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

Edible and medicinal mushrooms (Pleurotus ostreatus, Ustilago maydis, Ganoderma lucidum) reduce endoplasmic reticulum stress and inflammation in adipose tissue of obese Wistar rats fed with a high fat plus saccharose diet

Obesity is an increasing global public health problem. A strategy to treat obesity is the use of functional foods. Edible and medicinal mushrooms contain diverse bioactive compounds showing important antihyperlipidemic, antioxidant, and prebiotic properties. We analysed the effects of adding (10%) of Pleurotus ostreatus (Po, basidiomata), Ganoderma lucidum (Gl, basidiomata), or Ustilago maydis (Um, galls), milled, to a high fat plus saccharose diet (HFD + S) for 6 months in a model of obesity with Wistar rats. We assessed weight gain, body composition, lipid parameters, endoplasmic reticulum stress (proteins and inflammatory markers: BiP, XBP-1, JNK, p-JNK, TNF-α), and adiponectin in subcutaneous adipose tissue (SAT). The consumption of edible and medicinal mushrooms decreased weight gain (-17.2-30.1%) and fat mass (-23.7-43.1%), maintained fat-free mass, reduced levels of serum biochemical parameters (TC: -40.1-44.1%, TG: -37.7-51.6%, LDL-C: -64.5-71.1%), and prevented adipocyte hypertrophy (-30.9-36.9%) and collagen deposition (-70.9-73.7%) in SAT. Compared with the HFD + S group, mushroom consumption by Wistar rats significantly reduced the expression of proteins associated with endoplasmic reticulum stress and inflammation (BiP: -72.2-88.2%; XBP-1: -71.5-81.8%; JNK: -71.2-90.0%; p-JNK: -37.3-81.0%; TNF-α: -80.7-91.5%), whereas significantly increased adiponectin protein expression (246.4-654.2%) in SAT. These effects outperformed those obtained through the commercial lipid-lowering drug atorvastatin, contributing synergistically to prevent further obesity-related dysfunctions, such as insulin resistance derived from inflammation and ER stress in adipose tissue. Bioactive compounds from edible, functional and medicinal mushrooms represent new emerging therapies for obesity treatments using natural products.

Clinical Accuracy of a Glucose Oxidase-Based Blood Glucose Test-Strip Across Extremes of Oxygen Partial Pressure

BACKGROUND

Glucose oxidase (GOx)-based blood glucose monitors (BGMs) are influenced by the partial pressure of oxygen (Po2) within the applied sample. Limited in-clinic data exists regarding the quantitative effect of Po2 in unmanipulated capillary fingertip blood samples across physiologically representative glucose and Po2 ranges.

METHOD

Clinical accuracy data were collected as part of a BGM manufacturer's ongoing post-market surveillance program for a commercially available GOx-based BGM test-strip. The data set comprised 29 901 paired BGM-comparator readings and corresponding Po2 values from 5 428 blood samples from a panel of 975 subjects.

RESULTS

A linear regression-calculated bias range of 5.22% (+0.72% [low Po2: 45 mm Hg] to -4.5% [high Po2: 105 mm Hg]); biases calculated as absolute at <100 mg/dL glucose was found. Below the nominal Po2 of 75 mm Hg, a linear regression bias of +3.14% was calculated at low Po2, while negligible impact on bias (regression slope: +0.002%) was observed at higher than nominal levels (>75 mm Hg). When evaluating BGM performance under corner conditions of low (<70 mg/dL) and high (>180 mg/dL) glucose, combined with low and high Po2, linear regression biases ranged from +1.52% to -5.32% within this small group of subjects and with no readings recorded at <70 mg/dL glucose at low and high Po2.

CONCLUSIONS

Data from this large-scale clinical study, performed on unmanipulated fingertip capillary bloods from a diverse diabetes population, indicate Po2 sensitivity of the BGM to be markedly lower than published studies, which are mainly laboratory-based, requiring artificial manipulation of oxygen levels in aliquots of venous blood.

Mean Absolute Relative Difference of Blood Glucose Monitoring Systems and Relationship to ISO 15197

BACKGROUND

The analytical quality of a blood glucose monitoring system (BGMS) is often assessed according to the requirements described in the international standard ISO 15197. However, the mean absolute relative difference (MARD) is sometimes used as well. This analysis aims at providing empirical data from BGMS evaluation studies conducted according to ISO 15197 and at providing an estimation of how MARD and percentage of measurement results within ISO accuracy limits are related.

METHODS

Results of 77 system accuracy evaluations conducted according to ISO 15197 were used to calculate MARD between BGMS and a laboratory comparison method's results (glucose oxidase or hexokinase method). Additionally, bias and 95%-limits of agreement (LoA) using the Bland and Altman method were calculated.

RESULTS

MARD results ranged from 2.3% to 20.5%. The lowest MARD of a test strip lot that showed <95% of results within ISO limits was 6.1%. The distribution of MARD results shows that only 3.6% of test strip lots with a MARD equal to or below 7% showed <95% of results within ISO limits (2.2% of all test strip lots). Bias of test strip lots that showed ≥95% of results within the limits ranged from -10.3% to +7.4%. The half-width of the 95%-LoA of test strip lots that showed ≥95% of results within the limits ranged from 4.8% to 24.0%.

CONCLUSION

There is a threshold MARD that may allow an estimate whether ISO 15197 requirements are fulfilled, but this statement cannot be made with certainty.

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.

Mexican Ganoderma Lucidum Extracts Decrease Lipogenesis Modulating Transcriptional Metabolic Networks and Gut Microbiota in C57BL/6 Mice Fed with a High-Cholesterol Diet

Prevention of hyperlipidemia and associated diseases is a health priority. Natural products, such as the medicinal mushroom Ganoderma lucidum (Gl), have demonstrated hypocholesterolemic, prebiotic and antidiabetic properties. However, the underlying transcriptomic mechanisms by which Gl exerts bioactivities are not completely understood. We report a comprehensive hepatic and renal transcriptome profiling of C57BL/6 mice under the consumption of a high-cholesterol diet and two standardized Gl extracts obtained from basidiocarps cultivated on conventional substrate (Gl-1) or substrate containing acetylsalicylic acid (ASA; Gl-2). We showed that Gl extracts modulate relevant metabolic pathways involving the restriction of lipid biosynthesis and the enrichment of lipid degradation and secretion. The Gl-2 extract exerts a major modulation over gene expression programs showing the highest similarity with simvastatin druggable-target-genes and these are enriched more in processes related to human obesity alterations in the liver. We further show a subset of Gl-modulated genes correlated with Lactobacillus enrichment and the reduction of circulating cholesterol-derived fats. Moreover, Gl extracts induce a significant decrease of macrophage lipid storage, which occurs concomitantly with the down-modulation of Fasn and Elovl6. Collectively, this evidence suggests a new link between Gl hypocholesterolemic and prebiotic activity, revealing thereby that standardized Mexican Gl extracts are a novel transcriptome modulator to prevent metabolic disorders associated with hypercholesterolemia.

