Accuracy Of Glucose Measurements Research Articles

Nonenzymatic Glucose Sensor Using Bimetallic Catalysts.

Bimetallic glucose oxidation electrocatalysts were synthesized by two electrochemical reduction reactions carried out in series onto a titanium electrode. Nickel was deposited in the first synthesis stage followed by either silver or copper in the second stage to form Ag@Ni and Cu@Ni bimetallic structures. The chemical composition, crystal structure, and morphology of the resulting metal coating of the titanium electrode were investigated by X-ray diffraction, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and electron microscopy. The electrocatalytic performance of the coated titanium electrodes toward glucose oxidation was probed using cyclic voltammetry and amperometry. It was found that the unique high surface area bimetallic structures have superior electrocatalytic activity compared to nickel alone. The resulting catalyst-coated titanium electrode served as a nonenzymatic glucose sensor with high sensitivity and low limit of detection for glucose. The Cu@Ni catalyst enables accurate measurement of glucose over the concentration range of 0.2-12 mM, which includes the full normal human blood glucose range, with the maximum level extending high enough to encompass warning levels for prediabetic and diabetic conditions. The sensors were also found to perform well in the presence of several chemical compounds found in human blood known to interfere with nonenzymatic sensors.

Development of mobile biosensor reader for wearable sweat glucose biosensor application

Sweat contains numerous biomarkers, including glucose, which can provide valuable insights into an individual’s metabolic state. Noninvasive glucose monitoring eliminates the need for frequent finger pricks or blood samples, offering greater convenience and reducing discomfort for individuals with diabetes. These biosensors are designed to detect and quantify glucose levels through various sensing mechanisms, such as enzymatic reactions or electrochemical measurements. The integration of biosensors into wearable devices, such as smartwatches, patches, or flexible electronics, allows for mobile glucose monitoring in sweat. Accurate glucose measurements require calibration and validation against reference measurements, such as blood glucose levels. Research focuses on developing calibration algorithms and improving the accuracy and reliability of mobile glucose biosensors in sweat.

Smartphone-Based Chemiluminescence Glucose Biosensor Employing a Peroxidase-Mimicking, Guanosine-Based Self-Assembled Hydrogel

Chemiluminescence is widely used for hydrogen peroxide detection, mainly exploiting the highly sensitive peroxidase-luminol-H2O2 system. Hydrogen peroxide plays an important role in several physiological and pathological processes and is produced by oxidases, thus providing a straightforward way to quantify these enzymes and their substrates. Recently, biomolecular self-assembled materials obtained by guanosine and its derivatives and displaying peroxidase enzyme-like catalytic activity have received great interest for hydrogen peroxide biosensing. These soft materials are highly biocompatible and can incorporate foreign substances while preserving a benign environment for biosensing events. In this work, a self-assembled guanosine-derived hydrogel containing a chemiluminescent reagent (luminol) and a catalytic cofactor (hemin) was used as a H2O2-responsive material displaying peroxidase-like activity. Once loaded with glucose oxidase, the hydrogel provided increased enzyme stability and catalytic activity even in alkaline and oxidizing conditions. By exploiting 3D printing technology, a smartphone-based portable chemiluminescence biosensor for glucose was developed. The biosensor allowed the accurate measurement of glucose in serum, including both hypo- and hyperglycemic samples, with a limit of detection of 120 µmol L−1. This approach could be applied for other oxidases, thus enabling the development of bioassays to quantify biomarkers of clinical interest at the point of care.

