Showing papers on "Glucose Measurement published in 2018"
TL;DR: Invasive and noninvasive blood glucose monitoring methods using various biofluids or blood are described, highlighting the recent progress in the development of enzyme‐based glucose sensors and their integrated systems.
Abstract: Blood glucose concentration is a key indicator of patients' health, particularly for symptoms associated with diabetes mellitus. Because of the large number of diabetic patients, many approaches for glucose measurement have been studied to enable continuous and accurate glucose level monitoring. Among them, electrochemical analysis is prominent because it is simple and quantitative. This technology has been incorporated into commercialized and research-level devices from simple test strips to wearable devices and implantable systems. Although directly monitoring blood glucose assures accurate information, the invasive needle-pinching step to collect blood often results in patients (particularly young patients) being reluctant to adopt the process. An implantable glucose sensor may avoid the burden of repeated blood collections, but it is quite invasive and requires periodic replacement of the sensor owing to biofouling and its short lifetime. Therefore, noninvasive methods to estimate blood glucose levels from tears, saliva, interstitial fluid (ISF), and sweat are currently being studied. This review discusses the evolution of enzyme-based electrochemical glucose sensors, including materials, device structures, fabrication processes, and system engineering. Furthermore, invasive and noninvasive blood glucose monitoring methods using various biofluids or blood are described, highlighting the recent progress in the development of enzyme-based glucose sensors and their integrated systems.
420 citations
TL;DR: The NovioSense Glucose Sensor, worn under the lower eye lid (inferior conjunctival fornix), is reported to continuously measure glucose levels in the basal tear fluid with good correlation to blood glucose values, showing clear clinical feasibility in both animals and humans.
94 citations
TL;DR: It is confirmed that perioperative glucose control is related to surgical outcomes but that A1C, reflecting antecedent glycemia, is a less useful predictor.
Abstract: OBJECTIVE Hemoglobin A 1c (A1C) is used in assessment of patients for elective surgeries because hyperglycemia increases risk of adverse events. However, the interplay of A1C, glucose, and surgical outcomes remains unclarified, with often only two of these three factors considered simultaneously. We assessed the association of preoperative A1C with perioperative glucose control and their relationship with 30-day mortality. RESEARCH DESIGN AND METHODS Retrospective analysis on 431,480 surgeries within the Duke University Health System determined the association of preoperative A1C with perioperative glucose (averaged over the first 3 postoperative days) and 30-day mortality among 6,684 noncardiac and 6,393 cardiac surgeries with A1C and glucose measurements. A generalized additive model was used, enabling nonlinear relationships. RESULTS A1C and glucose were strongly associated. Glucose and mortality were positively associated for noncardiac cases: 1.0% mortality at mean glucose of 100 mg/dL and 1.6% at mean glucose of 200 mg/dL. For cardiac procedures, there was a striking U-shaped relationship between glucose and mortality, ranging from 4.5% at 100 mg/dL to a nadir of 1.5% at 140 mg/dL and rising again to 6.9% at 200 mg/dL. A1C and 30-day mortality were not associated when controlling for glucose in noncardiac or cardiac procedures. CONCLUSIONS Although A1C is positively associated with perioperative glucose, it is not associated with increased 30-day mortality after controlling for glucose. Perioperative glucose predicts 30-day mortality, linearly in noncardiac and nonlinearly in cardiac procedures. This confirms that perioperative glucose control is related to surgical outcomes but that A1C, reflecting antecedent glycemia, is a less useful predictor.
84 citations
TL;DR: In this paper, a novel hybrid nanocomposite material for glucose, which consisted of copper nanowires (Cu NWs), metal-organic frameworks (MOFs) and graphene oxide (GO) was prepared by an easy and convenient functionalization way through direct ultrasound mixing.
54 citations
TL;DR: The latent class analysis approach is a pathophysiologically insightful way to classify individuals without diabetes based on their response to glucose during an OGTT, which identified four different glucose response patterns that differed with regard to insulin sensitivity and acute insulin response, obesity, and plasma levels of lipids and inflammatory markers.