Getting More Information From Glucose Meter Evaluations

Glucose meter evaluations are common in publications and inform whether the meter meets the ISO 15197 specification. The ISO 15197 specifications, which are universally cited, leave 1% of results unspecified, which can be thought of as typical performance of results (99%) versus rare performance (1%). Suggestions are provided to extract more information from these evaluations, including rare performance, since highly discrepant results or failure to obtain a result can be observed in a glucose meter that has met the ISO 15197 specification. It is also recommended that when manufacturers perform evaluations, they analyze adverse events contained in the FDA MAUDE database. Finally, we point out an important problem with the ISO 15197 specifications.

The impact of provision of self-monitoring of blood glucose supplies on self-care activities among patients with uncontrolled Type 2 diabetes mellitus: A prospective study

AIMS

Self-monitoring of blood glucose (SMBG) is an important self-care activity for patients with Type 2 diabetes mellitus (T2DM) to achieve glycaemic control. The aim of this study was to evaluate the impact of providing SMBG supplies on self-care among patients with uncontrolled T2DM.

METHODS

This was a six-month, prospective study conducted in two primary care institutions. Patients ≥21 years old with uncontrolled T2DM (HbA1c > 7.0%) and polypharmacy (≥5 chronic medications) were included. All participants were given a free blood glucometer, test strips, and lancets, and were invited to consult pharmacists to learn about SMBG. The Summary of Diabetes Self-Care Activities questionnaire was administered at baseline and at six months.

RESULTS

A total of 167 patients were recruited and 150 (89.8%) completed the study. At six months, significant improvements from baseline were observed for overall self-care (+0.58, p = 0.008), glycemic control (-0.41%, p < 0.001) and all specific self-care activities. The mean change in the SMBG score in all the participants was found to have a strong positive correlation with the mean change in the overall self-care score (r_s = 0.580, p = 0.01).

CONCLUSIONS

Provision of SMBG supplies was effective in improving self-care among patients with uncontrolled T2DM, including non-insulin-treated patients.

Real-world practice level data analysis confirms link between variability within Blood Glucose Monitoring Strip (BGMS) and glycosylated haemoglobin (HbA1c) in Type 1 Diabetes

AIMS/HYPOTHESIS

Our aim was to quantify the impact of Blood Glucose Monitoring Strips variability (BGMSV) at GP practice level on the variability of reported glycated haemoglobin (HbA1cV) levels.

METHODS

Overall GP Practice BGMSV and HbA1cV were calculated from the quantity of main types of BGMS being prescribed combined with the published accuracy, as % results within ±% bands from reference value for the selected strip type. The regression coefficient between the BGMSV and HbA1cV was calculated. To allow for the aggregation of estimated three tests/day over 13 weeks (ie, 300 samples) of actual Blood Glucose (BG) values up to the HbA1c, we multiplied HbA1cV coefficient by √300 to estimate an empirical value for impact of BGMSV on BGV.

RESULTS

Four thousand five hundred and twenty-four practice years with 159 700 T1DM patient years where accuracy data were available for more than 80% of strips prescribed were included, with overall BGMSV 6.5% and HbA1c mean of 66.9 mmol/mol (8.3%) with variability of 13 mmol/mol equal to 19% of the mean. At a GP practice level, BGMSV and HbA1cV as % of mean HbA1c (in other words, the spread of HbA1c) were closely related with a regression coefficient of 0.176, P < 0.001. Thus, greater variability in the BGMS at a GP practice level resulted in a greater spread of HbA1C readings in T1DM patients. Applying this factor for BGMS to the national ISO accepted standard where 95% results must be ≤±15% from reference, revealed that for BG, 95% results would be ≤±45% from the reference value. Thus, the variation in BG is three times that of the BGMS. For a patient with BG target @10 mmol/L using the worst performing ISO standard strips, on 1/20 occasions (average 1/week) actual blood glucose value could be >±4.5 mmol/L from target, compared with the best performing BGMS with BG >±2.2 mmol/L from reference on 1/20 occasions.

CONCLUSION

Use of more variable/less accurate BGMS is associated both theoretically and in practice with a larger variability in measured BG and HbA1c, with implications for patient confidence in their day-to-day monitoring experience.

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.

Screening for dysglycaemia in dental primary care practice settings: systematic review of the evidence

INTRODUCTION

Increasing prevalence of diabetes and periodontal disease is prompting identification of additional clinical settings to identify patients at risk for dysglycaemia. A systematic review of studies that have examined feasibility of screening for at-risk patients in general dentistry settings at point-of-care (POC) was undertaken.

MATERIALS AND METHODS

Systematic review of pragmatic clinical field trials piloting POC screening for dysglycaemia risk in dental settings was undertaken in studies whose primary objective was to explore rates of dysglycaemia among undiagnosed patient populations.

RESULTS

Among 17 dental clinical field trials identified, 10 were systematically reviewed. High rates of undiagnosed dysglycaemia were detected among dental patients by biological screening in all trials. Notably, substantive differences in study design and population characteristics were identified, precluding meta-analysis.

CONCLUSION

Screening for dysglycaemia in dental offices effectively identified high-risk patients requiring triage for glycaemic management. Considerations for future clinical trial design were advanced to establish an evidence base amenable to meta-analysis of the relative translational value of glycaemic screening in dental settings.

Noninvasive Monitoring of Blood Glucose Using Color-Coded Photoplethysmographic Images of the Illuminated Fingertip Within the Visible and Near-Infrared Range: Opportunities and Questions

Noninvasive blood glucose assays have been promised for many years and various molecular spectroscopy-based methods of skin are candidates for achieving this goal. Due to the small spectral signatures of the glucose used for direct physical detection, moreover hidden among a largely variable background, broad spectral intervals are usually required to provide the mandatory analytical selectivity, but no such device has so far reached the accuracy that is required for self-monitoring of blood glucose (SMBG). A recently presented device as described in this journal, based on photoplethysmographic fingertip images for measuring glucose in a nonspecific indirect manner, is especially evaluated for providing reliable blood glucose concentration predictions.

Differences Between Flash Glucose Monitor and Fingerprick Measurements

Freestyle Libre (FL) is a factory calibrated Flash Glucose Monitor (FGM). We investigated Mean Absolute Relative Difference (MARD) between Self Monitoring of Blood Glucose (SMBG) and FL measurements in the first day of sensor wear in 39 subjects with Type 1 diabetes. The overall MARD was 12.3%, while the individual MARDs ranged from 4% to 25%. Five participants had a MARD ≥ 20%. We estimated bias and lag between the FL and SMBG measurements. The estimated biases range from -1.8 mmol / L to 1.4 mmol / L , and lags range from 2 min to 24 min . Bias is identified as a main cause of poor individual MARDs. The biases seem to persist in days 2⁻7 of sensor usage. All cases of MARD ≥ 20% in the first day are eliminated by bias correction, and overall MARD is reduced from 12.3% to 9.2%, indicating that adding support for voluntary user-supplied bias correction in the FL could improve its performance.

Traceability to a primary reference measurement procedure (ID-LCMS); A key step in validating the clinical accuracy and safety of hospital blood glucose monitoring systems

OBJECTIVE

A key step in the evaluation of the accuracy of blood glucose monitoring systems (BGMS) is using a comparator method aligned to a high order definitive reference method. We describe how we achieved traceability to an isotope dilution liquid chromatography mass spectrometry (ID-LCMS) method. We used ID-LCMS to evaluate the accuracy and specificity of two hospital BGMS used in China.

