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

Colorimetric sensing for translational applications: from colorants to mechanisms

Colorimetric sensing offers instant reporting via visible signals. Versus labor-intensive and instrument-dependent detection methods, colorimetric sensors present advantages including short acquisition time, high throughput screening, low cost, portability, and a user-friendly approach. These advantages have driven substantial growth in colorimetric sensors, particularly in point-of-care (POC) diagnostics. Rapid progress in nanotechnology, materials science, microfluidics technology, biomarker discovery, digital technology, and signal pattern analysis has led to a variety of colorimetric reagents and detection mechanisms, which are fundamental to advance colorimetric sensing applications. This review first summarizes the basic components (e.g., color reagents, recognition interactions, and sampling procedures) in the design of a colorimetric sensing system. It then presents the rationale design and typical examples of POC devices, e.g., lateral flow devices, microfluidic paper-based analytical devices, and wearable sensing devices. Two highlighted colorimetric formats are discussed: combinational and activatable systems based on the sensor-array and lock-and-key mechanisms, respectively. Case discussions in colorimetric assays are organized by the analyte identities. Finally, the review presents challenges and perspectives for the design and development of colorimetric detection schemes as well as applications. The goal of this review is to provide a foundational resource for developing colorimetric systems and underscoring the colorants and mechanisms that facilitate the continuing evolution of POC sensors.

Biosensors for Public Health and Environmental Monitoring: The Case for Sustainable Biosensing

Climate change is a profound crisis that affects every aspect of life, including public health. Changes in environmental conditions can promote the spread of pathogens and the development of new mutants and strains. Early detection is essential in managing and controlling this spread and improving overall health outcomes. This perspective article introduces basic biosensing concepts and various biosensors, including electrochemical, optical, mass-based, nano biosensors, and single-molecule biosensors, as important sustainability and public health preventive tools. The discussion also includes how the sustainability of a biosensor is crucial to minimizing environmental impacts and ensuring the long-term availability of vital technologies and resources for healthcare, environmental monitoring, and beyond. One promising avenue for pathogen screening could be the electrical detection of biomolecules at the single-molecule level, and some recent developments based on single-molecule bioelectronics using the Scanning Tunneling Microscopy-assisted break junctions (STM-BJ) technique are shown here. Using this technique, biomolecules can be detected with high sensitivity, eliminating the need for amplification and cell culture steps, thereby enhancing speed and efficiency. Furthermore, the STM-BJ technique demonstrates exceptional specificity, accurately detects single-base mismatches, and exhibits a detection limit essentially at the level of individual biomolecules. Finally, a case is made here for sustainable biosensors, how they can help, the paradigm shift needed to achieve them, and some potential applications.

Teaching Medical Devices through Interactive Innovation: Challenges and Rewards

Medical devices are manmade objects existing at the interface between numerous disciplines. They range from as simple as medical gloves to as complex as artificial limbs. This versatility of medical devices and their inherent interdisciplinary nature means that academic courses on them are attended by cohorts of students from varieties of academic backgrounds, who bring with them similarly broad spectra of interests. To satisfy the learning expectations of each and every student in such diverse classes is a daunting task for the instructor. After many years of teaching medical devices at undergraduate and graduate levels at three different universities in the states of Illinois and California, I have come up with an instructional method that solves this challenge by engaging students in the co-creation of the curriculum via selection of their own medical devices of interest and presentation to the class for collective analysis. The threefold presentations are designed so that they reflect an ascent along the hierarchy of a learning taxonomy extending from foundational concepts to critical assessment of knowledge to creative displays of it. In such a way, the students are acquainted with the ability of critical and creative thinking at the expense of rote memorization or inculcation and are prepared to enter the field of medical devices as innovation-centered individuals. The specifics of this new method of instruction are reported here, with the hope that they will be useful to fellow instructors in any interdisciplinary course that benefits from a balance between the rigorous coverage of the instructional material pertaining to engineering and medicine and the flexible selection of topics that comply with students' individual interests.

Precision and accuracy of a point of care glucometer for detection of hypoglycaemia in horses

Point-of-care (POC) glucometry is commonly used in horses; however, measurement error with this method when analysing hypoglycaemic samples (<4 mmol/L) is unknown. The objective of this study was to determine the precision and accuracy of glucometry in hypoglycaemic horses in comparison to a laboratory method of glucose measurement (LAB). Repeatability coefficients were 0.47 mmol/L for POC and 0.09 mmol/L for LAB, and coefficients of variation were 10 % and 2.11 %, for the POC and LAB methods, respectively. Systemic bias with the POC method was present, with a mean bias of -0.26 mmol/L (95 % limits of agreement: -0.88 - 0.37) in comparison to LAB, and <70% of measurements were within 20 % of paired LAB results. Prior to use of glucometers, assessment of the diagnostic performance of the equipment is necessary, including determination of acceptable criteria and reference ranges for hypoglycaemic samples.

Mechanical Robustness Enhanced Flexible Antennas Using Ti3C2 MXene and Nanocellulose Composites for Noninvasive Glucose Sensing

Electromagnetic sensors with flexible antennas as sensing elements have attracted increasing attention in noninvasive continuous glucose monitoring for diabetic patients. The significant radiation performance loss of flexible antennas during mechanical deformation impairs the reliability of glucose monitoring. Here, we present flexible ultrawideband monopole antennas composed of Ti3C2 MXene and cellulose nanofibril (CNF) composite films for continuous glucose monitoring. The flexible MXene/CNF antenna with 20% CNF content can obtain a gain of up to 3.33 dBi and a radiation efficiency of up to 65.40% at a frequency range from 2.3 to 6.0 GHz. Compared with the pure MXene antenna, this antenna offers a comparable radiation performance and a lower performance loss in mechanical bending deformation. Moreover, the MXene/CNF antenna shows a stable response to fetal bovine serum/glucose, with a correlation of >0.9 at the reference glucose levels, and responds sensitively to the variations in blood glucose levels during human trials. The proposed strategy enhancing the mechanical robustness of MXene-based flexible antennas makes metallic two-dimensional nanomaterials more promising in wearable electromagnetic sensors.

Extended Review Concerning the Integration of Electrochemical Biosensors into Modern IoT and Wearable Devices

Electrochemical biosensors include a recognition component and an electronic transducer, which detect the body fluids with a high degree of accuracy. More importantly, they generate timely readings of the related physiological parameters, and they are suitable for integration into portable, wearable and implantable devices that are significant relative to point-of-care diagnostics scenarios. As an example, the personal glucose meter fundamentally improves the management of diabetes in the comfort of the patients' homes. This review paper analyzes the principles of electrochemical biosensing and the structural features of electrochemical biosensors relative to the implementation of health monitoring and disease diagnostics strategies. The analysis particularly considers the integration of the biosensors into wearable, portable, and implantable systems. The fundamental aim of this paper is to present and critically evaluate the identified significant developments in the scope of electrochemical biosensing for preventive and customized point-of-care diagnostic devices. The paper also approaches the most important engineering challenges that should be addressed in order to improve the sensing accuracy, and enable multiplexing and one-step processes, which mediate the integration of electrochemical biosensing devices into digital healthcare scenarios.

Correlational analysis between salivary and blood glucose levels in individuals with and without diabetes mellitus: a cross-sectional study

OBJECTIVE

To estimate the association of patient-related demographic, socioeconomic status, physical activity, stress, and dietary factors influencing the relationship between salivary and blood glucose levels in individuals with and without diabetes mellitus (DM).

