies based on their performance during strict testing conducted by their manufacturers. However, after approval, there is uncertainty whether BGMs maintain the accuracy levels that were achieved in the initial data. The availability of inaccurate BGM systems pose a public health problem because their readings serve as a basis for treatment decisions that can be incorrect. Several articles have concluded that BGMs in the marketplace may not consistently provide accurate results in accordance with the regulatory standards that led to approval. To address this growing concern, Diabetes Technology Society organized and conducted a 1-day public meeting on May 21, 2013, in Arlington, VA, presided by its president, David Klonoff, M.D., FACP, Fellow AIMBE, to determine whether BGMs on the market meet regulatory standards. The meeting consisted of four sessions in which Food and Drug Administration diabetes experts as well as leading academic clinicians and clinical chemists participated: (1) How is BGM performance determined? (2) Do approved BGMs perform according to International Organization for Standardization standards? (3) How do approved BGMs perform when used by patients and health care professionals? (4) What could be the consequence of poor BGM performance?

Considerations for an institution for evaluation of diabetes technology devices to improve their quality in the European Union

All medical devices used for self-monitoring of blood glucose (BG), insulin injection, continuous subcutaneous insulin infusion, and continuous glucose monitoring in the European Union (EU) must have a Communauté Européenne (CE) mark. However, the approval process for obtaining this mark is different from that used by the European Medicines Agency in the EU for drugs or by the Food and Drug Administration in the United States for such medical and in vitro diagnostic devices. The notified bodies involved in the CE mark process perform this evaluation in cooperation with the manufacturers. They have only limited diabetes know-how; they have to handle all kinds of medical devices. There are devices for therapy on the market in the EU (i.e., they have market approval) that do not fulfill quality requirements, as indicated, for example, in the international norm ISO 15197 for BG test systems. Evaluation of the performance of such systems is usually provided by the manufacturers. What is missing in the EU is an independent institution that performs regular and critical evaluation of the quality of devices used for diabetes therapy before and also after their market approval. The work of such an institution would focus on BG test systems (these represent two-thirds of the market of medical devices for diabetes treatment) but would also evaluate the performance of other devices. It has to be clarified what legal framework is required for such an institution and how it can be financed; probably this can be done in a shared manner by the manufacturers of such devices and the health insurance companies. Positive evaluation results should be a prerequisite prior to any reimbursement for such devices.

Variability of blood glucose meters for patient self-testing: analysis of the article by Brazg and coauthors

The article by Brzag and coauthors in this issue of Journal of Diabetes Science and Technology reports a competitive accuracy performance study for a branded meter in comparison with six low-cost meters currently available in the United States. It highlights several important topics: (1) the need for more stringent post-marketing requirements for blood glucose meters after launch and (2) low-cost meters use older technologies and their manufacturers do not usually seriously invest in new technology or constant quality assurance efforts. This may explain the study results, which show superior performance of the branded meter. Finally, the article pinpoints to the "quality versus price" dilemma faced by the prescribing physician and their patients in daily routine, which may be additionally aggravated by budget constraints and prescription rules in reimbursed markets.

Determination of hematocrit interference in blood samples derived from patients with different blood glucose concentrations

BACKGROUND

We performed a blood glucose meter hematocrit (HCT) interference test with lower sample manipulation requirements by using blood samples from patients with different blood glucose (BG) levels.

METHODS

Blood from five patients with different BG levels (2.8, 5.6, 8.3, 13.9, 19.4 mmol/liter) was manipulated to contain five different HCT concentrations (35/40/45/50/55%). Each sample was measured three times in parallel with 14 BG testing devices (reference method: YSI 2300 STAT Plus™ Glucose Analyzer). The largest mean deviations in both directions from the reference method (normalized to 100% at 45% HCT) were added as a measure for hematocrit interference factor (HIF). A HIF >10% was considered to represent clinically relevant HCT interference.

RESULTS

Few devices showed no clinically relevant HCT interference at high/low BG levels: BGStar® (7.2%, 7.3%), iBGStar® (9.0%, 8.6%), Contour® (10.0%, 4.6%), OneTouch® Verio™ 2 (10.0%, 5.2%), and GlucoMen® LX (7.2%, 5.1%). Other devices showed interference at one or both glucose ranges: ACCU-CHEK® Aviva (12.6%, 10.7%), Aviva Nano (7.2%, 10.5%), Breeze2 (3.6%, 30.2%), GlucoCard G+ (12.6%, 7.0%), OneTouch® Ultra®2 (12.6%, 25.6%), FreeStyle Freedom Lite® (9.0%, 11.0%), Precision Xceed (16.2%, 15.3%), and MediTouch® (19.8%, 28.0%). The deviations in all devices were less pronounced in the HCT range of 35-50%.

CONCLUSIONS

The results of this trial with less sample manipulation (HCT only) confirmed previous examinations with HCT and glucose manipulation. The same devices showed HCT stability as previously observed. Artificial sample manipulation may be less crucial than expected when evaluating HCT interference.

System accuracy evaluation of 43 blood glucose monitoring systems for self-monitoring of blood glucose according to DIN EN ISO 15197

BACKGROUND

The accuracy of systems for self-monitoring of blood glucose is important, as reliable measurement results are a prerequisite for therapeutic decisions.

METHODS

This system accuracy evaluation study was performed according to DIN EN ISO 15197:2003 for 43 Conformité Européenne (CE)-labeled blood glucose (BG) monitoring systems. Measurement results of each system were compared with results of the designated comparison method (manufacturer's measurement procedure): glucose oxidase method (YSI 2300 glucose analyzer) or hexokinase method (Hitachi 917/ cobas 501).

RESULTS

Complete assessment according to the International Organization for Standardization (ISO) standard was performed for 34 out of 43 systems, and 27 (79.4%) meet the requirements of the standard, i.e., ≥95% of their results showed at least the minimum acceptable accuracy. For 9 of the 43 systems, complete accuracy assessment was not performed due to an oxygen sensitivity (manufacturer's labeling). The bias (according to Bland and Altman) of all 43 evaluated systems ranged from -14.1% to +12.4%.

CONCLUSIONS

From the 34 systems completely assessed, 7 systems did not fulfill the minimal accuracy requirements of the ISO standard. The CE mark apparently does not guarantee that all BG systems provide accuracy according to the standard. Because inaccurate systems bear the risk of false therapeutic decisions, regular and standardized evaluation of BG meters and test strips should be requested in order to ensure adherence to quality standards.