METHOD

ID-LCMS was used to verify the calibration alignment of the laboratory plasma hexokinase reference method using NIST standard reference material and clinical samples. The ID-LCMS aligned hexokinase method was used to evaluate the clinical accuracy of two BGMS in hospitalized patients. System accuracy was evaluated using Chinese consensus guidelines. BGMS accuracy was also assessed with interference factors known to be present in critically ill patients' blood.

RESULTS

The laboratory plasma hexokinase reference method was shown to calibrate closely with ID-LCMS. Two BGMS demonstrated good correlation with this reference method. Only one BGMS met the Chinese guidelines. The interference factors didn't influence this BGMS but adversely affected the clinical accuracy of the other.

CONCLUSIONS

We advocate that our IDMS calibration alignment approach for ensuring the accuracy of the glucose reference method should be adopted in evaluations assessing the accuracy of blood glucose monitoring systems.

Strengths and Limitations of New Approaches for Graphical Presentation of Blood Glucose Monitoring System Accuracy Data

Graphical presentation of blood glucose monitoring systems' (BGMSs) accuracy typically includes difference plots (DPs). Recently, 3 new approaches were presented: radar plots (RPs), rectangle target plots (RTPs), and surveillance error grids (SEGs). BGMS data were modeled based on 3 scenarios that can be encountered in real life to highlight strengths and limitations of these approaches. Detailed assessment of BGMS data may be easier in plots with individual data points (DPs, RPs, SEGs), whereas RTPs may facilitate display of large amounts of data or comparison of BGMS. SEGs have the advantage of assessing clinical risk. The selection of a specific type depends mostly on the kind of information sought (eg, accuracy in specific concentration intervals, lot-to-lot variability, clinical risk) as there is no "absolute best" approach.

Accuracy Evaluation of 19 Blood Glucose Monitoring Systems Manufactured in the Asia-Pacific Region: A Multicenter Study

BACKGROUND

System accuracy of current blood glucose monitors (BGMs) in the market has already been evaluated extensively, yet mostly focused on European and North American manufacturers. Data on BGMs manufactured in the Asia-Pacific region remain to be established. In this study, we sought to assess the accuracy performance of 19 BGMs manufactured in the Asia-pacific region.

METHODS

A total of 19 BGMs were obtained from local pharmacies in China. The study was conducted at three hospitals located in the Asia-Pacific region. Measurement results of each system were compared with results of the reference instrument (YSI 2300 PLUS Glucose Analyzer), and accuracy evaluation was performed in accordance to the ISO 15197:2003 and updated 2015 guidelines. Radar plots, which is a new method, are described herein to visualize the analytical performance of the 19 BGMs evaluated. Consensus error grid is a tool for evaluating the clinical significance of the results.

RESULTS

The 19 BGMs resulted in a satisfaction rate between 83.5% and 100.0% within ISO 15197:2003 error limits, and between 71.3% and 100.0% within EN ISO 15197:2015 (ISO 15197:2013) error limits.

CONCLUSIONS

Of the 19 BGMs evaluated, 12 met the minimal accuracy requirement of the ISO 15197:2003 standard, whereas only 4 met the tighter EN ISO 15197:2015 (ISO 15197:2013) requirements. Accuracy evaluation of BGMs should be performed regularly to maximize patient safety.

Demonstration of disinfection procedure for the development of accurate blood glucose meters in accordance with ISO 15197:2013

Despite measures to reduce disease transmission, a risk can occur when blood glucose meters (BGMs) are used on multiple individuals or by caregivers assisting a patient. The laboratory and in-clinic performance of a BGM system before and after disinfection should be demonstrated to guarantee accurate readings and reliable control of blood glucose (BG) for patients. In this study, an effective disinfection procedure, conducting wiping 10 times to assure a one minute contact time of the disinfectant on contaminated surface, was first demonstrated using test samples of the meter housing materials, including acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), and polycarbonate (PC), in accordance with ISO 15197:2013. After bench studies comprising 10,000 disinfection cycles, the elemental compositions of the disinfected ABS, PMMA, and PC samples were almost the same as in the original samples, as indicated by electron spectroscopy for chemical analysis. Subsequently, the validated disinfection procedure was then directly applied to disinfect 5 commercial BGM systems composed of ABS, PMMA, or PC to observe the effect of the validated disinfection procedure on meter accuracy. The results of HBsAg values after treatment with HBV sera and disinfectant wipes for each material were less than the LoD of each material of 0.020 IU/mL. Before and after the multiple disinfection cycles, 900 of 900 samples (100%) were within the system accuracy requirements of ISO 15197:2013. All of the systems showed high performance before and after the series of disinfection cycles and met the ISO 15197:2013 requirements. In addition, our results demonstrated multiple cleaning and disinfection cycles that represented normal use over the lifetime of a meter of 3-5 years. Our validated cleaning and disinfection procedure can be directly applied to other registered disinfectants for cleaning commercial BGM products in the future.

A Model of Self-Monitoring Blood Glucose Measurement Error

BACKGROUND

A reliable model of the probability density function (PDF) of self-monitoring of blood glucose (SMBG) measurement error would be important for several applications in diabetes, like testing in silico insulin therapies. In the literature, the PDF of SMBG error is usually described by a Gaussian function, whose symmetry and simplicity are unable to properly describe the variability of experimental data. Here, we propose a new methodology to derive more realistic models of SMBG error PDF.

METHODS

The blood glucose range is divided into zones where error (absolute or relative) presents a constant standard deviation (SD). In each zone, a suitable PDF model is fitted by maximum-likelihood to experimental data. Model validation is performed by goodness-of-fit tests. The method is tested on two databases collected by the One Touch Ultra 2 (OTU2; Lifescan Inc, Milpitas, CA) and the Bayer Contour Next USB (BCN; Bayer HealthCare LLC, Diabetes Care, Whippany, NJ). In both cases, skew-normal and exponential models are used to describe the distribution of errors and outliers, respectively.

RESULTS

Two zones were identified: zone 1 with constant SD absolute error; zone 2 with constant SD relative error. Goodness-of-fit tests confirmed that identified PDF models are valid and superior to Gaussian models used so far in the literature.

CONCLUSIONS

The proposed methodology allows to derive realistic models of SMBG error PDF. These models can be used in several investigations of present interest in the scientific community, for example, to perform in silico clinical trials to compare SMBG-based with nonadjunctive CGM-based insulin treatments.

How Can We Realize the Clinical Benefits of Continuous Glucose Monitoring?