METHOD

This cross-sectional study was conducted on 166 participants with and without DM. Saliva and blood were collected to estimate the glucose levels. Age, gender, occupation, socioeconomic and education level, BMI, hip to waist circumference, stress, dietary pattern, lifestyle, physical activity, family history of diabetes, and type of diabetes were recorded. The association of saliva to predict blood glucose levels was analysed using Spearman Rank Correlation and how these patient-related factors influence the correlation was estimated for future machine learning models. The difference in medians for various groups was calculated using the Mann-Whitney U Test or Kruskal Wallis Test.

RESULTS

Blood glucose level is not significantly correlated to salivary glucose level. However, a statistically significant difference in the median blood glucose levels for diabetic participants (median = 137) compared to healthy controls (p-value < .05) was noted. The correlation between blood and salivary glucose was more positive for higher levels of glucose (Spearman 0.4). Age, alcohol consumption, monthly wages, intake of vegetables, and socioeconomic status affect blood glucose levels.

CONCLUSION

A correlation between saliva and blood glucose levels in healthy individuals was weak. Saliva should only be used as a monitoring tool rather than a diagnostic tool and is more reliable for patients with poorly controlled diabetes mellitus.

Impedance-based polymer microneedle patch sensor for continuous interstitial fluid glucose monitoring

Early detection and effective blood glucose control are critical for preventing and managing diabetes-related complications. Conventional glucometers provide point-in-time measurements but are painful and cannot facilitate continuous monitoring. Continuous glucose monitoring systems are comfortable but face challenges in terms of accuracy, cost, and sensor lifespan. This study aimed to develop a microneedle-based sensor patch for minimally invasive, painless, and continuous glucose monitoring in the interstitial fluid to address these limitations. Experimental results confirm painless and minimally invasive penetration of the skin tissue with cylindrical microneedles (3 × 3 array) to a depth of approximately 520 μm with minimal loading. The microneedle sensors fabricated with precision using the complementary metal-oxide semiconductor process were immobilized with glucose oxidase, as confirmed through phase angle analysis. Long-term tests confirmed the effective operation of the sensor for up to seven days. Glucose concentrations determined from the fitted concentration-impedance curves correlated well with those measured using commercial glucometers, indicating the reliability and precision of the microneedle sensor. The flexible and minimally invasive sensor developed in this study facilitates painless and continuous glucose monitoring.

Exploring the Potentials of Chitin and Chitosan-Based Bioinks for 3D-Printing of Flexible Electronics: The Future of Sustainable Bioelectronics

Chitin and chitosan-based bioink for 3D-printed flexible electronics have tremendous potential for innovation in healthcare, agriculture, the environment, and industry. This biomaterial is suitable for 3D printing because it is highly stretchable, super-flexible, affordable, ultrathin, and lightweight. Owing to its ease of use, on-demand manufacturing, accurate and regulated deposition, and versatility with flexible and soft functional materials, 3D printing has revolutionized free-form construction and end-user customization. This study examined the potential of employing chitin and chitosan-based bioinks to build 3D-printed flexible electronic devices and optimize bioink formulation, printing parameters, and postprocessing processes to improve mechanical and electrical properties. The exploration of 3D-printed chitin and chitosan-based flexible bioelectronics will open new avenues for new flexible materials for numerous industrial applications.

Hierarchical Nanobiosensors at the End of the SARS-CoV-2 Pandemic

Nanostructures have played a key role in the development of different techniques to attack severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Some applications include masks, vaccines, and biosensors. The latter are of great interest for detecting diseases since some of their features allowed us to find specific markers in secretion samples such as saliva, blood, and even tears. Herein, we highlight how hierarchical nanoparticles integrated into two or more low-dimensional materials present outstanding advantages that are attractive for photonic biosensing using their nanoscale functions. The potential of nanohybrids with their superlative mechanical characteristics together with their optical and optoelectronic properties is discussed. The progress in the scientific research focused on using nanoparticles for biosensing a variety of viruses has become a medical milestone in recent years, and has laid the groundwork for future disease treatments. This perspective analyzes the crucial information about the use of hierarchical nanostructures in biosensing for the prevention, treatment, and mitigation of SARS-CoV-2 effects.

Investigating the characteristics of health-related data collection tools used in randomised controlled trials in low-income and middle-income countries: protocol for a systematic review

INTRODUCTION

Health-related data collection tools, including digital ones, have become more prevalent across clinical studies in the last number of years. However, using digital data collection tools in low-income and middle-income countries presents unique challenges. In this review, we aim to provide an overview of the data collection tools currently being used in randomised controlled trials (RCTs) conducted in low-resource settings and evaluate the tools based on the characteristics outlined in the modified Mobile Survey Tool framework. These include functionality, reliability, usability, efficiency, maintainability, portability, effectiveness, cost-benefit, satisfaction, freedom from risk and context coverage. This evidence may provide a guide to selecting a suitable data collection tool for researchers planning to conduct research in low-income and middle-income countries for future studies.

METHODS AND ANALYSIS

Searches will be conducted in four electronic databases: PubMed, CINAHL, Web of Science and EMBASE. For inclusion, studies must be a RCT, mention a health-related data collection tool and conducted in a low- and middle-income country. Only studies with available full-text and written in English will be included. The search was restricted to studies published between January 2005 and June 2023. This systematic review will use the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) tool. Two review authors will screen the titles and abstracts of search results independently for inclusion. In the initial screening process, the full-text articles will be retrieved if the abstract contains limited information about the study. Disagreements will be resolved through discussion. If the disagreement cannot be resolved, a third author (JO'D) will adjudicate. The study selection process will be outlined in a PRISMA flow-diagram. Data will be analysed using a narrative synthesis approach. The included studies and their outcomes will be presented in a table.

ETHICS AND DISSEMINATION

Formal ethical approval is not required as primary data will not be collected in this study. The findings from this systematic review will be published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42023405738.

MOF-based nanocomposites as transduction matrices for optical and electrochemical sensing

Metal Organic Frameworks (MOFs), a class of crystalline microporous materials have been into research limelight lately due to their commendable physio-chemical properties and easy fabrication methods. They have enormous surface area which can be a working ground for innumerable molecule adhesions and site for potential sensor matrices. Their biocompatibility makes them valuable for in vitro detection systems but a compromised conductivity requires a lot of surface engineering of these molecules for their usage in electrochemical biosensors. However, they are not just restricted to a single type of transduction system rather can also be modified to achieve feat as optical (colorimetry, luminescence) and electro-luminescent biosensors. This review emphasizes on recent advancements in the area of MOF-based biosensors with focus on various MOF synthesis methods and their general properties along with selective attention to electrochemical, optical and opto-electrochemical hybrid biosensors. It also summarizes MOF-based biosensors for monitoring free radicals, metal ions, small molecules, macromolecules and cells in a wide range of real matrices. Extensive tables have been included for understanding recent trends in the field of MOF-composite probe fabrication. The article sums up the future scope of these materials in the field of biosensors and enlightens the reader with recent trends for future research scope.

