A glucose meter accuracy and precision comparison: the FreeStyle Flash Versus the Accu-Chek Advantage, Accu-Chek Compact Plus, Ascensia Contour, and the BD Logic

Reliability and accuracy of bedside capillary blood glucose measurement by glucometers compared to venous blood glucose in critically ill patients: A facility based cross-sectional study

BACKGROUND

The traditional reference standard, venous blood glucose requires venipuncture and laboratories usually return the test results after 60 min. Our aim was to determine the agreement accuracy of glucose (capillary) levels obtained by POC glucometers with glucose (venous) values by standard laboratory method (glucose-oxidase) and to assess whether and to what extent the glucometers perform uniformly well across the entire range of blood glucose values.

METHODS

We compared the diagnostic accuracy of two-point of care glucometers with laboratory venous glucose, the reference standard using Bland-Altman plots and Clark error grid method to analyse the results.

RESULTS

This study included a total of 110 patients (38[34 %] women; mean age 52.1 years (SD, 17.3); range 14-85 years. Fourteen patients (12 %) were known to have diabetes. The mean glucose value (glucometer 1) was 152.9 mg/dL (SD 83.1); range = 48-501 mg/dL; that by glucometer 2 was 152.2 mg/dL (SD 76.2); range = 30-458 mg/dL and by the laboratory was 148.6 mg/dL (SD 81.5); range = 52-480 mg/dL. Of the 110 subjects, 2(2 %) had blood glucose below 70 mg/dL; 85(77 %) between 70 and 180 mg/dL and 23(21 %) had blood glucose exceeding 180 mg/dL. The Bland-Altman plot showed a bias of 4 mg% (95%CI -9.8 to +1.1); and the limits of agreement were -63 and + 54 mg%. The area under the receiver operating characteristic curve for the two glucometers was 0.92 and 0.93 respectively.

CONCLUSIONS

Point of care glucose, measured by glucometers was in agreement with the venous glucose estimation. Both glucometers were equally accurate and performed uniformly well across the wide range of blood glucose values.

A Nanotechnology-Based Approach to Biosensor Application in Current Diabetes Management Practices

Diabetes mellitus is linked to both short-term and long-term health problems. Therefore, its detection at a very basic stage is of utmost importance. Research institutes and medical organizations are increasingly using cost-effective biosensors to monitor human biological processes and provide precise health diagnoses. Biosensors aid in accurate diabetes diagnosis and monitoring for efficient treatment and management. Recent attention to nanotechnology in the fast-evolving area of biosensing has facilitated the advancement of new sensors and sensing processes and improved the performance and sensitivity of current biosensors. Nanotechnology biosensors detect disease and track therapy response. Clinically efficient biosensors are user-friendly, efficient, cheap, and scalable in nanomaterial-based production processes and thus can transform diabetes outcomes. This article is more focused on biosensors and their substantial medical applications. The highlights of the article consist of the different types of biosensing units, the role of biosensors in diabetes, the evolution of glucose sensors, and printed biosensors and biosensing systems. Later on, we were engrossed in the glucose sensors based on biofluids, employing minimally invasive, invasive, and noninvasive technologies to find out the impact of nanotechnology on the biosensors to produce a novel device as a nano-biosensor. In this approach, this article documents major advances in nanotechnology-based biosensors for medical applications, as well as the hurdles they must overcome in clinical practice.

Effects of the Hydrophobicity of Key Residues on the Characteristics and Stability of Glucose Oxidase on a Graphene Surface

Glucose oxidase (GOx) is one of the most widely investigated enzymes in the field of bioelectrochemistry. It is mainly used for the detection of glucose in solutions and enzyme-based biofuel cells. On the basis of the combination of GOx with graphene, novel nanodevices exceeding conventional limits can be developed. To develop a hybrid enzyme-graphene nanodevice with a good performance, it is important that GOx is deposited well on the graphene surface while maintaining its structure and not impeding the oxidation activity of the GOx. In this study, we propose a method to improve the stability of GOx and secure its immobility on the graphene sheet and its glucose-binding affinity by single-point mutation of GOx using molecular dynamics simulations. We confirm that the structural stability, immobility, and substrate binding affinity of GOx can be modified by changing the hydrophobicity of a key residue. We demonstrate that biosensors or biofuel cells can be redesigned and their properties can be improved by using molecular dynamics simulation.