Controlling glycemia in diabetes remains key to prevent complications in this condition. However, glucose levels can undergo large fluctuations secondary to daily activities, consequently creating management difficulties. The current review summarizes the basics of glucose management in diabetes by addressing the main glycemic parameters. The advantages and limitation of HbA1c, the gold standard measure of glucose control, are discussed together with the clinical importance of hypoglycemia and glycemic variability. The review subsequently moves focus to glucose monitoring techniques in diabetes, assessing advantages and limitations. Monitoring glucose levels is crucial for effective and safe adjustment of hypoglycemic therapy, particularly in insulin users. Self-monitoring of blood glucose (SMBG), based on capillary glucose testing, remains one of the most widely used methods to monitor glucose levels, given the relative accuracy, familiarity, and manageable costs. However, patient inconvenience and the sporadic nature of SMBG limit clinical effectiveness of this approach. In contrast, continuous glucose monitoring (CGM) provides a more comprehensive picture of glucose levels, but these systems are expensive and require constant calibration which, together with concerns over accuracy of earlier devices, restrict CGM use to special groups of patients. The newer flash continuous glucose monitoring (FCGM) system, which is more affordable than conventional CGM devices and does not require calibration, offers an alternative glucose monitoring strategy that comprehensively analyzes glucose profile while sparing patients the inconvenience of capillary glucose testing for therapy adjustment or CGM calibration. The fast development of new CGM devices will gradually displace SMBG as the main glucose testing method. Avoiding the inconvenience of SMBG and optimizing glycemia through alternative glucose testing strategies will help to reduce the risk of complications and improve quality of life in patients with diabetes.

Comparative Accuracy of 17 Point-of-Care Glucose Meters

BACKGROUND

The accuracy of point-of-care blood glucose (BG) meters is important for the detection of dysglycemia, calculation of insulin doses, and the calibration of continuous glucose monitors. The objective of this study was to compare the accuracy of commercially available glucose meters in a challenging laboratory study using samples with a wide range of reference BG and hemoglobin values.

METHODS

Fresh, discarded blood samples from a hospital STAT laboratory were either used without modification, spiked with a glucose solution, or incubated at 37°C to produce 347 samples with an even distribution across reference BG levels from 20 to 440 mg/dl and hemoglobin values from 9 to 16 g/dl. We measured the BG of each sample with 17 different commercially available glucose meters and the reference method (YSI 2300) at the same time. We determined the mean absolute relative difference (MARD) for each glucose meter, overall and stratified by reference BG and by hemoglobin level.

RESULTS

The accuracy of different meters widely, exhibiting a range of MARDs from 5.6% to 20.8%. Accuracy was lower in the hypoglycemic range, but was not consistently lower in samples with anemic blood hemoglobin levels.

CONCLUSIONS

The accuracy of commercially available glucose meters varies widely. Although the sample mix in this study was much more challenging than those that would be collected under most use conditions, some meters were robust to these challenges and exhibited high accuracy in this setting. These data on relative accuracy and robustness to challenging samples may be useful in informing the choice of a glucose meter.

Barriers to Patient Use of Control Solution for Glucose Meters: Surveys of Patients, Pharmacists, and Providers in a Metropolitan Area

BACKGROUND

An important factor in controlling diabetes is self-monitoring of blood glucose. Manufacturers of glucose meters recommend routine use of control solution to ensure accuracy. Previous studies have demonstrated that glucose meters vary in accuracy and that patients are not using control solution as recommended. The purpose of this study is to identify potential barriers to control solution use from multiple perspectives including patient, pharmacist, and provider.

METHODS

This study was a prospective, observational survey design. First, 25 randomly selected chain and independent pharmacies in the Tulsa metropolitan area were audited for control solution accessibility. These pharmacies were then used to survey pharmacists, via telephone, regarding control solution inventory and perception of importance of use. Next, providers were electronically surveyed on their routine practice recommendations, while 60 patients with diabetes were randomly selected for telephone survey on use and perceptions of control solution.

RESULTS

Twenty-five pharmacies were audited and 23 pharmacists, 60 patients, and 29 providers were surveyed. Only 39% of pharmacies stated they supplied control solution, however, only 1 pharmacy visibly stocked it. The only patient factor that appeared to have an impact on control solution usage was having type 1 versus type 2 diabetes (38% vs 15%). Providers are aware of what control solution is (62%), but only half felt it should be routine practice with 44% of those never recommending it.

CONCLUSION

This study raises awareness for the need to educate patients, providers, and pharmacists about use of control solution to ensure glucose meter accuracy.

Accuracy Evaluation of Four Blood Glucose Monitoring Systems in the Hands of Intended Users and Trained Personnel Based on ISO 15197 Requirements

BACKGROUND

Self-monitoring of blood glucose (BG) is an integral part in the therapy of people with diabetes, which is why blood glucose monitoring systems (BGMS) have to fulfill minimum accuracy requirements. However, accuracy is often assessed by trained operators, although such assessments do not necessarily allow for drawing conclusions on accuracy in the hands of lay users.

METHODS

The accuracy of 4 different BGMS (Accu-Chek^® Active, Accu-Chek^® Performa, Contour^®Plus, and OneTouch^® SelectSimple™) in the hands of lay users and trained study personnel was assessed in this study. Procedures were based on International Organization for Standardization (ISO) 15197:2013, clause 8, requirements. BGMS measurement results were compared against results from a glucose oxidase and a hexokinase laboratory analyzer. Handling errors made by lay users were documented. Accuracy was evaluated applying ISO 15197:2013/EN ISO 15197:2015 criteria (percentage of results within ±15 mg/dL or ±15%), more stringent criteria (10 mg/dL or 10%, and 5 mg/dL or 5%, respectively), and ISO 15197:2003 system accuracy criteria.

RESULTS

The level of accuracy differed among the four BGMS investigated independent from the operator. One system had less than 95% of the values within each of the limits and one system showed marked differences in accuracy when used by trained personnel and by lay users. Common lay user errors were not checking the test strip codes, incorrect application of blood, and not using the blood drop immediately.

CONCLUSIONS

BGMS accuracy can differ when used by trained personnel and when used by lay users. It is important that BGMS manufacturers provide systems that are as insensitive to operator errors as technically possible and easy to use.

Boluses in Insulin Therapy

Giving a bolus is one major part in multiple dose insulin therapy (MDI) along with basal insulin substitution. To adjust the bolus optimally, different factors like carbohydrate content and composition of the meal, correction factors, and timing have to be considered. Advances in technologies like bolus advisors can assist the patients but still there a several open questions and technical challenges regarding boluses. This commentary provides an opportunity to address several of the above-mentioned factors influencing the result of bolusing. It shall draw attention to those factors and address the current opportunities, for example, continuous subcutaneous insulin infusion (CSII), as well as the need for further studies which can help to improve diabetes insulin therapy by means of the correct use of boluses.

Clinical review: the misreporting of logbook, download, and verbal self-measured blood glucose in adults and children with type I diabetes

Despite advances in technology, the frequent self-measurement of blood glucose (SMBG) remains fundamental to the management of 1 diabetes mellitus (T1DM). Once measured, SMBG results are routinely reported back to health professionals and other interested parties, either verbally, via a logbook, or electronically downloaded from a pump or meter. The misreporting of SMBG using various techniques represents a classic non-adherence behavior and carries with it both acute and chronic dangers. In addition, while this behavior appears very prevalent, many aspects remain largely unstudied. With this in mind, we aimed to summarize literature addressing the misreporting of SMBG in T1DM via a detailed literature search. This produced both recent and past literature. While most of these studies examined the prevalence of deliberate misreporting in a verbal or logbook context, others focused on the motivations behind this behavior, and alternative forms of misreporting, including deliberate manipulation of meters to produce inaccurate results and true technological errors. This timely review covers all aspects of misreporting and highlights multiple patient techniques, which are clearly adapting to advances in technology. We believe that further understanding and attention to this aspect of adherence may lead not only to improvements in glycemic control and safety, but also to the psychological well-being of those affected by type 1 diabetes.