Electrochemical Aptamer-Based Biosensors for Measurements in Undiluted Human Saliva

Although blood remains a gold standard diagnostic fluid for most health exams, it involves an unpleasant and relatively invasive sampling procedure (finger pricking or venous draw). Saliva contains many relevant and useful biomarkers for diagnostic purposes, and its collection, in contrast, is noninvasive and can be obtained with minimal effort. Current saliva analyses are, however, achieved using chromatography or lateral flow assays, which, despite their high accuracy and sensitivity, can demand expensive laboratory-based instruments operated by trained personnel or offer only semiquantitative results. In response, we investigated electrochemical aptamer-based (E-AB) biosensors, a reagentless sensing platform, to allow for continuous and real-time measurements directly in undiluted, unstimulated human whole saliva. As a proof-of-concept study, we developed E-AB biosensors capable of detecting low-molecular-weight analytes (glucose and adenosine monophosphate (AMP)). To our knowledge, we report the first E-AB sensor for glucose, an approach that is inherently independent of its chemical reactivity in contrast to home glucometers. For these three sensors, we evaluated their figures of merits, stability, and reusability over short- and long-term exposure directly in saliva. In doing so, we found that E-AB sensors allow rapid and convenient molecular measurements in whole saliva with unprecedented sensitivities in the pico- to nanomolar regime and could be regenerated and reused up to 7 days when washed and stored in phosphate-buffered saline at room temperature. We envision that salivary molecular measurements using E-AB sensors are a promising alternative to invasive techniques and can be used for improved point-of-care clinical diagnosis and at-home measurements.

Glucose oxidase-instructed biomineralization of calcium-based biomaterials for biomedical applications

In recent years, glucose oxidase (GOx) has aroused great research interest in the treatment of diseases related to abnormal glucose metabolisms like cancer and diabetes. However, as a kind of endogenous oxido-reductase, GOx suffers from poor stability and system toxicity in vivo. In order to overcome this bottleneck, GOx is encapsulated in calcium-based biomaterials (CaXs) such as calcium phosphate (CaP) and calcium carbonate (CaCO3) by using it as a biotemplate to simulate the natural biomineralization process. The biomineralized GOx holds improved stability and reduced side effects, due to the excellent bioactivity, biocompatibitliy, and biodegradability of CaXs. In this review, the state-of-the-art studies on GOx-mineralized CaXs are introduced with an emphasis on their application in various biomedical fields including disease diagnosis, cancer treatment, and diabetes management. The current challenges and future perspectives of GOx-mineralized CaXs are discussed, which is expected to promote further studies on these smart GOx-mineralized CaXs biomaterials for practical applications.

Glucose Oxidase Loading in Ordered Porous Aluminosilicates: Exploring the Potential of Surface Modification for Electrochemical Glucose Sensing

Enzymatic electrochemical sensors have become the leading glucose detection technology due to their rapid response, affordability, portability, selectivity, and sensitivity. However, the performance of these sensors is highly dependent on the surface properties of the electrode material used to store glucose oxidase and its ability to retain enzymatic activity under variable environmental conditions. Mesoporous thin films have recently attracted considerable attention as promising candidates for enzyme storage and activity preservation due to their well-defined nanoarchitecture and tunable surface properties. Herein, we systematically compare pathways for the immobilization of glucose oxidase (GOx) and their effectiveness in electrochemical glucose sensing, following modification protocols that lead to the electrostatic attraction (amino functionalization), covalent bonding (aldehyde functionalization), and electrostatic repulsion (oxygen plasma treatment) of the ordered porous aluminosilicate-coated electrodes. By direct comparison using a quartz crystal microbalance, we demonstrate that glucose oxidase can be loaded in a nanoarchitecture with a pore size of ∼50 nm and pore interconnections of ∼35 nm using the native aluminosilicate surface, as well as after amino or aldehyde surface modification, while oxygen plasma exposure of the native surface inhibits glucose oxidase loading. Despite a variety of routes for enzyme loading, quantitative electrochemical glucose sensing between 0 and 20 mM was only possible when the porous surface was functionalized with amino groups, which we relate to the role of surface chemistry in accessing the underlying substrate. Our results highlight the impact of rational surface modification on electrochemical biosensing performance and demonstrate the potential of tailoring porous nanoarchitecture surfaces for biosensing applications.

Accuracy of Point-of-Care Blood Glucometers in Neonates and Critically Ill Adults

PURPOSE

Inpatient glycemic management has become a common issue because of the increasing number of hospitalized patients with hyperglycemia. Point-of-care devices can enable timely inpatient glucose monitoring, which may lead to better outcomes. The accuracy of point-of-care testing in various clinical scenarios has been questioned, particularly in neonates and critically ill patients. This study aimed to evaluate the accuracy of the CONTOUR PLUS and CONTOUR PLUS ONE glucometers (new wireless systems that link to a smart mobile device) when used as point-of-care devices for blood glucose monitoring in neonates and critically ill adults in inpatient settings.

METHODS

This cross-sectional study was conducted at a medical center in central Taiwan and enrolled patients admitted to the neonatal intensive care unit, sick child room, or respiratory intensive care unit between November 2020 and April 2021. Neonates with suspected infection or abnormal blood coagulation and adults who had abnormal blood coagulation, were pregnant, had received organ transplants, or had undergone massive blood transfusions were excluded. The accuracy of the glucometers was determined based on the following criteria of the International Organization for Standardization (ISO) standard: 15197:2013.

FINDINGS

Overall, 114 neonates (mean age, 4.2 days [range, 0-28 days]; 65 boys [57.0%]) and 106 hospitalized critically ill adults (mean age, 68.2 years [range, 27-94 years]; 72 men [67.9%]) were enrolled in this study. The glucose values obtained with each glucometer had good precision, and all findings met the reference criteria of the within-lot results. All measurements of the neonates' venous blood by each glucometer met the accuracy criteria specified by ISO standard 15197:2013. Furthermore, 98.1% and 97.2% of the arterial blood glucose measurements for critically ill adults obtained with CONTOUR PLUS and CONTOUR PLUS ONE met the accuracy criteria, respectively.

IMPLICATIONS

Both glucose management systems met the accuracy criteria for venous blood from neonates and arterial blood from critically ill adults. Thus, the use of these 2 point-of-care devices in inpatient settings, including for neonates and critically ill adults, can be recommended to minimize limitations associated with the clinical application of point-of-care testing in glucose management. The wireless connection may play a role in the subsequent development of institution-wide virtual glycemic management under the supervision of a team of endocrinologists.

Achievement of Target Glycemic Goal with Simple Basal Insulin Regimen in Women with Gestational Diabetes: A Prospective Cohort Study

There is little evidence concerning the need to treat gestational diabetes (GDM) in the same way as pregestational diabetes. We evaluated the efficacy of the simple insulin injection (SII) regimen for achieving the target glucose goal without increasing adverse perinatal outcomes in singleton pregnant women with GDM. All subjects underwent self-monitoring of blood glucose (SMBG), and insulin therapy was indicated according to the SMBG profile. Insulin was initially started with the SII regimen, in which one daily injection of NPH insulin before breakfast was used, and another NPH injection was added at bedtime, if necessary. We used the target glucose as <95 mg/dL at fasting and <120 mg/dL postprandial and accepted <130 mg/dL for the latter. If the target glucose did not reach with the regimen, we switched to the multiple daily injection (MDI) with additional prandial insulin aspart. We compared the SMBG profile before delivery as well as the perinatal outcomes between the SII and MDI groups. Among 361 women (age 33.7 years, nullipara 41%, prepregnancy body mass index 23.2 kg/m²) with GDM, 59%, 18%, and 23% were in the diet-alone, SII, and MDI groups, respectively. Consequently, regarding women requiring insulin therapy, 43% were treated with the SII regimen throughout pregnancy. The severity of baseline hyperglycemia according to the SMBG data at baseline was the MDI>the SII>the diet group. The rate of achieving target glucose levels before delivery in the SII group at fasting, postprandial < 120 mg/dL and <130 mg/dL were 93%, 54% and 87%, respectively, which were similar to that in the MDI group (93%, 57%, and 93%, respectively), with no significant differences in perinatal outcomes. In conclusion, more than 40% of women with GDM requiring insulin therapy achieved the target glucose goal with this simple insulin regimen without any increase in adverse effects.