Abstract: OBJECTIVE Glucose measurements during an oral glucose tolerance test (OGTT) are useful in predicting diabetes and its complications. However, knowledge of the pathophysiology underlying differences in glucose curve shapes is sparse. We examined the pathophysiological characteristics that create different glucose curve patterns and studied their stability and reproducibility over 3 years of follow-up. RESEARCH DESIGN AND METHODS We analyzed data from participants without diabetes from the observational cohort from the European Group for the Study of Insulin Resistance: Relationship between Insulin Sensitivity and Cardiovascular Disease study; participants had a five–time point OGTT at baseline ( n = 1,443) and after 3 years ( n = 1,045). Measures of insulin sensitivity and secretion were assessed at baseline with a euglycemic-hyperinsulinemic clamp and intravenous glucose tolerance test. Heterogeneous glucose response patterns during the OGTT were identified using latent class trajectory analysis at baseline and at follow-up. Transitions between classes were analyzed with multinomial logistic regression models. RESULTS We identified four different glucose response patterns, which differed with regard to insulin sensitivity and acute insulin response, obesity, and plasma levels of lipids and inflammatory markers. Some of these associations were confirmed prospectively. Time to glucose peak was driven mainly by insulin sensitivity, whereas glucose peak size was related to both insulin sensitivity and secretion. The glucose patterns identified at follow-up were similar to those at baseline, suggesting that the latent class method is robust. We integrated our classification model into an easy-to-use online application that facilitates the assessment of glucose curve patterns for other studies. CONCLUSIONS The latent class analysis approach is a pathophysiologically insightful way to classify individuals without diabetes based on their response to glucose during an OGTT.
50 citations
TL;DR: The development of a table-top confocal Raman spectrometer that was used in the home of patients with diabetes and operated for extended periods of time unsupervised and without recalibration is reported on.
Abstract: One of the most ambitious endeavors in the field of diabetes technology is non-invasive glucose sensing. In the past decades, a number of different technologies have been assessed, but none of these have found its entry into general clinical use. We report on the development of a table-top confocal Raman spectrometer that was used in the home of patients with diabetes and operated for extended periods of time unsupervised and without recalibration. The system is based on measurement of glucose levels at a 'critical depth' in the skin, specifically in the interstitial fluid located below the stratum corneum but above the underlying adipose tissue layer. The region chosen for routine glucose measurements was the base of the thumb (the thenar). In a small clinical study, 35 patients with diabetes analyzed their interstitial fluid glucose for a period of 60 days using the new critical-depth Raman (CD-Raman) method and levels were correlated to reference capillary blood glucose values using a standard finger-stick and test strip product. The calibration of the CD-Raman system was stable for > 10 days. Measurement performance for glucose levels present at, or below, a depth of ~250μm below the skin surface was comparable to that reported for currently available invasive continuous glucose monitors. In summary, using the CD-Raman technology we have demonstrated the first successful use of a non-invasive glucose monitor in the home.
49 citations
TL;DR: An electrochemical enzymatic biosensor coated with red blood cell membrane (RBCM) significantly improved the selectivity and accuracy of the glucose measurement, even under human serum, compared to the uncoated sensors, implying that the RBCM serves well as a highly permselective layer to glucose molecules, and a diffusion barrier to other molecules.
46 citations
TL;DR: It is found that reconstitution of the acid mantle of skin may be seen in less than one hour, similar to continuous measurements for calibration spectra, and precleaning of the measurement site may be useful for intermittent, but not for long term continuous measurements.
Abstract: We have reported two methods to analyze glucose in the interstitial fluid of skin based on mid-infrared excitation with a tunable quantum cascade laser and photoacoustic or photothermal detection. These methods were evaluated for optimum skin locations to obtain reproducible glucose information. The lower part of the arm, the hypothenar, the tips of the index finger and the thumb were tested. The thumb appears to be the optimal skin location, followed by the index finger. Basic requirements for an optimum site are good capillary blood perfusion, low Stratum corneum thickness and the absence of fat layers. To obtain a correlation on such a site, spectra were recorded on volunteers continuously after blood glucose manipulation. However, continuous measurements on an in vivo sample such as the skin have to cope with physiological alterations such as the formation of sweat. We have used both detection schemes to investigate the acid mantle reformation after washing during time scales similar to continuous measurements for calibration spectra. We found that reconstitution of the acid mantle of skin may be seen in less than one hour. Precleaning of the measurement site may thus be useful for intermittent, but not for long term continuous measurements.
37 citations
TL;DR: In this article, a hierarchical platinum micro-/nanostructured electrode along with a novel measurement scheme leads to increased sensitivity, selectivity and stability compared to state-of-the-art.
33 citations
TL;DR: A cloud computing platform for automated monitoring of blood glucose levels is proposed to enable individuals with diabetes to connect with doctors and caretakers.