Familial aggregation and heritability of markers of metabolic risk, physical activity, and physical fitness in nuclear families from Muzambinho (Minas Gerais, Brazil)

OBJECTIVE

This study investigated the familial aggregation and heritability of markers of metabolic risk, physical activity, and physical fitness in nuclear families from Muzambinho (Minas Gerais, Brazil).

SUBJECTS AND METHODS

The study included members of 139 families, comprising 97 fathers (aged 40 ± 7 years), 129 mothers (35 ± 6 years), 136 sons (12 ± 4 years), and 121 daughters (12 ± 5 years). Evaluated markers included (A) body mass index, waist circumference, glycemia, and cholesterolemia, as metabolic risk markers; (B) total weekly volume of physical activity, as a physical activity marker; and (C) relative muscle strength, as a physical fitness marker. Correlations between family members and heritability (h2) were estimated using the software S.A.G.E.

RESULTS

Significant familial correlations were obtained between parents-offspring for glycemia and cholesterolemia (both ρ = 0.21, p < 0.05) and relative muscle strength (ρ = 0.23, p < 0.05), and between siblings for waist circumference, glycemia, total weekly volume of physical activity, and relative muscle strength (ρ variation 0.25 to 0.36, p < 0.05). Heritability values were significant for almost all variables (h2 variations: 20% to 57% for metabolic risk markers, 22% for the total weekly volume of physical activity, and 50% for relative muscle strength), except for waist circumference (h2 = 15%, p = 0.059).

CONCLUSION

The presence of significant correlations between family members and/or significant heritability strengthens the possible genetic and/or common familial environment influence on metabolic risk markers, total weekly volume of physical activity, and relative muscle strength.

Clinical Impact of Blood Glucose Monitoring Accuracy: An In-Silico Study

BACKGROUND

Patients with diabetes rely on blood glucose (BG) monitoring devices to manage their condition. As some self-monitoring devices are becoming more and more accurate, it becomes critical to understand the relationship between system accuracy and clinical outcomes, and the potential benefits of analytical accuracy.

METHODS

We conducted a 30-day in-silico study in type 1 diabetes mellitus (T1DM) patients using continuous subcutaneous insulin infusion (CSII) therapy and a variety of BG meters, using the FDA-approved University of Virginia (UVA)/Padova Type 1 Simulator. We used simulated meter models derived from the published characteristics of 43 commercial meters. By controlling random events in each parallel run, we isolated the differences in clinical performance that are directly associated with the meter characteristics.

RESULTS

A meter's systematic bias has a significant and inverse effect on HbA1c ( P < .01), while also affecting the number of severe hypoglycemia events. On the other hand, error, defined as the fraction of measurements beyond 5% of the true value, is a predictor of severe hypoglycemia events ( P < .01), but in the absence of bias has a nonsignificant effect on average glycemia (HbA1c). Both bias and error have significant effects on total daily insulin (TDI) and the number of necessary glucose measurements per day ( P < .01). Furthermore, these relationships can be accurately modeled using linear regression on meter bias and error.

CONCLUSIONS

Two components of meter accuracy, bias and error, clearly affect clinical outcomes. While error has little effect on HbA1c, it tends to increase episodes of severe hypoglycemia. Meter bias has significant effects on all considered metrics: a positive systemic bias will reduce HbA1c, but increase the number of severe hypoglycemia attacks, TDI use, and number of fingersticks per day.

Normal weight obesity among young adults in Trinidad and Tobago: prevalence and associated factors

BACKGROUND

Patients with normal weight obesity (NWO) have a normal body mass index (BMI) but elevated body fat percentage (BF%), thereby increasing their risk of cardiovascular and metabolic disorders. The purpose of this research was to determine the prevalence of NWO and its associated factors in a sample of young adults in Trinidad and Tobago (T&T).