Progress on the influence of non-enzymatic electrodes characteristics on the response to glucose detection: a review (2016–2022)

Glucose sensing devices have experienced significant progress in the last years in response to the demand for cost-effective monitoring. Thus, research efforts have been focused on achieving reliable, selective, and sensitive sensors able to monitor the glucose level in different biofluids. The development of enzyme-based devices is challenged by poor stability, time-consuming, and complex purification procedures, facts that have given rise to the synthesis of enzyme-free sensors. Recent advances focus on the use of different components: metal-organic frameworks (MOFs), carbon nanomaterials, or metal oxides. Motivated by this topic, several reviews have been published addressing the sensor materials and synthesis methods, gathering relevant information for the development of new nanostructures. However, the abundant information has not concluded yet in commercial devices and is not useful from an engineering point of view. The dependence of the electrode response on its physico-chemical nature, which would determine the selection and optimization of the materials and synthesis method, remains an open question. Thus, this review aims to critically analyze from an engineering vision the existing information on non-enzymatic glucose electrodes; the analysis is performed linking the response in terms of sensitivity when interferences are present, stability, and response under physiological conditions to the electrode characteristics.

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.

Device integration of electrochemical biosensors

Electrochemical biosensors incorporate a recognition element and an electronic transducer for the highly sensitive detection of analytes in body fluids. Importantly, they can provide rapid readouts and they can be integrated into portable, wearable and implantable devices for point-of-care diagnostics; for example, the personal glucose meter enables at-home assessment of blood glucose levels, greatly improving the management of diabetes. In this Review, we discuss the principles of electrochemical biosensing and the design of electrochemical biosensor devices for health monitoring and disease diagnostics, with a particular focus on device integration into wearable, portable and implantable systems. Finally, we outline the key engineering challenges that need to be addressed to improve sensing accuracy, enable multiplexing and one-step processes, and integrate electrochemical biosensing devices in digital health-care pathways.

Point of care blood glucose devices in the hospital setting

Dysglycemia is common among hospitalized patients. Accurate point-of-care (POC) glucose monitoring is necessary for the safe administration of insulin. Unfortunately, POC glucose meters are not all created equal. Interfering factors such as abnormal hematocrit, abnormal oxygen tension, and oxidizing/reducing substances can lead to inaccurate glucose measurements and result in inappropriate insulin dosing. The introduction of autocorrecting glucose meters has changed the POC testing landscape. Autocorrecting glucose meters provide more accurate measurements and have been associated with improved glycemic control in hospitalized patients. Continuous glucose monitoring has also created interest in using these platforms in at-risk inpatient populations. Future glucose monitoring technologies such as artificial intelligence/machine learning, wearable smart devices, and closed-loop insulin management systems are poised to transform glycemic management. The goal of this review is to provide an overview of glucose monitoring technology, summarize the clinical impact of glucose monitoring accuracy, and highlight emerging and future POC glucose monitoring technologies.

Co-transplantation with mesenchymal stem cells and endothelial cells improvise islet engraftment and survival in STZ treated hyperglycemic mice

Though intra-portal islet transplantation demonstrated as best suited strategy for the reversal of hyperglycemia without the threat of iatrogenic hyperglycemia in type 1 diabetes (T1D) in patients, the inferior quality of post-transplantation (tx) vascularization needs to be addressed for the maximization of post-tx islet survival. Therefore, in this study, we have first generated MSCs and endothelial progenitor cells (EPC) from mice bone marrow by in house optimized protocol and then 3-D co-cultured them with mice islets. Secretion of in the culture supernatant suggested the pro-angiogenic nature of 3D cultured mice islets. After 5 days post-tx of these pro-angiogenic islets in the omental pouch of syngeneic mice led to: 1) restoration of normoglycemia, 2) secretion of mouse C-peptide and 3) induction of angiogenic factors after 3 days of post-tx. The induction of angiogenic factors was done by RT-qPCR of omental biopsies. Importantly, pro-angiogenic islet recipient mice also demonstrated the clearance of glucose within 75 min, reflecting their efficient function and engraftment. Our results highlights needs of 3-D co-culture islets for superior quality post-tx islet vasculature and better engraftment â€" crux to improvise the challenges associated with post-tx islet vascularization and functions.

Applications of continuous glucose monitoring across settings and populations: Report from the 23rd Hong Kong diabetes and cardiovascular risk factors-East meets west symposium

Continuous glucose monitoring (CGM) is now an integral part of glycaemic management in people with type 1 diabetes and those with insulin-treated type 2 diabetes. Immediate access to information on CGM glucose levels and trends helps to inform food choices, titration and timing of insulin doses and prompts corrective actions in the event of impending hypo- or hyperglycaemia. Although glycated haemoglobin (HbA1c) remains an important measure of the average of glucose, CGM metrics including time-in-range (TIR) and other metrics on glycaemic variability and hypoglycaemia are strongly endorsed by people with diabetes as impacting their daily lives. There is growing consensus on definitions and targets of CGM metrics with an increasing number of studies demonstrating correlations between CGM metrics and incident complications of diabetes. Implementation of new technologies needs to take into consideration factors such as cost-effectiveness, accessibility as well as acceptability of the person with diabetes and healthcare professional. The United Kingdom is one of the few countries that have developed clinical pathways for integrating CGM into the routine care of people with type 1 diabetes. Besides type 1 diabetes, special groups such as people with impaired kidney function and women during pregnancy may derive additional benefits from CGM.

CuO/Cu/rGO nanocomposite anodic titania nanotubes for boosted non-enzymatic glucose biosensors

Highly arranged porous anodic titania (TiO2) nanotube arrays (ATNT) were fruitfully fabricated by the anodization of Ti foil in an ammonium fluoride electrolyte.

Predicting the response to SGLT-2 inhibitors as add-on therapy to multiple day injection insulin with glycated albumin: a pilot study

BACKGROUND

Achieving optimal glycemic targets is the main therapeutic goal in patients with type 2 diabetes (T2D) mellitus. HbA1c is the reference biomarker for monitoring glycemic control; however, in specific conditions affecting erythrocyte turnover or in patients on multiple daily injection (MDI) insulin regimens, the determination of glycated albumin (GA) may be preferable. Sodium-glucose cotransporter-2 (SGLT-2) inhibitors represent a novel class of antidiabetic drugs that lower plasma glucose concentrations quickly, with insulin-independent mechanisms. Herein, we explored the role of GA in predicting the short-term response to SGLT-2 inhibitors as add-on to MDI insulin.

METHODS

Sixteen patients with long-standing, poorly controlled T2D on MDI insulin starting an SGLT-2 inhibitor were subjected to plasma GA and HbA1c measurements at 30 days intervals for up to 3 months in order to examine the temporal changes of these glycemic biomarkers.