Large-scale performance evaluation of Accu-Chek inform II point-of-care glucose meters

BACKGROUND

The aim of this study was to report the experience of large-scale performance evaluation of 238 Accu-Chek Inform II point-of-care (POC) glucose meters in a single medical setting.

METHODS

The repeatability of 238 POC devices, the within-site imprecision of 12 devices, and the linearity of 49 devices were evaluated using glucose control solutions. The glucose results of 24 POC devices and central laboratory were compared using patient samples.

RESULTS

Mean concentration of control solutions was 2.39 mmol/L for Level 1 and 16.52 mmol/L for Level 2. The pooled repeatability coefficient of variation (CV) of the 238 devices was 2.0% for Level 1 and 1.6% for Level 2. The pooled within-site imprecision CV and reproducibility CV of the 12 devices were 2.7% and 2.7% for Level 1, and 1.9%, and 1.9% for Level 2, respectively. The test results of all 49 devices were linear within analytical measurement range from 1.55-31.02 mmol/L. The correlation coefficient for individual POC devices ranged from 0.9967-0.9985. The total correlation coefficient for the 24 devices was 0.998.

CONCLUSIONS

The Accu-Chek Inform II POC blood glucose meters performed well in terms of precision, linearity, and correlation evaluations. Consensus guidelines for the large-scale performance evaluations of POC devices are required.

Novel fungal FAD glucose dehydrogenase derived from Aspergillus niger for glucose enzyme sensor strips

In this study, a novel fungus FAD dependent glucose dehydrogenase, derived from Aspergillus niger (AnGDH), was characterized. This enzyme's potential for the use as the enzyme for blood glucose monitor enzyme sensor strips was evaluated, especially by investigating the effect of the presence of xylose during glucose measurements. The substrate specificity of AnGDH towards glucose was investigated, and only xylose was found as a competing substrate. The specific catalytic efficiency for xylose compared to glucose was 1.8%. The specific activity of AnGDH for xylose at 5mM concentration compared to glucose was 3.5%. No other sugars were used as substrate by this enzyme. The superior substrate specificity of AnGDH was also demonstrated in the performance of enzyme sensor strips. The impact of spiking xylose in a sample with physiological glucose concentrations on the sensor signals was investigated, and it was found that enzyme sensor strips using AnGDH were not affected at all by 5mM (75mg/dL) xylose. This is the first report of an enzyme sensor strip using a fungus derived FADGDH, which did not show any positive bias at a therapeutic level xylose concentration on the signal for a glucose sample. This clearly indicates the superiority of AnGDH over other conventionally used fungi derived FADGDHs in the application for SMBG sensor strips. The negligible activity of AnGDH towards xylose was also explained on the basis of a 3D structural model, which was compared to the 3D structures of A. flavus derived FADGDH and of two glucose oxidases.

Hypocholesterolemic Properties and Prebiotic Effects of Mexican Ganoderma lucidum in C57BL/6 Mice

Edible and medicinal mushrooms contain bioactive compounds with promising effects on several cardiovascular risk biomarkers. However, strains of Ganoderma lucidum of Mexican origin have not yet been studied. Standardized extracts of G. lucidum (Gl) were given to C57BL/6 mice fed a high-cholesterol diet compared with the drug simvastatin. The effects of the extracts on serum biochemical parameters, liver lipid content, cholesterol metabolism, and the composition of gut microbiota were assessed. Acetylsalicylic acid (10 mM) added to the cultivation substrate modulated properties of Gl extracts obtained from mature basidiomata. Compared to the high-cholesterol diet group, the consumption of Gl extracts significantly reduced total serum cholesterol (by 19.2% to 27.1%), LDL-C (by 4.5% to 35.1%), triglyceride concentration (by 16.3% to 46.6%), hepatic cholesterol (by 28.7% to 52%) and hepatic triglycerides (by 43.8% to 56.6%). These effects were associated with a significant reduction in the expression of lipogenic genes (Hmgcr, Srebp1c, Fasn, and Acaca) and genes involved in reverse cholesterol transport (Abcg5 and Abcg8), as well as an increase in Ldlr gene expression in the liver. No significant changes were observed in the gene expression of Srebp2, Abca1 or Cyp7a1. In several cases, Gl-1 or Gl-2 extracts showed better effects on lipid metabolism than the drug simvastatin. A proposed mechanism of action for the reduction in cholesterol levels is mediated by α-glucans and β-glucans from Gl, which promoted decreased absorption of cholesterol in the gut, as well as greater excretion of fecal bile acids and cholesterol. The prebiotic effects of Gl-1 and Gl-2 extracts modulated the composition of gut microbiota and produced an increase in the Lactobacillaceae family and Lactobacillus genus level compared to the control group, high-cholesterol diet group and group supplemented with simvastatin. Mexican genetic resources of Gl represent a new source of bioactive compounds showing hypocholesterolemic properties and prebiotic effects.

Performance of a Blood Glucose Monitoring System in a Point-of-Care Setting

This study assesses and demonstrates that CONTOUR® XT-BGMS (CXT-BGMS) complies with the requirements of the German (RiliBÄK) and Swiss (QUALAB) quality control guidelines for point-of-care testing (POCT) and fulfills the ISO15197:2013 accuracy limits criteria under the routine conditions of a hospital point-of care setting. This single-center study was conducted in Switzerland using 105 venous blood samples from hospitalized patients. Each sample was tested in comparison to the hexokinase reference method. Compliance with POCT guidelines was assessed by daily BGMS measurements using control solutions. Accuracy of CXT-BGMS according to ISO limits was 98.41%. All control measurements were within the limits defined by RiliBÄK (within ± 11% of target values and root mean square error [RMSE] within RMSE limits), and QUALAB (within ± 10% of target values).

Requirements for Successful Adoption of a Glucose Measurement System Into a Hospital POC Program

Widespread and successful implementation of any glucose measurement system in a hospital point-of-care (POC) program requires a number of features in addition to accurate and reliable analytical performance. Such features include, but are not limited to, a system's glucose-hematocrit dependence, durability, information technology capabilities, and battery capacity and battery life. While the study of Ottiger et al in this issue supports the analytical accuracy and reliability of Bayer's CONTOUR XT® blood glucose monitoring system, the suitability of other features of this system for a hospital POC program remains to be established.

Feasibility of an Orthogonal Redundant Sensor incorporating Optical plus Redundant Electrochemical Glucose Sensing

BACKGROUND

Orthogonal redundancy for glucose sensing (multiple sensing elements utilizing distinct methodologies) may enhance performance compared to nonredundant sensors, and to sensors with multiple elements utilizing the same technology (simple redundancy). We compared the performance of a prototype orthogonal redundant sensor (ORS) combining optical fluorescence and redundant electrochemical sensing via a single insertion platform to an electrochemical simple redundant sensor (SRS).