METHODS

A cross sectional study involving a convenience non-voluntary sample of participants with a normal BMI of 18.5-24.9 kg/m2 was conducted. The following information was collected: history, basic anthropometric measurements, including BF% via the Tanita Ironman Body Composition Analyzer (BC554), physical examination and basic blood investigations. Participants were divided into two groups; normal BF% (<23.1% males, <33.3% females) and elevated BF% (≥23.1% males, ≥33.3% females).

RESULTS

Two hundred and thirty-six students participated, F:M (2.1:1), aged 18-28 years [Mean 21.33 (SD 2.5)], mean BMI 21.66 (SD 1.9). A response rate of 80.3%. The prevalence of NWO for this population was 19.9% [95% confidence interval (CI) 15.1-25.7]. Males 14.4% (95% CI 10.3-19.7) and females 5.5% (95% CI 3.1-9.5). Variables with a statistically significant association with NWO included gender, waist circumference, waist-to-hip ratio (WHR), systolic blood pressure (BP), the ratio of total cholesterol (TC) to high density lipoprotein and in females, the presence of polycystic ovarian syndrome (PCOS) (p<0.05). Binary logistic regression revealed that predictors of NWO were male gender and waist circumference.

CONCLUSIONS

One in five of this young adult population was found to have NWO. Long-term studies are recommended to study the full implications of these findings.

Masked hypoglycemia in pregnancy

BACKGROUND

Hypoglycemia is a major hindrance for optimal glycemic control in women with gestational diabetes mellitus (GDM) on insulin. In the present study, masked hypoglycemia (glucose <2.77mmol/L for ≥30 min) was estimated in pregnant women using a continuous glucose monitoring (CGM) system.

METHODS

Twenty pregnant women with GDM on insulin (cases) and 10 age-matched euglycemic pregnant women (controls) between 24 and 36 weeks gestation were recruited. Both groups performed self-monitoring of blood glucose (SMBG) and underwent CGM for 72 h to assess masked hypoglycemia. Masked hypoglycemic episodes were further stratified into two groups based on interstitial glucose (2.28-2.77 and ≤2.22 mmol/L).

RESULTS

Masked hypoglycemia was recorded in 35% (7/20) of cases and 40% (4/10) of controls using CGM, with an average of 1.28 and 1.25 episodes per subject, respectively. Time spent at glucose levels between 2.28 and 2.77 mmol/L did not differ between the two groups (mean 114 vs 90 min; P = 0.617), but cases spent a longer time with glucose ≤2.2 mmol/L. Babies born to women with GDM were significantly lighter than those born to controls (2860 vs 3290 g; P = 0.012). There was no significant difference in birth weight within the groups among babies born to women with or without hypoglycemia.

CONCLUSION

Euglycemic pregnant women and those with GDM on insulin had masked hypoglycemia. Masked hypoglycemia was not associated with adverse maternal or fetal outcomes. Therefore, low glucose levels in the hypoglycemic range may represent a physiologic adaptation in pregnancy. This response is exaggerated in women with GDM on insulin.

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.

Prevalence of Insulin Pump Therapy and Its Association with Measures of Glycemic Control: Results from the Canadian Study of Longevity in Type 1 Diabetes

OBJECTIVE

We aimed to determine cross-sectional insulin pump prevalence and factors associated with measures of glycemic control as a secondary analysis in a long-standing type 1 diabetes mellitus (T1DM) national cohort.

RESEARCH DESIGN AND METHODS

Canadian participants with ≥50 years of T1DM (n = 305) were administered a comprehensive mail-based questionnaire including acquisition of contemporaneous laboratory results. Factors associated with pump use, glycosylated hemoglobin (HbA1c), and hypoglycemia were analyzed by regression.