Abstract: Near infrared photoacoustic spectroscopy is utilized for the development of a continuous non-invasive glucose monitoring system for diabetics. A portable embedded system for taking photoacoustic measurements on tissues to estimate glucose concentration is implemented using field programmable gate array (FPGA). The back-end architecture for high-speed data acquisition and de-noising of photoacoustic measurements operates at 274.823 MHz on a Xilinx Virtex-II Pro FPGA. The glucose measurement technique is verified in vitro on glucose solutions and in vivo on tissues, with photoacoustic signal amplitude varying linearly with sample glucose concentration. A kernel-based regression algorithm using multiple features of the photoacoustic signal is used to estimate glucose concentration from photoacoustic measurements. The calibration algorithm provides a superior performance over previous efforts with a mean absolute relative difference of 8.84% and Clarke Error Grid distribution of 92.86% and 7.14% over Zones A and B of the grid. A cloud computing platform for automated monitoring of blood glucose levels is proposed to enable individuals with diabetes to connect with doctors and caretakers. The developed system is connected to the cloud service using a mobile device, which facilitates implementation of computationally intensive calibration tasks and the storage and analysis of measurement data for treatment and monitoring.
31 citations
TL;DR: The feasibility of detecting physiological glucose concentrations using NIR optoacoustic spectroscopy is demonstrated, enabling the sensing glucose with ±10 mg/dl precision.
Abstract: Glucose sensing is pursued extensively in biomedical research and clinical practice for assessment of the carbohydrate and fat metabolism as well as in the context of an array of disorders, including diabetes, morbid obesity and cancer. Currently used methods for real-time glucose measurements are invasive and require access to body fluids, with novel tools and methods for non-invasive sensing of the glucose levels highly desired. In this study, we introduce a near-infrared optoacoustic spectrometer for sensing physiological concentrations of glucose within aqueous media and describe the glucose spectra within 850-1900 nm and various concentration ranges. We apply the radiometric and dictionary learning methods with a training set of data and validate their utility for glucose concentration measurements with optoacoustics in the probe dataset. We demonstrate the superior signal-to-noise ratio (factor of ~3.9) achieved with dictionary learning over the ratiometric approach across the wide glucose concentration range. Our data show a linear relationship between the optoacoustic signal intensity and physiological glucose concentration, in line with the results of optical spectroscopy. Thus, the feasibility of sensing physiological glucose concentrations using near-infrared optoacoustic spectroscopy is demonstrated, enabling the sensing glucose with ±10 mg/dl precision.
TL;DR: A novel fiber attenuated total reflection (ATR) sensor with silver nanoparticles (AgNPs) on the flattened structure based on mid-infrared spectroscopy for detecting low concentration of glucose with high precision is proposed.
Abstract: This paper proposes a novel fiber attenuated total reflection (ATR) sensor with silver nanoparticles (AgNPs) on the flattened structure based on mid-infrared spectroscopy for detecting low concentration of glucose with high precision. The flattened structure was designed to add the effective optical path length to improve the sensitivity. AgNPs were then deposited on the surface of the flattened area of the fiber via chemical silver mirror reaction for further improving the sensitivity by enhancing the infrared absorption. Combining the AgNPs modified flattened fiber ATR sensor with a CO2 laser showed a strong mid-infrared glucose absorption, with an enhancement factor of 4.30. The glucose concentration could be obtained by a five-variable partial least-squares model with a root-mean-square error of 4.42 mg/dL, which satisfies clinical requirements. Moreover, the fiber-based technique provides a pretty good method to fabricate miniaturized ATR sensors that are suitable to be integrated into a microfluidic chip for continuous glucose monitoring with high sensitivity.
TL;DR: LCF showed a trend toward a modestly reduced mean glucose and significantly lower insulin requirements as compared with standard feeding but had no effect on glucose variability or time in target range.
Abstract: Background Enteral low-carbohydrate formulas (LCFs) could serve as a noninsulin alternative for the treatment of stress hyperglycemia in critically ill patients. We compared the glycemic effects of an LCF with a standard formula. Methods We conducted an open-label randomized trial in patients admitted to our intensive care unit between September 2015 and June 2016. Adult patients with an indication for enteral nutrition were randomized to an LCF (Glucerna 1.5 kcal) or a standard enteral formula (Fresubin Energy Fibre, with additional protein supplement). Primary outcome was glucose variability defined as mean absolute glucose (MAG) change (mmol/L/h). Secondary outcomes were mean glucose, time in target, hypoglycemic and hyperglycemic events, and insulin requirements. We assessed glycemic outcomes per blinded continuous glucose monitoring (CGM) system and compared outcomes with glucose measurements per blood gas analysis and point-of-care device. Results We randomized 107 patients (LCF: n = 53; standard: n = 54). Six patients had no CGM data, leaving 101 patients (n = 52; n = 49) for the intention-to-treat analysis. MAG change and time in target range were not different between groups. LCF gave a lower mean glucose measured per point-of-care device (7.8 ± 1.0 vs 8.4 ± 1.1 mmol/L, P = .007). LCF patients required significantly less insulin on the second study day (46.8 vs 68.0 IU, P = .036). Conclusion LCF showed a trend toward a modestly reduced mean glucose and significantly lower insulin requirements as compared with standard feeding but had no effect on glucose variability or time in target range.