RESULTS

At the end of the study, grossly coincident with the life span of erythrocytes, a significant decrease in median HbA1c was observed, (from 8.7 [range: 8.2-9.3%] at baseline to 7.2 [range: 7.0-7.9%]), with the advantage of less insulin dose requirements. However, significant, and incremental reductions in median GA determinations could be already evident after 30 days (-3.5 [range: -7.5, -2.5%]) and 60 days (-6.4 [range: -10.5, -4.7%]) from the start of SGLT-2 inhibitor treatment and persisted for up to 3 months (-8.6 [range: -12.1, 6.1%]). The decrements of HbA1c observed at the 3-month visit were highly correlated with the concurrent absolute reductions of plasma GA (ρ=0.550, P=0.027), whereas a borderline significance could be demonstrated with reference to reductions in plasma GA at 30 and 60 days.

CONCLUSIONS

Although limited by the small number of participants, these preliminary findings suggest that GA, rather than HbA1c, could represent a useful and reliable biomarker in T2D to monitor the early glucose-lowering effects of antidiabetic drugs with rapid onset of action, such as SGLT-2 inhibitors and MDI insulin.

Quantification of glycated hemoglobin and glucose in vivo using Raman spectroscopy and artificial neural networks

Undiagnosed type 2 diabetes (T2D) remains a major public health concern. The global estimation of undiagnosed diabetes is about 46%, being this situation more critical in developing countries. Therefore, we proposed a non-invasive method to quantify glycated hemoglobin (HbA1c) and glucose in vivo. We developed a technique based on Raman spectroscopy, RReliefF as a feature selection method, and regression based on feed-forward artificial neural networks (FFNN). The spectra were obtained from the forearm, wrist, and index finger of 46 individuals. The use of FFNN allowed us to achieve an error in the predictive model of 0.69% for HbA1c and 30.12 mg/dL for glucose. Patients were classified according to HbA1c values into three categories: healthy, prediabetes, and T2D. The proposed method obtained a specificity and sensitivity of 87.50% and 80.77%, respectively. This work demonstrates the benefit of using artificial neural networks and feature selection techniques to enhance Raman spectra processing to determine glycated hemoglobin and glucose in patients with undiagnosed T2D.

Instrument-free single-step direct estimation of the plasma glucose level from one drop of blood using smartphone-interfaced analytics on a paper strip

We demonstrated an instrument-free miniaturized adaptation of the laboratory gold standard methodology for the direct estimation of plasma glucose from a drop of whole blood using a low-cost single-user-step paper-strip sensor interfaced with a smartphone. Unlike a majority of the existing glucose meters that use whole blood-based indirect sensing technologies, our direct adaptation of the gold-standard laboratory benchmark could eliminate the possibilities of cross interference with other analytes present in the whole blood by facilitating an in situ plasma separation, capillary flow and colorimetric reaction occurring concomitantly, without incurring additional device complexity or embodiment. The test reagents were dispensed in lyophilized form, and the resulting paper strips were found to be stable over three months stored in a normal freezer, rendering easy adaptability commensurate with the constrained supply chains in extreme resource-poor settings. Quantitative results could be arrived at via a completely-automated mobile-app-based image analytics interface developed using dynamic machine learning, obviating manual interpretation. The tests were demonstrated to be of high efficacy, even when executed by minimally trained frontline personnel having no special skill of drawing precise volume of blood, on deployment at under-resourced community centres having no in-built or accessible healthcare infrastructure. Clinical validation using 220 numbers of human blood samples in a double-blinded manner evidenced sensitivity and specificity of 98.11% and 96.7%, respectively, as compared to the results obtained from a laboratory-benchmarked biochemistry analyser, establishing its efficacy for public health and community disease management in resource-limited settings without any quality compromise of the test outcome.

A Mediated Enzymatic Electrochemical Sensor Using Paper-Based Laser-Induced Graphene

Laser-induced graphene (LIG) has been applied in many different sensing devices, from mechanical sensors to biochemical sensors. In particular, LIG fabricated on paper (PaperLIG) shows great promise for preparing cheap, flexible, and disposable biosensors. Distinct from the fabrication of LIG on polyimide, a two-step process is used for the fabrication of PaperLIG. In this study, firstly, a highly conductive PaperLIG is fabricated. Further characterization of PaperLIG confirmed that it was suitable for developing biosensors. Subsequently, the PaperLIG was used to construct a biosensor by immobilizing glucose oxidase, aminoferrocene, and Nafion on the surface. The developed glucose biosensor could be operated at a low applied potential (-90 mV) for amperometric measurements. The as-prepared biosensor demonstrated a limit of detection of (50-75 µM) and a linear range from 100 µM to 3 mM. The influence of the concentration of the Nafion casting solution on the performance of the developed biosensor was also investigated. Potential interfering species in saliva did not have a noticeable effect on the detection of glucose. Based on the experimental results, the simple-to-prepare PaperLIG-based saliva glucose biosensor shows great promise for application in future diabetes management.

Effect of hematocrit, galactose and ascorbic acid on the blood glucose readings of three point-of-care glucometers

Glucometers are commonly used in a variety of healthcare settings and use in critically ill patients should not be assumed without appropriate tool validation. The study objective was to evaluate the accuracy of three point-of-care glucometers (POCGs) to assess glucose concentration in human blood sample. The POCGs tested included three different instruments and utilized three factors (hematocrit [Hct], galactose and ascorbic acid) in glucose measurements to determine the glucometers' accuracy and compared to the reference laboratory biochemical analyzer (Cobs 8000, Roche, Basal, Switzerland). In this study, the Nova StatStrip glucometer showed no significant variation compared to the laboratory method at high glucose level with various Hct%. ACCU-Chek Inform II overestimated the glucose results at Hct 22% and underestimated at Hct 62%. The Freestyle glucometer showed lower glucose levels compared to the Cobas 8000 at Hct 62%. The ACCU-Check showed significant increase of blood glucose with low Hct% levels when compared to the laboratory method. The Freestyle showed a decreased level of glucose with high Hct 62% interference compared to the Cobas 8000. Galactose interference 100 and 200 mg/dL dramatically affected the accuracy of ACCU-Chek Inform II. Nevertheless, among all three POCGs in this study, the Nova StatStrip showed the most reliable and stable results for glucose level in the presence of interference. Especially, those in critical care units, whereas the Freestyle Precision Pro and ACCU-Chek Inform II were insufficiently accurate for critically ill patients.

Analytical validation of a portable human Accu-Chek glucometer in honeybee hemolymph

Glucose and trehalose are the main energy sources used by honeybees (Apis mellifera) for daily activities. However, there is no validated point-of-care method to reliably measure both sugars. We performed an analytical validation of a portable human glucometer (Accu-Chek; Roche) for glucose measurement in honeybee hemolymph compared to a reference method (GluCH, UniCel DxC 600; Beckman Coulter). We used 30 pooled hemolymph samples collected from the antennae of anesthetized honeybees and diluted 1:4 in 0.9% saline. We evaluated dilution linearity, spike recovery, and inter- and intra-assay imprecision. Glucose concentration was measured over time (2 h, 4 h, 8 h, 12 h, 1 d, 2 d, 3 d, 7 d, 21 d, 28 d) at various storage temperature (25°C, 4°C, -20°C, -80°C). The trehalose concentration was measured indirectly by trehalase hydrolyzation. Glucose concentrations measured by both instruments had a strong correlation (0.985, p < 0.0001) and a bias of -7.33 mmol/L (±1.96SD: 13.70 to -28.36), with linear agreement at <20 mmol/L (physiologic value: 100 mmol/L). The accuracy of the glucometer decreased at >20 mmol/L. Recovery of 115-130% of diluted spikes indicated good specificity. Inter- and intra-assay imprecision were 2.50% and 2.21%, respectively. Glucose concentrations fluctuated in stored samples dependent on time and temperature; however, glucose concentrations were constant with storage at -80°C for ≥28 d. The Accu-Chek glucometer is an adequate instrument to measure honeybee glucose concentration in hemolymph diluted with 0.9% NaCl, with good accuracy and precision at <20 mmol/L. Hemolymph storage at -80°C is suitable for long-term conservation of glucose.