METHODS

Twenty-one adults with type 1 diabetes wore an ORS and an SRS concurrently for 7 days. Following sensor insertion, and on Day 4 with a standardized meal, frequent venous samples were collected for reference glucose measurement (laboratory [YSI] and meter) over 3 and 4 hours, respectively. Between study visits reference capillary blood glucose testing was undertaken. Sensor data were processed prospectively.

RESULTS

ORS mean absolute relative difference (MARD) was (mean ± SD) 10.5 ± 13.2% versus SRS 11.0 ± 10.4% (P = .34). ORS values in Clarke error grid zones A and A+B were 88.1% and 97.6%, respectively, versus SRS 86.4% and 97.8%, respectively (P = .23 and P = .84). ORS Day 1 MARD (10.7 ± 10.7%) was superior to SRS (16.5 ± 13.4%; P < .0001), and comparable to ORS MARD for the week. ORS sensor survival (time-averaged mean) was 92.1% versus SRS 74.4% (P = .10). ORS display time (96.0 ± 5.8%) was equivalent to SRS (95.6 ± 8.9%; P = .87).

CONCLUSIONS

Combining simple and orthogonal sensor redundancy via a single insertion is feasible, with accuracy comparing favorably to current generation nonredundant sensors. Addition of an optical component potentially improves sensor reliability compared to electrochemical sensing alone. Further improvement in optical sensing performance is required prior to clinical application.

Redundancy in Glucose Sensing: Enhanced Accuracy and Reliability of an Electrochemical Redundant Sensor for Continuous Glucose Monitoring

BACKGROUND

Current electrochemical glucose sensors use a single electrode. Multiple electrodes (redundancy) may enhance sensor performance. We evaluated an electrochemical redundant sensor (ERS) incorporating two working electrodes (WE1 and WE2) onto a single subcutaneous insertion platform with a processing algorithm providing a single real-time continuous glucose measure.

METHODS

Twenty-three adults with type 1 diabetes each wore two ERSs concurrently for 168 hours. Post-insertion a frequent sampling test (FST) was performed with ERS benchmarked against a glucose meter (Bayer Contour Link). Day 4 and 7 FSTs were performed with a standard meal and venous blood collected for reference glucose measurements (YSI and meter). Between visits, ERS was worn with capillary blood glucose testing ≥8 times/day. Sensor glucose data were processed prospectively.

RESULTS

Mean absolute relative deviation (MARD) for ERS day 1-7 (3,297 paired points with glucose meter) was (mean [SD]) 10.1 [11.5]% versus 11.4 [11.9]% for WE1 and 12.0 [11.9]% for WE2; P < .0001. ERS Clarke A and A+B were 90.2% and 99.8%, respectively. ERS day 4 plus day 7 MARD (1,237 pairs with YSI) was 9.4 [9.5]% versus 9.6 [9.7]% for WE1 and 9.9 [9.7]% for WE2; P = ns. ERS day 1-7 precision absolute relative deviation (PARD) was 9.9 [3.6]% versus 11.5 [6.2]% for WE1 and 10.1 [4.4]% for WE2; P = ns. ERS sensor display time was 97.8 [6.0]% versus 91.0 [22.3]% for WE1 and 94.1 [14.3]% for WE2; P < .05.

CONCLUSIONS

Electrochemical redundancy enhances glucose sensor accuracy and display time compared with each individual sensing element alone. ERS performance compares favorably with 'best-in-class' of non-redundant sensors.

Promoting health and reducing costs: a role for reform of self-monitoring of blood glucose provision within the National Health Service

AIM

To determine the cost-effectiveness of all options for the self-monitoring of blood glucose funded by the National Health Service, providing guidance for disinvestment and testing the hypothesis that advanced meter features may justify higher prices.

METHODS

Using data from the Health and Social Care Information Centre concerning all 8 340 700 self-monitoring of blood glucose-related prescriptions during 2013/2014, we conducted a cost-minimization analysis, considering both strip and lancet costs, including all clinically equivalent technologies for self-monitoring of blood glucose, as determined by the ability to meet ISO-15197:2013 guidelines for meter accuracy.

RESULTS

A total of 56 glucose monitor, test strip and lancet combinations were identified, of which 38 met the required accuracy standards. Of these, the mean (range) net ingredient costs for test strips and lancets were £0.27 (£0.14-£0.32) and £0.04 (£0.02-£0.05), respectively, resulting in a weighted average of £0.28 (£0.18-£0.37) per test. Systems providing four or more advanced features were priced equal to those providing just one feature. A total of £12 m was invested in providing 42 million self-monitoring of blood glucose tests with systems that fail to meet acceptable accuracy standards, and efficiency savings of £23.2 m per annum are achievable if the National Health Service were to disinvest from technologies providing lesser functionality than available alternatives, but at a much higher price.

CONCLUSION

The study uncovered considerable variation in the price paid by the National Health Service for self-monitoring of blood glucose, which could not be explained by the availability of advanced meter features. A standardized approach to self-monitoring of blood glucose prescribing could achieve significant efficiency savings for the National Health Service, whilst increasing overall utilisation and improving safety for those currently using systems that fail to meet acceptable standards for measurement accuracy.

Evaluation of Blood Glucose Meter Efficacy in an Antenatal Diabetes Clinic

BACKGROUND

The optimal treatment of diabetes in pregnancy requires accurate measurement of blood glucose levels, in order to minimize adverse outcomes for both mother and neonate. Self-monitoring of blood glucose is routinely used to measure glycemic control and to assess whether treatment targets are being met; however, the accuracy of blood glucose meters in pregnancy is unclear.

MATERIALS AND METHODS

Pregnant women with gestational, type 1, or type 2 diabetes mellitus were eligible to participate. Nonfasting capillary blood glucose levels were measured in duplicate using the BGStar(®) (Sanofi, Sydney, Australia) and FreeStyle Lite(®) (Abbott, Sydney) blood glucose meters. Venous blood samples were collected and analyzed for plasma glucose, hematocrit, and glycated hemoglobin. Capillary blood glucose was compared with plasma glucose and further assessed according to International Organization for Standardization (ISO) 15197:2013 standards.

RESULTS

One hundred ten women were recruited, providing 96 samples suitable for analysis. The mean ± SD laboratory plasma glucose level was 4.6 ± 1.4 mmol/L; the BGStar and FreeStyle Lite capillary blood glucose values were 5.3 ± 1.4 mmol/L and 5.0 ± 1.3 mmol/L, respectively. Both meters showed a positive bias (0.42 mmol/L for the FreeStyle Lite and 0.65 mmol/L for the BGStar). Furthermore, neither meter fulfilled the ISO 15197:2013 standards, and there was a nonsignificant improvement in meter performance at blood glucose levels of ≤4.2 mmol/L. Hematocrit did not affect the results of either blood glucose meter. Clarke Error Grid analysis demonstrated that approximately 70% of the results of both meters would lead to appropriate clinical action.

CONCLUSIONS

The BGStar and FreeStyle Lite blood glucose meters did not meet ISO 15197:2013 recommendations for blood glucose monitoring systems when assessed in a population of women with diabetes in pregnancy. Clinicians should consider this difference in blood glucose readings when making diabetes-related treatment decisions.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY 2016 OUTPATIENT GLUCOSE MONITORING CONSENSUS STATEMENT

This document represents the official position of the American Association of Clinical Endocrinologists and American College of Endocrinology. Where there were no randomized controlled trials or specific U.S. FDA labeling for issues in clinical practice, the participating clinical experts utilized their judgment and experience. Every effort was made to achieve consensus among the committee members. Position statements are meant to provide guidance, but they are not to be considered prescriptive for any individual patient and cannot replace the judgment of a clinician.