KADAR GLUKOSA PADA SERUM LIPEMIK DENGAN PENGGUNAAN POLYETHYLENE GLYCOL 6000 8% DAN HIGH SPEED SENTRIFUGASI

Bacground: Lipemic serum is a problem in many laboratories because it can cause the results of glucose levels in the serum to be falsely high. The examination uses a photometric method, which can cause interference with wave lengths and light scattering. As an alternative to high-speed centrifugation to remove lipemic serum, another method for handling lipemic serum is precipitation, which is carried out by processing polyethylene glycol 6000 8%.Aims: This research wants to know the differences in the handling of lipemic serum before and after being processed using polyethlyene glycol 6000 8% and high-speed centrifugation.Method: This type of research is an experiment with Static Group Comparison. Research conducted at the Clinical Pathology Laboratory Installation at the Gadjah Mada University Academic Hospital in November 2022. The sample of this study was lipemic serum with a total of twenty samples obtained from the rest of the examination in two Clinical Laboratory Installations Hospitals in Yogyakarta. Research data were analyzed using the Paired T-Test and Independent T-Test. Result: The statistical analysis (p = 0.000) 0.05 revealed that there is a difference in lipemic serum glucose levels before and after PEG 6000 8% processing and high-speed centrifugation. Before processing with polyethylene glycol 6000 8% and high-speed centrifugation, the average yield of glucose levels in lipemic serum was 116.3 mg/dl. The average glucose level before and after PEG 6000 8% processing was 108.65 mg/dl. Before and after high-speed centrifugation, the average glucose level was 114.1 mg/dl.Conclusion: Overall, both the PEG 6000 8% processing and the high-speed centrifugation resulted in a significant decrease in lipemic serum glucose levels. These methods appear to be effective in reducing the interference caused by lipemia and improving the accuracy of glucose measurements in the serum.

Evaluating the Clinical Accuracy of a Non-invasive Single-Fasting-Calibration Glucometer in Patients with Diabetes: A Multicentre Study.

The aim of this study was to evaluate the stability and accuracy of glucose measurements determined using the metabolic heat conformation (MHC)-based non-invasive glucometer in a multicentre, self-controlled clinical trial. This device is the first to obtain a medical device registration certificate awarded by the National Medical Products Administration of China (NMPA). The multicentre clinical study was conducted at three sites and enrolled 200 subjects whose glucose was measured with a non-invasive glucometer (the Contour Plus blood glucose monitoring system) and by venous plasma glucose (VPG) measurements, in a fasted state and at 2 and 4h after meals. Based on both the non-invasive and VPG measurements, 93.9% (95% confidence interval 91.7-95.6%) of the blood glucose (BG) values fell within consensus error grid (CEG) zones A + B. The measurements obtained in a fasted state and at 2h after meals were more accurate, with 99.0% and 97.0% of the BG values, respectively, falling within zones A + B. Compared to those subjects who received insulin, the proportion of values in zones A + B and the correlation coefficients were 3.1% and 0.0596 higher, respectively. The accuracy of the non-invasive glucometer was influenced by the level of insulin resistance calculated by the homeostatic model assessment method, which had a correlation coefficient with the mean absolute relative difference of - 0.1588 (P = 0.0001). The MHC-based non-invasive glucometer assessed in the present study demonstrates generally high stability and accuracy in the glucose monitoring of people with diabetes. The calculation model needs to be further explored and optimised for patients with different diabetes subtypes, levels of insulin resistance and insulin secretion capacity. ChiCTR1900020523.

Non-invasive blood glucose sensing by machine learning of optic fiber-based speckle pattern variation.

.SignificanceThe ability to perform frequent non-invasive monitoring of glucose in the bloodstream is very applicable for diabetic patients.AimWe experimentally verified a non-invasive multimode fiber-based technique for sensing glucose concentration in the bloodstream by extracting and analyzing the collected speckle patterns.ApproachThe proposed sensor consists of a laser source, digital camera, computer, multimode fiber, and alternating current (AC) generated magnetic field source. The experiments were performed using a covered (with cladding and jacket) and uncovered (without cladding and jacket) multimode fiber touching the skin under a magnetic field and without it. The subject’s finger was placed on a fiber to detect the glucose concentration. The method tracks variations in the speckle patterns due to light interaction with the bloodstream affected by blood glucose.ResultsThe uncovered fiber placed above the finger under the AC magnetic field (150 G) at 140 Hz was found to have a lock-in amplification role, improving the glucose detection precision. The application of the machine learning algorithms in preprocessed speckle pattern data increase glucose measurement accuracy. Classification of the speckle patterns for uncovered fiber under the AC magnetic field allowed for detection of the blood glucose with high accuracy for all tested subjects compared with other tested configurations.ConclusionsThe proposed technique was theoretically analyzed and experimentally validated in this work. The results were verified by the traditional finger-prick method, which was also used for classification as a conventional reference marker of blood glucose levels. The main goal of the proposed technique was to develop a non-invasive, low-cost blood glucose sensor for easy use by humans.