The modern pharmacological approach to diabetes: innovative methods of monitoring and insulin treatment

INTRODUCTION

Diabetes mellitus, commonly known as just diabetes, is a group of metabolic disorders characterised by a high blood sugar level over a prolonged period of time. In order to maintain this blood glucose value in normal parameters, a careful monitoring of it and insulin administration are necessary.

AREAS COVERED

Thus, to facilitate this procedure, new blood glucose monitoring systems have been studied. The smart lens, the nano tattoo, non-invasive sensors based on reverse ionthophoresis and glucose oxidase - based continuous blood glucose monitoring systems, are the methods described in this study. Of course, not only is blood glucose monitoring important, but also the lifestyle of a drug or the way a drug is administered, especially in the cae of insulin. How insulin is administered is also a topic that we address in this article. In an attempt to promote compliance with the administration, we have discussed about new forms of administering insulin such as: oral, intranasal, administration on the oral mucosa and last but not least, transdermal administration.

EXPERT OPINION

Further, the attention of specialists should be directed to devices based on sensors, with a role in the interruption of insulin administration, in case of detection of hypoglycemia or the additional dose of insulin, if hyperglycemia is detected.

Recent Advances of Optical Sensors for Copper Ion Detection

A trace element copper (Cu²⁺) ion is the third most plentiful metal ion that necessary for all living organisms and playing a critical role in several processes. Nonetheless, according to cellular needs, deficient or excess Cu²⁺ ion cause various diseases. For all these reasons, optical sensors have been focused rapid Cu²⁺ ion detection in real-time with high selectivity and sensitivity. Optical sensors can measure fluorescence in the refractive index-adsorption from the relationships between light and matter. They have gained great attention in recent years due to the excellent advantages of simple and naked eye recognition, real-time detection, low cost, high specificity against analytes, a quick response, and the need for less complex equipment in analysis. This review aims to show the significance of Cu²⁺ ion detection and electively current trends in optical sensors. The integration of optical sensors with different systems, such as microfluidic systems, is mentioned, and their latest studies in medical and environmental applications also are depicted. Conclusions and future perspectives on these advances is added at the end of the review.

Comparison of point-of-care glucometers and laboratory based glucose oxidase test in determining blood glucose levels

INTRODUCTION

Alterations in blood glucose levels are common and an important determinant of a patient's admission outcomes, point-of-care glucometers, which are affected by a variety of factors, are increasingly used in clinical care. In this study we compared blood glucose levels determined by two commonly used glucometers (One Touch^® and Accu-check^®) with those of a standard laboratory method and determined the effect of haematocrit on glucose readings.

METHODS

Blood glucose levels were measured with One Touch^® and Accu-Check^® glucometers and the glucose oxidase method at the same time in 295 children aged 0 to 15 years over a 6-month period. Bland-Altman and correlation analysis were used to explore biases among the three methods. For all statistical tests, a p-value of less than 0.05 was considered statistically significant.

RESULTS

Most were males (51.2%) and the median (range) age was 1 year (1 day, 12 years). There was a significant correlation between each of the glucometer methods and laboratory blood sugar, and the correlation between the two glucometers was strong and significant. This correlation remained statistically significant even after controlling for haematocrit values. There was an acceptable level of bias (3.9 mg/dL) between the One Touch^® and Accu-check^® glucometers, but each had a remarkably large bias compared with the glucose oxidase method.

CONCLUSION

The use of a tested glucometer in clinical settings can aid in rapid decision-making, but there is a need to periodically cross-check with the glucose oxidase method in the laboratory to optimise treatment outcomes for children with dysglycaemia.

RuO2/rGO heterostructures as mimic peroxidases for colorimetric detection of glucose

The successful synthesis of ruthenium oxide/reduced graphene oxide (RuO₂/rGO) heterostructures by one-pot hydrothermal method using graphene oxides and RuCl₃ as precursors is reported. The heterostructures had high peroxidase-like (POD-like) activities, which catalyzes the oxidation of classical peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H₂O₂ to create a blue colored reaction product. The catalytic activity was significantly enhanced by the synergistic effect between RuO₂ nanoparticles and rGO. RuO₂/rGO had a low K_m of 0.068 mM and a high v_max of 1.228 × 10^-7 M·s^-1 towards TMB in the TMB-H₂O₂ catalytic oxidation system. In addition, the POD-like activity originating from the electron transfer mechanism was confirmed by cytochrome C (Cyt C) oxidation experiment. A colorimetric method based on RuO₂/rGO heterostructures was developed with good sensitivity and selectivity for glucose detection with a limit of detection of 3.34 μM and a linear range of 0-1500 μM. The RuO₂/rGO heterostructures have potential applications in the biomedical areas, such as biosensor and diagnostics.

A machine learning-based on-demand sweat glucose reporting platform

Diabetes is a chronic endocrine disease that occurs due to an imbalance in glucose levels and altering carbohydrate metabolism. It is a leading cause of morbidity, resulting in a reduced quality of life even in developed societies, primarily affected by a sedentary lifestyle and often leading to mortality. Keeping track of blood glucose levels noninvasively has been made possible due to diverse breakthroughs in wearable sensor technology coupled with holistic digital healthcare. Efficient glucose management has been revolutionized by the development of continuous glucose monitoring sensors and wearable, non/minimally invasive devices that measure glucose concentration by exploiting different physical principles, e.g., glucose oxidase, fluorescence, or skin dielectric properties, and provide real-time measurements every 1-5 min. This paper presents a highly novel and completely non-invasive sweat sensor platform technology that can measure and report glucose concentrations from passively expressed human eccrine sweat using electrochemical impedance spectroscopy and affinity capture probe functionalized sensor surfaces. The sensor samples 1-5 µL of sweat from the wearer every 1-5 min and reports sweat glucose from a machine learning algorithm that samples the analytical reference values from the electrochemical sweat sensor. These values are then converted to continuous time-varying signals using the interpolation methodology. Supervised machine learning, the decision tree regression algorithm, shows the goodness of fit R² of 0.94 was achieved with an RMSE value of 0.1 mg/dL. The output of the model was tested on three human subject datasets. The results were able to capture the glucose progression trend correctly. Sweet sensor platform technology demonstrates a dynamic response over the physiological sweat glucose range of 1-4 mg/dL measured from 3 human subjects. The technology described in the manuscript shows promise for real-time biomarkers such as glucose reporting from passively expressed human eccrine sweat.