RESULTS

The 305 participants had a median age of 65 [interquartile range, 59, 71] years, median diabetes duration of 54 [51, 59] years, and mean HbA1c level of 7.5 ± 1.1%. Prevalence of pump use was 44% (133/305), with median duration of use 8 [4, 13] years. Compared with the non-pump subgroup, the pump subgroup had numerically lower but similar HbA1c levels (7.4 ± 0.9% vs. 7.6 ± 1.2%; P = 0.22) and reported greater numbers of minor hypoglycemia events (6.5 vs. 5.1 events/patient·month; P = 0.004) and fewer severe hypoglycemia events (0.5 vs. 1.3 events/patient·year; P = 0.02) in the past year. More frequent daily glucose tests and more frequent minor hypoglycemia events-but not pump therapy or its prescription parameters-were independently associated with lower HbA1c level in multivariable regression. However, use of insulin pump and habitual use of continuous glucose monitoring (≥1 week/month) were each independently associated with lower risk of severe hypoglycemia (risk ratio = 0.50 [P < 0.0001] and 0.30 [P = 0.001], respectively).

CONCLUSIONS

Insulin pump and continuous glucose monitoring technologies were associated with lower risk of severe hypoglycemia, while frequent daily glucose testing was associated with lower HbA1c level. These findings imply that basic self-management skill and technology play complementary roles in glycemic control among older adults with long-standing T1DM.

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.

Relationship between physical activity, physical fitness and multiple metabolic risk in youths from Muzambinho's study

Negative associations between physical activity (PA), physical fitness and multiple metabolic risk factors (MMRF) in youths from populations with low PA are reported. The persistence of this association in moderately-to highly active populations is not, however, well established. The aim of the present study was to investigate this association in a Brazilian city with high frequency of active youths. We assessed 122 subjects (9.9 ± 1.3 years) from Muzambinho city. Body mass index, waist circumference, glycaemia, cholesterolaemia, systolic and diastolic blood pressures were measured. Maximal handgrip strength and one-mile walk/run test were used. Leisure time PA was assessed by interview. Poisson regression was used in the analysis. The model explained 11% of the total variance. Only relative muscular strength and one-mile walk/run were statistically significant (p < .05). Those who needed more time to cover the one-mile walk/run test had an increased in metabolic risk of 11%, and those with greater strength reduced the risk by about 82%. In conclusion, children and youths from an active population who need less time to cover the one-mile walk/run test or who had greater muscular strength showed a reduced metabolic risk. These results suggest that even in children and youths with high leisure time PA, a greater aerobic fitness and strength might help to further reduce their MMRF.

Historical perspectives in clinical pathology: a history of glucose measurement

This is the second in the series of historical articles dealing with developments in clinical pathology. As one of the most commonly measured analytes in pathology, the assessment of glucose dates back to the time of the ancient Egyptians. It was only in the 19th century that advances in chemistry led to the identification of the sugar in urine being glucose. The following century witnessed the development of more chemical and enzymatic methods which became incorporated into the modern analysers and point-of-care instruments which are as ubiquitous as the modern day cellphones. Tracking the milestones in these developments shows the striking paradigms and the many parallels in the development of other clinical chemistry methods.

A blended- rather than whole-lentil meal with or without α-galactosidase mildly increases healthy adults' appetite but not their glycemic response

BACKGROUND

Disrupting the physical structure of pulses by blending them or by using a digestive supplement (α-galactosidase) to reduce intestinal discomfort could potentially negate the previously observed beneficial effects of whole pulses of lowering appetitive and glycemic responses because of more rapid digestion.

OBJECTIVE

We hypothesized that blended lentils, α-galactosidase, or both increase postprandial appetite and blood glucose responses vs. whole lentils.

METHODS

Men and women [n = 12; means ± SDs body mass index (kg/m(2)): 23.3 ± 3.1; aged 28 ± 10 y] consumed breakfast meals containing whole (W), blended (B), or no lentils [control (C)], each with 3 α-galactosidase or placebo capsules in a randomized, crossover, double-blind placebo-controlled trial. Between each test day there was a 3- to 5-d washout period.