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.

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

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.

System Accuracy Evaluation of Different Blood Glucose Monitoring Systems Following ISO 15197:2013 by Using Two Different Comparison Methods

BACKGROUND

Adherence to established standards (e.g., International Organization for Standardization [ISO] 15197) is important to ensure comparable and sufficient accuracy of systems for self-monitoring of blood glucose (SMBG). Accuracy evaluation was performed for different SMBG systems available in Europe with three reagent lots each.

MATERIALS AND METHODS

Test procedures followed the recently published revision ISO 15197:2013. Comparison measurements were performed with a glucose oxidase (YSI 2300 STAT Plus™ glucose analyzer; YSI Inc., Yellow Springs, OH) and a hexokinase (cobas Integra(®) 400 Plus analyzer; Roche Instrument Center, Rotkreuz, Switzerland) method. Compliance with ISO 15197:2013 accuracy criteria was determined by calculating the percentage of results within ±15% or within ±0.83 mmol/L of the comparison measurement results for glucose concentrations at and above or below 5.55 mmol/L, respectively, and by calculating the percentage of results within consensus error grid Zones A and B.

RESULTS

Seven systems showed with all three tested lots that 95-100% of the results were within the accuracy limits of ISO 15197:2013 and that 100% of results were within consensus error grid Zones A and B, irrespective of the comparison method used. Regarding results of individual lots, slight differences between the glucose oxidase method and the hexokinase method were found. Accuracy criteria of ISO 15197:2003 (±20% for concentrations ≥4.2 mmol/L and±0.83 mmol/L for concentrations <4.2 mmol/L) were fulfilled by eight systems with all three lots and by one system with two lots.

CONCLUSIONS

In this study, seven systems complied with the accuracy criteria of ISO 15197:2013. The results also indicate that the comparison measurement method/system is important, as it may have a considerable impact on accuracy data obtained for a system.

A Multicenter Performance Evaluation of a Blood Glucose Monitoring System in 21 Leading Hospitals in Spain

BACKGROUND

Self-monitoring of blood glucose is crucial for the effective self-management of diabetes. The present study evaluated the accuracy of the Contour® XT blood glucose monitoring system (BGMS) compared to the reference method in a large multicenter study under routine lab conditions at each hospital site.

METHODS

This study was conducted at 21 leading hospitals in Spain using leftover whole blood samples (n = 2100). Samples were tested with the BGMS using 1 commercial strip lot and the local laboratory hexokinase method. BGMS accuracy was assessed and results were compared to ISO 15197:2013 accuracy limit criteria and by using mean absolute relative difference analysis (MARD), consensus (Parkes) error grid (CEG), and surveillance error grid analyses (SEG).

RESULTS

Pooled analysis of 2100 measurements from all sites showed that 99.43% of the BGMS results were within the ranges accepted by the accuracy limit criteria. The overall MARD was 3.85%. MARD was 4.47% for glucose concentrations < 70 mg/dL and 3.81% for concentrations of 70-300 mg/dL. In CEG, most results (99.8%) were within zone A ("no effect on clinical action"); the remaining ones (0.2%) were in zone B ("little to no effect on clinical action"). The SEG analysis showed that most of the results (98.4%) were in the "no risk" zone, with the remaining results in the "slight, lower" risk zone.

CONCLUSIONS

This is the largest multicenter study of Contour XT BGMS to date, and shows that this BGMS meets the ISO 15197:2013 accuracy limit criteria under local routine conditions in 21 leading Spanish hospitals.

Analytical Performance Requirements for Systems for Self-Monitoring of Blood Glucose With Focus on System Accuracy: Relevant Differences Among ISO 15197:2003, ISO 15197:2013, and Current FDA Recommendations

In the European Union (EU), the ISO (International Organization for Standardization) 15197 standard is applicable for the evaluation of systems for self-monitoring of blood glucose (SMBG) before the market approval. In 2013, a revised version of this standard was published. Relevant revisions in the analytical performance requirements are the inclusion of the evaluation of influence quantities, for example, hematocrit, and some changes in the testing procedures for measurement precision and system accuracy evaluation, for example, number of test strip lots. Regarding system accuracy evaluation, the most important change is the inclusion of more stringent accuracy criteria. In 2014, the Food and Drug Administration (FDA) in the United States published their own guidance document for the premarket evaluation of SMBG systems with even more stringent system accuracy criteria than stipulated by ISO 15197:2013. The establishment of strict accuracy criteria applicable for the premarket evaluation is a possible approach to further improve the measurement quality of SMBG systems. However, the system accuracy testing procedure is quite complex, and some critical aspects, for example, systematic measurement difference between the reference measurement procedure and a higher-order procedure, may potentially limit the apparent accuracy of a given system. Therefore, the implementation of a harmonized reference measurement procedure for which traceability to standards of higher order is verified through an unbroken, documented chain of calibrations is desirable. In addition, the establishment of regular and standardized post-marketing evaluations of distributed test strip lots should be considered as an approach toward an improved measurement quality of available SMBG systems.

Performance of Cleared Blood Glucose Monitors

Cleared blood glucose monitor (BGM) systems do not always perform as accurately for users as they did to become cleared. We performed a literature review of recent publications between 2010 and 2014 that present data about the frequency of inaccurate performance using ISO 15197 2003 and ISO 15197 2013 as target standards. We performed an additional literature review of publications that present data about the clinical and economic risks of inaccurate BGMs for making treatment decisions or calibrating continuous glucose monitors (CGMs). We found 11 publications describing performance of 98 unique BGM systems. 53 of these 98 (54%) systems met ISO 15197 2003 and 31 of the 98 (32%) tested systems met ISO 15197 2013 analytical accuracy standards in all studies in which they were evaluated. Of the tested systems, 33 were identified by us as FDA-cleared. Among these FDA-cleared BGM systems, 24 out of 32 (75%) met ISO 15197 2003 and 15 out of 31 (48.3%) met ISO 15197 2013 in all studies in which they were evaluated. Among the non-FDA-cleared BGM systems, 29 of 65 (45%) met ISO 15197 2003 and 15 out of 65 (23%) met ISO 15197 2013 in all studies in which they were evaluated. It is more likely that an FDA-cleared BGM system, compared to a non-FDA-cleared BGM system, will perform according to ISO 15197 2003 (χ(2) = 6.2, df = 3, P = 0.04) and ISO 15197 2013 (χ(2) = 11.4, df = 3, P = 0.003). We identified 7 articles about clinical risks and 3 articles about economic risks of inaccurate BGMs. We conclude that a significant proportion of cleared BGMs do not perform at the level for which they were cleared or according to international standards of accuracy. Such poor performance leads to adverse clinical and economic consequences.