Glucose biosensors in clinical practice: principles, limits and perspectives of currently used devices

The demand of glucose monitoring devices and even of updated guidelines for the management of diabetic patients is dramatically increasing due to the progressive rise in the prevalence of diabetes mellitus and the need to prevent its complications. Even though the introduction of the first glucose sensor occurred decades ago, important advances both from the technological and clinical point of view have contributed to a substantial improvement in quality healthcare. This review aims to bring together purely technological and clinical aspects of interest in the field of glucose devices by proposing a roadmap in glucose monitoring and management of patients with diabetes. Also, it prospects other biological fluids to be examined as further options in diabetes care, and suggests, throughout the technology innovation process, future directions to improve the follow-up, treatment, and clinical outcomes of patients.

Glycaemic control and novel technology management strategies in pregestational diabetes mellitus

INTRODUCTION

Pregestational diabetes (PGDM) is an increasingly common and complex condition that infers risk to both mother and infant. To prevent serious morbidity, strict glycaemic control is essential. The aim of this review is to review the glucose sensing and insulin delivering technologies currently available for women with PGDM.

METHODS

We reviewed online databases for articles relating to technology use in pregnancy using a combination of keywords and MeSH headings. Relevant articles are included below.

RESULTS

A number of technological advancements have improved care and outcomes for women with PGDM. Real time continuous glucose monitoring (rtCGM) offers clear advantages in terms of infants size and neonatal intensive care unit admissions; and further benefits are seen when combined with continuous subcutaneous insulin delivery (insulin pump) and algorithms which continuously adjust insulin levels to glucose targets (hybrid closed loop). Other advancements including flash or intermittent scanning CGM (isCGM) and stand-alone insulin pumps do not confer as many advantages for women and their infants, however they are increasingly used outside of pregnancy and many women enter pregnancy already using these devices.

DISCUSSION

This article offers a discussion of the most commonly used technologies in pregnancy and evaluates their current and future roles.

Use of Continuous Glucose Monitoring in the Assessment and Management of Patients With Diabetes and Chronic Kidney Disease

In developed countries, diabetes is the leading cause of chronic kidney disease (CKD) and accounts for 50% of incidence of end stage kidney disease. Despite declining prevalence of micro- and macrovascular complications, there are rising trends in renal replacement therapy in diabetes. Optimal glycemic control may reduce risk of progression of CKD and related death. However, assessing glycemic control in patients with advanced CKD and on dialysis (G4-5) can be challenging. Laboratory biomarkers, such as glycated haemoglobin (HbA_1c), may be biased by abnormalities in blood haemoglobin, use of iron therapy and erythropoiesis-stimulating agents and chronic inflammation due to uraemia. Similarly, glycated albumin and fructosamine may be biased by abnormal protein turnover. Patients with advanced CKD exhibited heterogeneity in glycemic control ranging from severe insulin resistance to 'burnt-out' beta-cell function. They also had high risk of hypoglycaemia due to reduced renal gluconeogenesis, frequent use of insulin and dysregulation of counterregulatory hormones. Continuous glucose monitoring (CGM) systems measure glucose in interstitial fluid every few minutes and provide an alternative and more reliable method of glycemic assessment, including asymptomatic hypoglycaemia and hyperglycaemic excursions. Recent international guidelines recommended use of CGM-derived Glucose Management Index (GMI) in patients with advanced CKD although data are scarce in this population. Using CGM, patients with CKD were found to experience marked glycemic fluctuations with hypoglycemia due to loss of glucose and insulin during haemodialysis (HD) followed by hyperglycemia in the post-HD period. On the other hand, during peritoneal dialysis, patients may experience glycemic excursions with influx of glucose from dialysate solutions. These undesirable glucose exposure and variability may accelerate decline of residual renal function. Although CGM may improve the quality of glycemic monitoring and control in populations with CKD, further studies are needed to confirm the accuracy, optimal mode and frequency of CGM as well as their cost-effectiveness and user-acceptability in patients with advanced CKD and dialysis.

Non-invasive electrochemistry-driven metals tracing in human biofluids

Wearable analytical devices represent the future for fast, de-centralized, and human-centered health monitoring. Electrochemistry-based platforms have been highlighted as the role model for future developments amid diverse strategies and transduction technologies. Among the various relevant analytes to be real-time and non-invasively monitored in bodily fluids, we review the latest wearable achievements towards determining essential and toxic metals. On-skin measurements represent an excellent possibility for humankind: real-time monitoring, digital/fast communication with specialists, quick interventions, removing barriers in developing countries. In this review, we discuss the achievements over the last 5 years in non-invasive electrochemical platforms, providing a comprehensive table for quick visualizing the diverse sensing/technological advances. In the final section, challenges and future perspectives about wearables are deeply discussed.

Fluorescent Sensor Array for Quantitative Determination of Saccharides

Accurate monitoring of sugar levels is essential for many fields from food industry to human health. Here, we developed FRET-based dual chromophore sensors for saccharides that form oxazolidine boronate and may be employed as a noninvasive method for monitoring of sugar levels in biological fluids, namely, urine. The saccharide-binding properties of the sensors were studied using fluorescence spectroscopy and utilized in the determination of saccharides in a high-throughput manner. Here, two fluorescent sensors were successful in the classification of nine different monosaccharides and disaccharides with 100% correct classification. Furthermore, the dual chromophore self-assembled sensors were successfully utilized for the quantitative determination of important carbohydrates such as glucose in the presence of competitive saccharides (fructose) and in complex media (urine) without sample pretreatment. The present fluorescent sensors allow for quantification of glucose in a concentration range of 0-60 mM, which matches the concentration range of frequently used urinalysis test strips.

A semiparametric Gumbel regression model for analyzing longitudinal data with non-normal tails

Abnormal longitudinal values in biomarkers can be a sign of abnormal status or signal development of a disease. Identifying new biomarkers for early and efficient disease detection is crucial for disease prevention. Compared to the majority of the healthy general population, abnormal values are located within the tails of the biomarker distribution. Thus, parametric regression models that accommodate abnormal values in biomarkers can better detect the association between biomarkers and disease. In this article, we propose semiparametric Gumbel regression models for (1) longitudinal continuous biomarker outcomes, (2) flexibly modeling the time-effect on the outcome, and (3) accounting for the measurement error in biomarker measurements. We adopted the EM algorithm in combination with a two-dimensional grid search to estimate regression parameters and a function of time-effect. We proposed an efficient asymptotic variance estimator for regression parameter estimates. The proposed estimator is asymptotically unbiased in both theory and simulation studies. We applied the proposed model and two other models to investigate associations between fasting blood glucose biomarkers and potential risk factors from a diabetes ancillary study to the Atherosclerosis Risk in Communities (ARIC) study. The real data application was illustrated by fitting the proposed regression model and graphically evaluating the goodness-of-fit value.

Blood glucose concentration is unchanged during exposure to acute normobaric hypoxia in healthy humans

Normal blood [glucose] regulation is critical to support metabolism, particularly in contexts of metabolic stressors (e.g., exercise, high altitude hypoxia). Data regarding blood [glucose] regulation in hypoxia are inconclusive. We aimed to characterize blood [glucose] over 80 min following glucose ingestion during both normoxia and acute normobaric hypoxia. In a randomized cross-over design, on two separate days, 28 healthy participants (16 females; 21.8 ± 1.6 years; BMI 22.8 ± 2.5 kg/m2 ) were randomly exposed to either NX (room air; fraction of inspired [FI ]O2 ~0.21) or HX (FI O2 ~0.148) in a normobaric hypoxia chamber. Measured FI O2 and peripheral oxygen saturation were both lower at baseline in hypoxia (p < 0.001), which was maintained over 80 min, confirming the hypoxic intervention. Following a 10-min baseline (BL) under both conditions, participants consumed a standardized glucose beverage (75 g, 296 ml) and blood [glucose] and physiological variables were measured at BL intermittently over 80 min. Blood [glucose] was measured from finger capillary samples via glucometer. Initial fasted blood [glucose] was not different between trials (NX:4.8 ± 0.4 vs. HX:4.9 ± 0.4 mmol/L; p = 0.47). Blood [glucose] was sampled every 10 min (absolute, delta, and percent change) following glucose ingestion over 80 min, and was not different between conditions (p > 0.77). In addition, mean, peak, and time-to-peak responses during the 80 min were not different between conditions (p > 0.14). There were also no sex differences in these blood [glucose] responses in hypoxia. We conclude that glucose regulation is unchanged in young, healthy participants with exposure to acute steady-state normobaric hypoxia, likely due to counterbalancing mechanisms underlying blood [glucose] regulation in hypoxia.