RESULTS

Mixed-model ANOVA showed effects of meal on postprandial appetite and glucose (P = 0.0001-0.031). The B meal resulted in higher postprandial appetite ratings than did the W meal but not the C meal for hunger, desire to eat, and prospective consumption (Δ = 0.4-0.5 points; P = 0.002-0.044). Postprandial glucose concentration was 4.5 mg/dL lower for the B meal than for the C meal (P < 0.0001) but did not differ from the W meal. There were no main effects of α-galactosidase, but there were meal × α-galactosidase interaction effects, with a greater postprandial desire to eat and lower postprandial fullness with the B meal than with the 2 other meals in the placebo condition but not in the α-galactosidase condition.

CONCLUSIONS

Blending lentils increased appetite (∼6%), but not glycemic response, compared with whole lentils, whereas α-galactosidase did not. Both B and W meals may be consumed (with or without an α-galactosidase supplement) with little impact on appetite, without increasing glycemic response. This trial was registered at clinicaltrials.gov as NCT02110511.

Assessing the quality of publications evaluating the accuracy of blood glucose monitoring systems

Many studies determine the performance of blood glucose monitoring (BG) systems. Correct evaluation is, however, complex, and apparent contradiction of results creates confusion. This study aimed to provide an overview of frequently made errors and to develop easy-to-use checklists to verify the quality of such studies. Building on the work from Mahoney and Ellison and subsequent re-evaluation, study designs of accuracy studies were assessed, and best practice and internationally accepted norms were determined. Key issues were collated, and two simplified checklists were developed: one for the assessment of analytical accuracy studies and a second for guidance with studies assessing the influence of interferences. The checklists have been used in a feasibility study with 20 representative studies selected from a literature search between 2007 and 2012. This check revealed that limitations in the designs and methods of studies assessing the performance of BG systems are common. The use of the accuracy checklist with the 20 representative studies showed that only 20% were in agreement with most of the issues deemed important and that 40% showed clear nonconcordance with ISO 15197. The use of the interference checklist showed that only 50% of the publications were in good agreement with the quality checks. In agreement with previous studies, which concluded many evaluations are performed poorly and present questionable conclusions, the use of these checklists demonstrated that few publications adhered to international guidelines and recommendations. Taking this into consideration, it becomes obvious that the publications must be examined in more detail to establish their quality and the validity of conclusions drawn.

Fatigue in women with type 2 diabetes

PURPOSE

The purpose of this study was to explore the relationship between fatigue and physiological, psychological, and lifestyle phenomena in women with type 2 diabetes (T2DM) in order to establish the magnitude and correlates of fatigue in women with T2DM and explore the interrelationships between fatigue and specific diabetes-related factors that may be associated with increased levels of fatigue. These factors included physiological factors (glucose control, diabetes symptoms), psychological factors (diabetes emotional distress, depressive symptoms in general), and lifestyle factors (body mass index, physical activity).

METHODS

A cross-sectional, descriptive design was used. Women who reported conditions known to cause fatigue were excluded. Physiological measures included fasting blood glucose (FBG), hemoglobin A1C (A1C), glucose variability, and body mass index (BMI). Women completed questionnaires about health, fatigue levels, diabetes symptoms, diabetes emotional distress, depressive symptoms, physical activity, and current diabetes self-care practices. A subset of the women wore a Medtronic Gold CGM sensor for 3 days for assessment of glucose variability.

RESULTS

Eighty-three women aged 40 to 65 years with T2DM completed the study. Fatigue was significantly related to diabetes symptoms, diabetes emotional distress, depressive symptoms, higher BMI, and reduced physical activity. There was no relationship between fatigue and FBG or A1C. The strongest explanatory factors for fatigue were diabetes symptoms, depressive symptoms, and BMI, which accounted for 48% of the variance in fatigue scores. Glucose variability was not significantly associated with fatigue in these women.

CONCLUSIONS

Fatigue is a persistent clinical complaint among women with T2DM and may signal the presence of physiological, psychological, and lifestyle-related phenomena that could undermine diabetes health outcomes.