Development, validation and application of a GC-MS method for quantification of glucose and lactate in vitreous humor

Develop and apply a GC-MS method for quantifying glucose and lactate in vitreous humor. In routine forensic toxicological screening, glucose and lactate are measured in vitreous humor to evaluate the ante-mortem glycaemic status and to identify possible lactate acidosis. Concentrations for both endogenous compounds are required in the assessment of hypo-, normo- or hyperglycaemic status before death. In our laboratory, no in-house chromatographic method was available and diluted vitreous humor samples had to be analysed by an external laboratory, using a spectrophotometric method validated for serum. Starting from a GC-MS method available for GHB and BHB, we investigated the simultaneous measurement of glucose and lactate to increase sample throughput. An analytical method was developed for analysis of glucose and lactate, based on an available GC-MS method used in-house for other analytes and on literature (Shojaee-Moradie et al., Journal of Mass Spectrometry 1996;31:961–966), employing a combination of two derivatisation reactions. Glucose required both oxime and trimethylsilyl derivatisation to achieve compatibility with GC-MS. For lactate, only the silylation step was necessary. Method validation was carried out using in-house prepared quality control samples. Authentic vitreous humor samples ( n = 100) were analysed in parallel between October 2021 and April 2022, comparing the results of the newly developed method to those from the external laboratory. The derivatisation time and calibration model were optimised. The method was validated according to the guideline on bioanalytical method validation provided by the European Medicines Agency. Linear calibration curves showed R 2 > 0.99 for glucose and lactate and the lower limit of quantification (LLOQ) was 12.5 mg/dL for both compounds. Spearman's ρ showed a strong, statistically significant correlation between the results obtained by the two labs ( P < 0.001; 0.836 for lactate, 0.963 for glucose). Bland–Altman plots were used to assess agreement between the measurements. For glucose, 11% of the analysed samples fell out of the 95% confidence interval; for lactate, only 9%. Deviant samples were re-analysed with the new method, yielding the same results, suggesting the possibility of deviant results by the spectrophotometric method. For lactate, the results of the developed method tended to show a small positive bias compared to those of the clinical lab. The established LLOQ was well below the postmortem cut-off values for determining hypoglycaemia and the measured glucose and lactate concentrations in most authentic samples. Results for the authentic samples showed good agreement between both methods and for both analytes. The developed and validated GC-MS based method has shown to be suitable for accurate measurement of glucose and lactate concentrations in vitreous humor.

Improved Accuracy of Tissue Glucose Measurement Using Low Magnification Optical Coherence Tomography

Optical coherence tomography (OCT) has a comparatively high spatial resolution among tomographic bioimaging techniques and is less affected by changes in physiological conditions such as temperature, blood pressure, and osmolytes in the tissue. OCT detects changes in the refractive index of tissues, which is a function of the tissue glucose concentration (TGC). OCT signal intensity generally decreases with tissue depth, and its slope is expected to show a negative correlation with TGC in the interstitial fluid, reflecting blood glucose concentration (BGC). The currently applied OCT system for measuring TGC does not satisfy the accuracy for clinical demand, mainly because of the temporal and spatial variations of living tissues. In this paper, we propose a low magnification OCT (LM-OCT) for noninvasive monitoring of TGC by reducing the spatial resolution and show that LM-OCT significantly improves the accuracy of glucose measurement. The continuous development of LM-OCT in this direction is expected to offer a reliable and noninvasive tool for the clinical monitoring of TGC.