Development of DNA Biosensors Based on DNAzymes and Nucleases

DNA biosensors play important roles in environmental, medical, industrial and agricultural analysis. Many DNA biosensors have been designed based on the enzyme catalytic reaction. Because of the importance of enzymes in biosensors, we present a review on this topic. In this review, the enzymes were divided into DNAzymes and nucleases according to their chemical nature. Firstly, we introduced the DNAzymes with different function inducing cleavage, metalation, peroxidase, ligation and allosterism. In this section, the G-quadruplex DNAzyme, as a hot topic in recent years, was described in detail. Then, the nucleases-assisted signal amplification method was also reviewed in three categories including exonucleases, endonucleases and other nucleases according to the digestion sites in DNA substrates. In exonucleases section, the Exo I and Exo III were selected as examples. Then, the DNase I, BamH I, nicking endonuclease, S1 nuclease, the duplex specific nuclease (DSN) and RNases were chosen to illustrate the application of endonucleases. In other nucleases section, DNA polymerases and DNA ligases were detailed. Last, the challenges and future perspectives in the field were discussed.

A Multicenter Evaluation of a Point-of-Care Blood Glucose Meter System in Critically Ill Patients

BACKGROUND

Our purpose was to evaluate the performance of the ACCU-CHEK® Inform II blood glucose monitoring system (Roche Diagnostics GmbH) compared with the perchloric acid hexokinase (PCA-HK) comparator method on the cobas® 6000 analyzer (Roche Diagnostics International Ltd) in critically ill patients.

METHODS

Overall, 476 arterial (376 pediatric/adult, 100 neonate), 375 venous, and 100 neonatal heel-stick whole-blood samples were collected and evaluated from critical care settings at 10 US hospitals, including the emergency department, medical and surgical intensive care units (ICUs), and neonatal and pediatric ICUs. The ACCU-CHEK Inform II system was evaluated at 2 cutoff boundaries: boundary 1 was ≥95% of results within ±12 mg/dL of the reference (samples with blood glucose <75 mg/dL) or ±12% of the reference (glucose ≥75 mg/dL), and boundary 2 was ≥98% of results within ±15 mg/dL or ±15% of the reference. Clinical performance was assessed by evaluating sample data using Parkes error grid, Monte Carlo simulation, and sensitivity and specificity analyses to estimate clinical accuracy and implications for insulin dosing when using the ACCU-CHEK Inform II system.

RESULTS

Proportions of results within evaluation boundaries 1 and 2, respectively, were 96% and 98% for venous samples, 94% and 97% for pediatric and adult arterial samples, 84% and 98% for neonatal arterial samples, and 96% and 100% for neonatal heel-stick samples. Clinical evaluation demonstrated high specificity and sensitivity, with low risk of potential insulin-dosing errors.

CONCLUSIONS

The ACCU-CHEK Inform II system demonstrated clinically acceptable performance against the PCA-HK reference method for blood glucose monitoring in a diverse population of critically ill patients in US care settings.

Challenge of diabetes mellitus and researchers’ contributions to its control

The aim of this review study was to assess the past significant events on diabetes mellitus, transformations that took place over the years in the medical records of treatment, countries involved, and the researchers who brought about the revolutions. This study used the content analysis to report the existence of diabetes mellitus and the treatments provided by researchers to control it. The focus was mainly on three main types of diabetes (type 1, type 2, and type 3 diabetes). Ethical consideration has also helped to boost diabetic studies globally. The research has a history path from pharmaceuticals of organic-based drugs to metal-based drugs with their nanoparticles in addition to the impacts of nanomedicine, biosensors, and telemedicine. Ongoing and future studies in alternative medicine such as vanadium nanoparticles (metal nanoparticles) are promising.

Clarke Error Grid Analysis for Performance Evaluation of Glucometers in a Tertiary Care Referral Hospital

Glucometer is the most commonly used POCT device and guides monitoring of blood glucose level in both clinical settings and outside. Inaccurate glucometer readings resulting in erroneous therapeutic intervention has critical consequences on patient care. Regulatory guidelines for performance evaluation of glucometers are not available in many countries. A robust program implemented by the hospital is essential to ensure accuracy and precision of glucometers to produce optimal results. The objective of this study was to design a quality assurance program for the evaluation of glucometers in a high volume tertiary care referral hospital and evaluate the results from July'18 to July'19. Seventy three glucometers used across the hospital were subjected to Internal Quality Control checks and Proficiency Testing performed once a month and every 3 months respectively. The results were reviewed and plotted on a Bland Altman Graph. Clarke Error Grid Analysis was done to evaluate the clinical significance of inaccuracies in the measurement of blood glucose concentration as per ISO 15197: 2013. Eight devices were identified as unacceptable by ISO standards and replaced subsequently. 96.83% and 3.17% of the values were in Zone A and B of Clarke Error Grid Analysis. The study complied with the standard which requires that 99% of the values fall within zones A and B. The review of the program after one year and its ability to identify defective glucometers has validated the efficacy of the model. The method used may be suggested as a prototype for quality management of glucometers in a clinical setting.

What We Should Consider in Point of Care Blood Glucose Test; Current Quality Management Status of a Single Institution

Background and Objectives: Point of care test (POCT) is generally performed by non-laboratory staff who often lack an understanding on the quality control and quality assurance programs. The purpose of this study was to understand the current status of quality management of point of care (POC) blood glucose testing in a single institution where non-laboratory staff perform the tests. Materials and Methods: From July to August 2020, management status of glucometer, test strips, quality control (QC) materials, quality assurance program, and operators’ response to processing of displayed results was monitored in all Soonchunhyang University Bucheon hospital departments that performed POC blood glucose test. Results of the POC blood glucose test conducted from January 2019 to May 2020 were analyzed retrospectively. Results: A total 124 glucometers were monitored in 47 departments. Insufficient management of approximately 50% of blood sugar, test strips, and QC materials was observed. Although daily QC was conducted by 95.7% of the departments, the QC records were inaccurate. The method of recording test results varied with departments and operators. Various judgments and troubleshooting were performed on the unexpected or out of measurable range results, including some inappropriate processes. In POC blood glucose test results review, 4568 atypical results were identified from a total of 572,207 results. Conclusions: Sufficient training of the non-laboratory staff and ongoing assessment of competency through recertification is needed to maintain acceptable levels of POCT quality. In this study, various problems were identified in glucometer and reagent management, QC and post-analytic phase. We believe that these results provide meaningful basal information for planning effective operators’ training and competency evaluation, and the development of an efficient POCT quality management system.