Accuracy of point-of-care glucose measurements

Control of blood glucose (BG) in an acceptable range is a major therapy target for diabetes patients in both the hospital and outpatient environments. This review focuses on the state of point-of-care (POC) glucose monitoring and the accuracy of the measurement devices. The accuracy of the POC glucose monitor depends on device methodology and other factors, including sample source and collection and patient characteristics. Patient parameters capable of influencing measurements include variations in pH, blood oxygen, hematocrit, changes in microcirculation, and vasopressor therapy. These elements alone or when combined can significantly impact BG measurement accuracy with POC glucose monitoring devices (POCGMDs). In general, currently available POCGMDs exhibit the greatest accuracy within the range of physiological glucose levels but become less reliable at the lower and higher ranges of BG levels. This issue raises serious safety concerns and the importance of understanding the limitations of POCGMDs. This review will discuss potential interferences and shortcomings of the current POCGMDs and stress when these may impact the reliability of POCGMDs for clinical decision-making.

Influência do índice glicêmico na glicemia em exercício físico aeróbico

OBJETIVO: Avaliar a influência do índice glicêmico (IG) na resposta glicêmica antes e durante o exercício físico decorrente a diferentes sessões experimentais pré-exercício. MÉTODOS: Doze homens adultos realizaram três sessões experimentais pré-exercício: de alto índice glicêmico (AIG); de baixo índice glicêmico (BIG); e em estado de jejum, sendo nesta última oferecida duas formas diferenciadas de hidratação durante o exercício: água e bebida carboidratada. RESULTADOS: Durante o período de repouso, o tipo de refeição, de AIG ou de BIG, interferiu no comportamento da glicemia, ambas tendendo ao "efeito rebote". Durante o exercício, não foi observada diferença na resposta glicêmica entre as quatro ações testadas; contudo, a intervenção com bebida carboidratada manteve constante a glicemia ao longo dos 60 min do exercício. CONCLUSÃO: O IG é determinante na resposta glicêmica ao longo de uma hora antes do exercício, porém não interfere na resposta glicêmica durante a atividade.

Performance of the CONTOUR® TS Blood Glucose Monitoring System

BACKGROUND

Self-monitoring of blood glucose (SMBG) remains an important component of diabetes management, engendering a need for affordable blood glucose (BG) meters that are accurate, precise, and convenient. The CONTOUR® TS is a BG meter that endeavors to meet this need. It uses glucose dehydrogenase/flavin dinucleotide chemistry, automatic test strip calibration, and autocompensation for hematocrit along with the ease of use that has come to be expected of a modern meter. The objective of this clinical trial was to determine whether the CONTOUR TS system met these criteria.

METHODS

The system was evaluated at a single clinical site with 106 subjects with type 1 or type 2 diabetes. Blood glucose values ranged from 60 to 333 mg/dl over all subjects. Both lay users and health care professionals (HCPs) tested the meters, with test strips from three different lots. Results were compared to a reference analyzer of verified precision and accuracy. Forty-nine of the subjects also participated in a home study of the meter. Lay users learned to use the system without assistance and were surveyed on its use at the end of the study.

RESULTS

When used with capillary blood, both subjects and HCPs obtained results that exceeded the International Organization for Standardization 15197:2003 criteria, (i.e., ≥95% of values fell within 20% or 15 mg/dl of the laboratory value for BG levels greater than or less than 75 mg/dl, respectively). Specifically, lay users achieved 97.9% and HCPs 98.6%. When used with venous blood, 99.8% of measurements were within the criteria. All measurements for both capillary and venous blood fell into zones A or B of the Parkes error grid, deemed clinically accurate. Hematocrit was found to have no influence on BG measurements. A large majority of the subjects found the system easy to learn and to use.

CONCLUSIONS

The CONTOUR TS BG meter system gave accurate and reproducible results with both capillary and venous blood; subjects learned to use the meter system by following the user guide and quick reference guide.