Laser-induced graphene non-enzymatic glucose sensors for on-body measurements

Non-enzymatic glucose sensors outperform enzymatic ones in terms of cost, sensitivity, stability, and operating duration. Though highly sensitive, it is still desirable to further improve the sensitivity of non-enzymatic glucose sensors to detect a trace amount of glucose in sweat and other biofluids. Among the demonstrated effective approaches using bimetals or 3D porous structures, the porous laser-induced graphene (LIG) on flexible polymers showcases good conductivity and a simple fabrication process for the integration of sensing materials. The uniform electroless plating of the nickel and gold layer on LIG electrodes demonstrates significantly enhanced sensitivity and a large linear range for glucose sensing. The sensor with the porous LIG foam exhibits a high sensitivity of 1080 μA mM−1 cm−2, whereas a further increased sensitivity of 3500 μA mM−1 cm−2 is obtained with LIG fibers (LIGF). Impressively, a large linear range (0–30 mM) can be achieved by changing the bias voltage from 0.5 to 0.1 V due to the Au coating. Because the existing non-enzymatic glucose sensors are limited to use in basic solutions, their application in wearable electronics is elusive. In addition to the reduced requirement for the basic solution, this work integrates a porous encapsulating reaction cavity containing alkali solutions with a soft, skin-interfaced microfluidic component to provide integrated microfluidic non-enzymatic glucose sensors for sweat sampling and glucose sensing. The accurate glucose measurements from the human sweat and cell culture media showcase the practical utility, which opens up opportunities for the non-enzymatic glucose sensors in wearable electronics.

Accuracy of Blood Glucose Measurement and Blood Glucose Targets.

To summarize new evidence regarding the methodological aspects of blood glucose control in the intensive care unit (ICU). We reviewed the literature on blood glucose control in the ICU up to August 2019 through Ovid Medline and Pubmed. Since the publication of the Leuven studies, the benefits of glycemic control have been recognized. However, the methodology of blood glucose control, notably the blood glucose measurement accuracy and the insulin titration protocol, plays an important but underestimated role. This may partially explain the negative results of the large, pragmatic multicenter trials and made everyone realize that tight glycemic control with less-frequent glucose measurements on less accurate blood glucose meters is neither feasible nor advisable in daily practice. Blood gas analyzers remain the gold standard. New generation point-of-care blood glucose meters may be an alternative when using whole blood of critically ill patients in combination with a clinically validated insulin dosing algorithm. When implementing blood glucose management in an ICU one needs to take into account the interaction between aimed glycemic target and blood glucose measurement methodology.

Reduced Graphene Oxide/Pt Nanoparticles/Zn‐MOF‐74 Nanomaterial for a Glucose Biosensor Construction

AbstractIn this study, a new glucose biosensor was fabricated by immobilizing glucose oxidase (GOx) on platinum nanoparticles (Pt NPs) decorated reduced graphene oxide (rGO)/Zn‐MOF‐74 hybrid nanomaterial. Herein, the biosensor fused the advantages of rGO with those of porous Zn‐MOF and conductive Pt NPs. This has not only enlarged the surface area and porosity for the efficient GOx immobilization and faster mass transport, but also provided favorable electrochemical features such as high current density, remarkable electron mobility through metal nanoparticles, and improved electron transfer between the components. The GOx‐rGO/Pt NPs@Zn‐MOF‐74 coated electrode displayed a linear measurement range for glucose from 0.006 to 6 mM, with a detection limit of 1.8 μM (S/N: 3) and sensitivity of 64.51 μA mM−1 cm−2. The amperometric response of the enzyme biosensor demonstrated the typical behavior of Michaelis‐Menten kinetics. The obtained satisfying sensitivity and measurement range enabled fast and accurate glucose measurement in cherry juice using the fabricated biosensor. The water‐stable Zn‐MOF‐74 demonstrated higher enzyme loading capacity and can be potent supporting material for biosensor construction.