System Accuracy Evaluation of Four Systems for Self-Monitoring of Blood Glucose Following ISO 15197 Using a Glucose Oxidase and a Hexokinase-Based Comparison Method

BACKGROUND

The standard ISO (International Organization for Standardization) 15197 is widely accepted for the accuracy evaluation of systems for self-monitoring of blood glucose (SMBG). Accuracy evaluation was performed for 4 SMBG systems (Accu-Chek Aviva, ContourXT, GlucoCheck XL, GlucoMen LX PLUS) with 3 test strip lots each. To investigate a possible impact of the comparison method on system accuracy data, 2 different established methods were used.

METHODS

The evaluation was performed in a standardized manner following test procedures described in ISO 15197:2003 (section 7.3). System accuracy was assessed by applying ISO 15197:2003 and in addition ISO 15197:2013 criteria (section 6.3.3). For each system, comparison measurements were performed with a glucose oxidase (YSI 2300 STAT Plus glucose analyzer) and a hexokinase (cobas c111) method.

RESULTS

All 4 systems fulfilled the accuracy requirements of ISO 15197:2003 with the tested lots. More stringent accuracy criteria of ISO 15197:2013 were fulfilled by 3 systems (Accu-Chek Aviva, ContourXT, GlucoMen LX PLUS) when compared to the manufacturer's comparison method and by 2 systems (Accu-Chek Aviva, ContourXT) when compared to the alternative comparison method. All systems showed lot-to-lot variability to a certain degree; 2 systems (Accu-Chek Aviva, ContourXT), however, showed only minimal differences in relative bias between the 3 evaluated lots.

CONCLUSIONS

In this study, all 4 systems complied with the evaluated test strip lots with accuracy criteria of ISO 15197:2003. Applying ISO 15197:2013 accuracy limits, differences in the accuracy of the tested systems were observed, also demonstrating that the applied comparison method/system and the lot-to-lot variability can have a decisive influence on accuracy data obtained for a SMBG system.

Method for automatic adjustment of an insulin bolus calculator: in silico robustness evaluation under intra-day variability

BACKGROUND AND OBJECTIVE

Insulin bolus calculators are simple decision support software tools incorporated in most commercially available insulin pumps and some capillary blood glucose meters. Although their clinical benefit has been demonstrated, their utilisation has not been widespread and their performance remains suboptimal, mainly because of their lack of flexibility and adaptability. One of the difficulties that people with diabetes, clinicians and carers face when using bolus calculators is having to set parameters and adjust them on a regular basis according to changes in insulin requirements. In this work, we propose a novel method that aims to automatically adjust the parameters of a bolus calculator. Periodic usage of a continuous glucose monitoring device is required for this purpose.

METHODS

To test the proposed method, an in silico evaluation under real-life conditions was carried out using the FDA-accepted Type 1 diabetes mellitus (T1DM) UVa/Padova simulator. Since the T1DM simulator does not incorporate intra-subject variability and uncertainty, a set of modifications were introduced to emulate them. Ten adult and ten adolescent virtual subjects were assessed over a 3-month scenario with realistic meal variability. The glycaemic metrics: mean blood glucose; percentage time in target; percentage time in hypoglycaemia; risk index, low blood glucose index; and blood glucose standard deviation, were employed for evaluation purposes. A t-test statistical analysis was carried out to evaluate the benefit of the presented algorithm against a bolus calculator without automatic adjustment.

RESULTS

The proposed method statistically improved (p<0.05) all glycemic metrics evaluating hypoglycaemia on both virtual cohorts: percentage time in hypoglycaemia (i.e. BG<70 mg/dl) (adults: 2.7±4.0 vs. 0.4±0.7, p=0.03; adolescents: 7.1±7.4 vs. 1.3±2.4, p=0.02) and low blood glucose index (LBGI) (adults: 1.1±1.3 vs. 0.3±0.2, p=0.002; adolescents: 2.0±2.19 vs. 0.7±1.4, p=0.05). A statistically significant improvement was also observed on the blood glucose standard deviation (BG SD mg/dL) (adults: 33.5±13.7 vs. 29.2±8.3, p=0.01; adolescents: 63.7±22.7 vs. 44.9±23.9, p=0.01). Apart from a small increase in mean blood glucose on the adult cohort (129.9±11.9 vs. 133.9±11.6, p=0.03), the rest of the evaluated metrics, despite showing an improvement trend, did not experience a statistically significant change.

CONCLUSIONS

A novel method for automatically adjusting the parameters of a bolus calculator has the potential to improve glycemic control in T1DM diabetes management.

Monitoring glycemia in diabetes

Monitoring of glycemic control is a key component of the diabetes treatment plan. Patients who are not meeting targets often require more intensive monitoring, ranging from frequent self-monitored glucose to continuous glucose monitoring in order to facilitate medication and lifestyle changes. However, more intensive monitoring demands more training and a structured plan for interpretation and use of the data. Better patient and provider tools to support decision-making and progress toward an artificial pancreas may help to alleviate this burden.

Accuracy evaluation of blood glucose monitoring systems in children on overnight closed-loop control

This pilot study evaluated the difference in accuracy between the Bayer Contour® Next (CN) and HemoCue® (HC) glucose monitoring systems in children with type 1 diabetes participating in overnight closed-loop studies. Subjects aged 10-18 years old were admitted to a clinical research center and glucose values were obtained every 30 minutes overnight. Glucose values were measured using whole blood samples for CN and HC readings and results were compared to Yellow Springs Instrument (YSI) reference values obtained with plasma from the same sample. System accuracy was compared using mean absolute relative difference (MARD) and International Organization for Standardization (ISO) accuracy standards. A total of 28 subjects were enrolled in the study. Glucose measurements were evaluated at 457 time points. CN performed better than HC with an average MARD of 3.13% compared to 10.73% for HC (P < .001). With a limited sample size, CN met ISO criteria (2003 and 2013) at all glucose ranges while HC did not. CN performed very well, and would make an excellent meter for future closed-loop studies outside of a research center.

Self-monitoring of blood glucose in diabetes: from evidence to clinical reality in Central and Eastern Europe--recommendations from the international Central-Eastern European expert group

Self-monitoring of blood glucose (SMBG) is universally considered to be an integral part of type 1 diabetes management and crucial for optimizing the safety and efficacy of complex insulin regimens. This extends to type 2 diabetes patients on intensive insulin therapy, and there is also a growing body of evidence suggesting that structured SMBG is beneficial for all type 2 diabetes patients, regardless of therapy. However, access to SMBG can be limited in many countries in Central and Eastern Europe. A consensus group of diabetes experts from 10 countries in this region (with overlapping historical, political, and social environments)--Bulgaria, Croatia, Czech Republic, Hungary, Poland, Romania, Serbia, Slovakia, Slovenia, and Ukraine--was formed to discuss the role of SMBG across the spectrum of patients with diabetes. The group considered SMBG to be an essential tool that should be accessible to all patients with diabetes, including those with non-insulin-treated type 2 diabetes. The current article summarizes the evidence put forward by the consensus group and provides their recommendations for the appropriate use of SMBG as part of individualized patient management. The ultimate goal of these evidence-based recommendations is to help patients and providers in Central and Eastern Europe to make optimal use of SMBG in order to maximize the efficacy and safety of glucose-lowering therapies, to prevent complications, and to empower the patient to play a more active role in the management of their diabetes.