Transcutaneous glucose sensing by surface-enhanced spatially offset Raman spectroscopy in a rat model

This letter presents the first quantitative, in vivo, transcutaneous glucose measurements using surface enhanced Raman spectroscopy (SERS). Silver film over nanosphere (AgFON) surfaces were functionalized with a mixed self-assembled monolayer (SAM) and implanted subcutaneously in a Sprague-Dawley rat. The glucose concentration was monitored in the interstitial fluid. SER spectra were collected from the sensor chip through the skin using spatially offset Raman spectroscopy (SORS). The combination of SERS and SORS is a powerful new approach to the challenging problem of in vivo metabolite and drug sensing.

Review article: glucose measurement in the operating room: more complicated than it seems

Abnormalities of blood glucose are common in patients undergoing surgery, and in recent years there has been considerable interest in tight control of glucose in the perioperative period. Implementation of any regime of close glycemic control requires more frequent measurement of blood glucose, a function for which small, inexpensive, and rapidly responding point-of-care devices might seem highly suitable. However, what is not well understood by many anesthesiologists and other staff caring for patients in the perioperative period is the lack of accuracy of home glucose meters that were designed for self-monitoring of blood glucose by patients. These devices have been remarketed to hospitals without appropriate additional testing and without an appropriate regulatory framework. Clinicians who are accustomed to the high level of accuracy of glucose measurement by a central laboratory device or by an automated blood gas analyzer may be unaware of the potential for harmful clinical errors that are caused by the inaccuracy exhibited by many self-monitoring of blood glucose devices, especially in the hypoglycemic range. Knowledge of the limitations of these meters is essential for the perioperative physician to minimize the possibility of a harmful measurement error. In this article, we will highlight these areas of interest and review the indications, technology, accuracy, and regulation of glucose measurement devices used in the perioperative setting.

Glycemic control in the burn intensive care unit: focus on the role of anemia in glucose measurement

Glycemic control with intensive insulin therapy (IIT) has received widespread adoption secondary to findings of improved clinical outcomes and survival in the burn population. Severe burn as a model for trauma is characterized by a hypermetabolic state, hyperglycemia, and insulin resistance. In this article, we review the findings of a burn center research facility in terms of understanding glucose management. The conferred benefits from IIT, our findings of poor outcomes associated with glycemic variability, advantages from preserved diurnal variation of glucose and insulin, and impacts of glucometer error and hematocrit correction factor are discussed. We conclude with direction for further study and the need for a reliable continuous glucose monitoring system. Such efforts will further the endeavor for achieving adequate glycemic control in order to assess the efficacy of target ranges and use of IIT.

Clinical performance of the TRUE2go blood glucose system--a novel integrated system for meter and strips

BACKGROUND

The complications of diabetes may be minimized by adequate glycemic control, which is aided by self-monitoring of blood glucose (SMBG) levels. A new SMBG system, TRUE2go (Home Diagnostics, Inc., Fort Lauderdale, FL), does not require calibration of test strips, thereby eliminating the potential source of error in blood glucose determination associated with mis-calibration. This study tested the performance of the TRUE2go system. The very small size and attachment of the meter to a vial of test strips make the TRUE2go system unique.

METHODS

The studies were carried out with adult patients with type 1 or 2 diabetes, using procedures for testing accuracy as specified in International Organization for Standardization (ISO) 15197:2003. The evaluation included patients' compliance with the TRUE2go system's written instructions, ease of understanding the supplied instructions, and ease of use of the system.

RESULTS

The study demonstrated the accuracy and precision of the TRUE2go system, with 100% of glucose test results falling within ISO-recommended limits for glucose concentrations ranging from 24 mg/dL to 549 mg/dL. There was agreement between data obtained with TRUE2go when used by healthcare professionals and by lay users on capillary blood from both fingertip and a forearm sticks. Lay users' understanding of and compliance with TRUE2go system instructions were excellent, as was their satisfaction with the system.

CONCLUSIONS

The TRUE2go system is accurate and convenient to use, and its instructions are easily understood by lay users. TRUE2go features that contribute to convenience, and therefore could improve compliance with monitoring regimens, include its small size, attachment to the vial of strips, easy-to-read display, automatic calibration for test strips, and suitability for fingertip as well as forearm testing.