Design of Electrodes on Gold Test Strips for Enhanced Accuracy in Glucose Measurement

This paper reviews the practical process of designing the electrodes on electroless immersion gold-plated test strips for glucose measurement. We have found that great care must be taken on determining the width and length of the working and reference electrodes, to yield the optimum performance on electroless immersion gold-plated glucose test strips for glucose measurement. Preferably, a width of at least 0.6 mm and a length of at least 24 mm are recommended to prevent variance in electrode resistance during mass production of electroless immersion gold-plated glucose test strips, in order to enhance the accuracy of glucose measurement. This paper also recommended that, if two different geometric sizes of test strips are going to be used on the same glucose meter, both test strips must use different lengths and widths on the working and reference electrodes to yield the same electrical resistance and hence similar electrochemical performance.

Glucose control in the ICU.

Critically ill patients usually develop hyperglycemia, which is associated with adverse outcome. Controversy exists whether the relationship is causal or not. This review summarizes recent evidence regarding glucose control in the ICU. Despite promising effects of tight glucose control in pioneer randomized controlled trials, the benefit has not been confirmed in subsequent multicenter studies and one trial found potential harm. This discrepancy could be explained by methodological differences between the trials rather than by a different case mix. Strategies to improve the efficacy and safety of tight glucose control have been developed, including the use of computerized treatment algorithms. The ideal blood glucose target remains unclear and may depend on the context. As compared with tolerating severe hyperglycemia, tight glucose control is well tolerated and effective in patients receiving early parenteral nutrition when provided with a protocol that includes frequent, accurate glucose measurements and avoids large glucose fluctuations. All patient subgroups potentially benefit, with the possible exception of patients with poorly controlled diabetes, who may need less aggressive glucose control. It remains unclear whether tight glucose control is beneficial or not in the absence of early parenteral nutrition.

Analysis of "Performance of a Factory-Calibrated, Real-Time Continuous Glucose Monitoring System in Pediatric Participants With Type 1 Diabetes".

Accuracy of sensors play an important role in the acceptance and long-term use of CGM which is related to improved glycemic outcome. This has been lower in children and adolescents in the past for reasons such as size of the device, pain, and necessity to calibrate sensors but also inaccuracy and perceived nonreliability on alarms among others. In the study of Welsh et al, performance of a new, factory-calibrated sensor was assessed. The accuracy of the sensor, as measured in MARD, paired values within 20/20% or 15/15% and surveillance error grid analysis showed very good results, although less so in low value range <70 mg/dL, falling rate of change, and on first day of use. Accurate glucose measurements especially in these incidences are of utmost importance to people with diabetes as their treatment decisions are based on these, also in the beginning of sensor use.

Transmission Spectroscopy in Noninvasive Blood Glucose Measurement

The use of laser diodes and photodiodes in transmission spectroscopy has some effects (temperature, time, spectral, and spatial) reducing the accuracy of glucose measurement. These effects can be reduced by using a (1600 ± 3) nm laser in combination with fixation and occlusion of the tissue area under examination. In this work, a method is suggested that allows spatial displacements of the system to be taken into account. A number of methods for reducing the effect of the thermal drift of the diodes are also suggested. A portable noninvasive optical glucose meter implemented using these methods provides high clinical performance: more than 97% of the measurements are in the A and B zones of the Parkes error grid.

Realization of accurate blood glucose sensor using photonics based metamaterial

A new method is proposed in present communication to investigate the concentration of glucose in human blood using photonic metamaterial structure at 2 GHz frequency. Here 3 × 3 air holes are etched on 2D photonic structure containing blood sample manipulates with the high frequency structure simulator software, where two types of structures such as silicon and polymer metamaterial are considered for the sake of validations. 2D finite element simulation method divulges that linear variation of S11 parameter and feeble absorption bestows an accurate measurement of glucose in human blood using aforementioned photonic structure.

GLUCOSE CORRECTION IN HANDHELD DEVICES BY REDUCING THE EFFECT OF HEMATOCRIT

This study presents an approach for glucose correction in handheld devices by reducing the effects of hematocrit. The hematocrit values are estimated from the transduced current curves which are produced during the chemical reactions of glucose measurement process in the handheld devices. The hematocrit estimation is performed by applying the single-hidden layer feedforward neural network which is trained by the non-iterative learning algorithm. The experimental results show that the proposed approach can improve the accuracy of glucose measurement by using the handheld devices.

Hemoglobin A1C as an indicator of the accuracy of blood glucose measurement: comparative study of three technologies used for blood glucose measurements

In previous studies, the accuracy of glucose measurements were found with significant variations in different self-monitoring devices. This study suggests Hemoglobin a1c (Hba1c) to be used as as an indicator for the accuracy of blood-glucose monitoring devices. In this study, the association between the readings of glycohematoglobin HbA1C and the hyperglycemic readings of thirty hyperglycemic patients is used as an indicator of the accuracy of three types of glucometer devices. The association between hyperglycemic readings and the percentage of HbA1C for the same patients was investigated. The results showed significant association between levels of blood glucose and the percentage of HbA1C in three devices with statistically significant ( p &lt; 0.05). Such relationship is suggested to be used as a relative accuracy of various types of blood glucose self-monitoring devices.

Blood Gas Analyzer Accuracy of Glucose Measurements

ObjectiveTo investigate the comparability of glucose levels measured with blood gas analyzers (BGAs) and by central laboratories (CLs). Material and MethodsGlucose measurements obtained between June 1, 2007, and March 1, 2016, at the Vanderbilt University Medical Center were reviewed. The agreement between CL and BGA results were assessed using Bland-Altman, consensus error grid (CEG), and surveillance error grid (SEG) analyses. We further analyzed the BGAs’ performance against the US Food and Drug Administration (FDA) 2014 draft guidance and 2016 final guidance for blood glucose monitoring and the International Organization for Standardization (ISO) 15197:2013 standard. ResultsWe analyzed 2671 paired glucose measurements, including 50 pairs of hypoglycemic values (1.9%). Bland-Altman analysis yielded a mean bias of −3.1 mg/dL, with 98.1% of paired values meeting the 95% limits of agreement. In the hypoglycemic range, the mean bias was −0.8 mg/dL, with 100% of paired values meeting the 95% limits of agreement. When using CEG analysis, 99.9% of the paired values fell within the no risk zone. Similar results were found using SEG analysis. For the FDA 2014 draft guidance, our data did not meet the target compliance rate. For the FDA 2016 final guidance, our data partially met the target compliance rate. For the ISO standard, our data met the target compliance rate. ConclusionIn this study, the agreement for glucose measurement between common BGAs and CL instruments met the ISO 2013 standard. However, BGA accuracy did not meet the stricter requirements of the FDA 2014 draft guidance or 2016 final guidance. Fortunately, plotting these results on either the CEG or the SEG revealed no results in either the great or extreme clinical risk zones.

The FreeStyle Libre flash glucose monitoring system and the fasting month of Ramadan

The fasting month of Ramadan is a lunar month and Muslims abstain from eating, drinking, or using oral medications during this period. The duration of the fast starts before the beginning of dawn, ends at dusk and ranges between 12–19 hours. Management of diabetes during the fasting month of Ramadan can be challenging due to the amount and type of food consumption, physical activity, medications, and the duration of fasting. The main concern with fasting is the increased risk of hypoglycemia and hyperglycemia; therefore, capillary glucose monitoring is vital during Ramadan. The FreeStyle Libre (FSL) system (Abbott Diabetes Care, Alameda, CA, USA) is a unique interstitial system for monitoring glucose as it does not require user calibration. A patch sensor is fixed on the back of the upper arm and a hand reader is used to scan the sensor in order to receive the glucose readings. Several studies have shown that FSL is able to provide accurate glucose measurements when compared with capillary glucose blood results. The FSL results were not influenced by factors such as body mass index, age, type of diabetes, insulin administration, or hemoglobin A1c (HbA1c). The potential benefits of FSL were not tested during the months of Ramadan. Based on the safety and accuracy of FSL, further research is needed to assess the following: (I) whether the fast will have an impact on the accuracy of FSL; (II) how FSL can enable individuals with diabetes to complete the fast without encountering serious risks of hypoglycemia and hyperglycemia.