Accuracy and precision of four value-added blood glucose meters: the Abbott Optium, the DDI Prodigy, the HDI True Track, and the HypoGuard Assure Pro

PURPOSE

This study compared the accuracy and precision of four value-added glucose meters.

METHODS

Finger stick glucose measurements in diabetes patients were performed using the Abbott Diabetes Care (Alameda, CA) Optium, Diagnostic Devices, Inc. (Miami, FL) DDI Prodigy, Home Diagnostics, Inc. (Fort Lauderdale, FL) HDI True Track Smart System, and Arkray, USA (Minneapolis, MN) HypoGuard Assure Pro. Finger glucose measurements were compared with laboratory reference results. Accuracy was assessed by a Clarke error grid analysis (EGA), a Parkes EGA, and within 5%, 10%, 15%, and 20% of the laboratory value criteria (chi2 analysis). Meter precision was determined by calculating absolute mean differences in glucose values between duplicate samples (Kruskal-Wallis test).

RESULTS

Finger sticks were obtained from 125 diabetes patients, of which 90.4% were Caucasian, 51.2% were female, 83.2% had type 2 diabetes, and average age of 59 years (SD 14 years). Mean venipuncture blood glucose was 151 mg/dL (SD +/-65 mg/dL; range, 58-474 mg/dL). Clinical accuracy by Clarke EGA was demonstrated in 94% of Optium, 82% of Prodigy, 61% of True Track, and 77% of the Assure Pro samples (P < 0.05 for Optium and True Track compared to all others). By Parkes EGA, the True Track was significantly less accurate than the other meters. Within 5% accuracy was achieved in 34%, 24%, 29%, and 13%, respectively (P < 0.05 for Optium, Prodigy, and Assure Pro compared to True Track). Within 10% accuracy was significantly greater for the Optium, Prodigy, and Assure Pro compared to True Track. Significantly more Optium results demonstrated within 15% and 20% accuracy compared to the other meter systems. The HDI True Track was significantly less precise than the other meter systems.

CONCLUSIONS

The Abbott Optium was significantly more accurate than the other meter systems, whereas the HDI True Track was significantly less accurate and less precise compared to the other meter systems.

Glucose meters: a review of technical challenges to obtaining accurate results

Glucose meters are universally utilized in the management of hypoglycemic and hyperglycemic disorders in a variety of healthcare settings. Establishing the accuracy of glucose meters, however, is challenging. Glucose meters can only analyze whole blood, and glucose is unstable in whole blood. Technical accuracy is defined as the closeness of agreement between a test result and the true value of that analyte. Truth for glucose is analysis by isotope dilution mass spectrometry, and frozen serum standards analyzed by this method are available from the National Institute of Standards and Technology. Truth for whole blood has not been established, and cells must be separated from the whole blood matrix before analysis by a method like isotope dilution mass spectrometry. Serum cannot be analyzed by glucose meters, and isotope dilution mass spectrometry is not commonly available in most hospitals and diabetes clinics to evaluate glucose meter accuracy. Consensus standards recommend comparing whole blood analysis on a glucose meter against plasma/serum centrifuged from a capillary specimen and analyzed by a clinical laboratory comparative method. Yet capillary samples may not provide sufficient volume to test by both methods, and venous samples may be used as an alternative when differences between venous and capillary blood are considered. There are thus multiple complexities involved in defining technical accuracy and no clear consensus among standards agencies and professional societies on accuracy criteria. Clinicians, however, are more concerned with clinical agreement of the glucose meter with a serum/plasma laboratory result. Acceptance criteria for clinical agreement vary across the range of glucose concentrations and depend on how the result will be used in screening or management of the patient. A variety of factors can affect glucose meter results, including operator technique, environmental exposure, and patient factors, such as medication, oxygen therapy, anemia, hypotension, and other disease states. This article reviews the challenges involved in obtaining accurate glucose meter results.