TL;DR: The proposed GSPA method provides a solution to enhance sensitivity, facilitating development of portable and low-cost PA sensors with low power laser diodes for noninvasive glucose monitoring and other applications.
Abstract: A novel “guide star” assisted photoacoustic (GSPA) method for noninvasive glucose measurement has been proposed. Instead of receiving PA signals that are directly generated by tissue, a virtual photodiode is employed to amplify the PA signal difference regarding amplitude and peak arrival time caused by glucose concentration variations in an indirect way. Being different from traditional PA spectroscopy, this method can improve sensitivity and accuracy by optimizing optical path lengths (or tissue thickness). On the other hand, being superior to near-infrared (NIR) spectroscopy, it utilizes both optical absorption and acoustic propagation velocity information confered by PA signals. Theoretical analysis and simulation have been done to illustrate how the concentration change affects the PA waveform. In vitro experiments on aqueous glucose solution were conducted with concentrations varying in human physiological range (50–350 mg/dL). Performance of quartz cuvettes with 1 mm and 2 mm optical path lengths w...
TL;DR: Comparing three approaches to enzyme immobilization on the microelectrode surface-physical adsorption, hydrogel entrapment, andEntrapment in electrospun nanofibers suggests that each of these methods can be used to create functional microbiosensors.
Abstract: Electrochemical monitoring of non-electroactive species requires a biosensor that is stable and selective, with sensitivity to physiological concentrations of targeted analytes. We have combined glucose oxidase-modified carbon-fiber microelectrodes with fast-scan cyclic voltammetry for real-time measurements of glucose fluctuations in brain tissue. Work presented herein quantitatively compares three approaches to enzyme immobilization on the microelectrode surface-physical adsorption, hydrogel entrapment, and entrapment in electrospun nanofibers. The data suggest that each of these methods can be used to create functional microbiosensors. Immobilization of glucose oxidase by physical adsorption generates a biosensor with poor sensitivity to glucose and unstable performance. Entrapment of glucose oxidase in poly(vinyl alcohol) nanofibers generates microbiosensors that are effective for glucose measurements over a large linear range, and that may be particularly useful when targeting glucose concentrations in excess of 3 mm, such as in blood. Hydrogel entrapment is the most effective in terms of sensitivity and stability. These microbiosensors can be used for simultaneous monitoring of glucose and dopamine in real time. The findings outlined herein should be applicable to other oxidase enzymes, and thus they are broadly important for the development of new tools for real-time measurements of fluctuating molecules that are not inherently electroactive.
TL;DR: In this article, the authors demonstrate a thin, flexible sensor and an associated wireless readout integrated circuit (IC) that can be used to continuously monitor glucose level over a very wide glucose concentration range.
Abstract: Glucose is a central substance in the human metabolism, and its concentration in human body fluid can reflect various diseases and organ malfunctions. We demonstrate a thin, flexible sensor and an associated wireless readout integrated circuit (IC) that can be used to continuously monitor glucose level over a very wide glucose concentration range. The sensor is fabricated on flexible and robust graphene petals deposited on thin carbon fibers with biocompatible materials. Graphene petals offer sensitivity of 5.67 μAmM−1 cm-2 with a sensing range from 2 μM to 66 mM. Mechanical properties of the graphene petals provide a sensor lifetime exceeding four weeks. The readout IC harvests magnetic energy from a nearby power source, acquires glucose information, and wirelessly transmits data to the user. Linearity of analog/digital circuit blocks are verified by amperometric glucose measurements while consuming less than 21μW. The sensor and readout system can be readily integrated with other sensors or drug-delivery actuators for diagnosis and therapies for diabetes.
TL;DR: Calculating the meal insulin requirements based on the carbohydrate and protein content may have advantages over calculations based on carbohydrate alone, and further studies are required to determine how to best optimize this.
Abstract: This randomized controlled cross-over study compared postprandial glucose concentrations and incidence of hypoglycaemia for mealtime bolus insulin calculated for both meal protein and carbohydrate content, with ordinary dosing for carbohydrate content alone, in adults with type 1 diabetes who usually follow a carbohydrate-restricted diet. All 16 participants completed three test meals under each of the two conditions. The primary outcome was the time normalized Area Under the Curve (AUC) of glucose measurements. The mean (SD) AUC glucose concentration for insulin dosing for both protein and carbohydrate was 8.3 (2.1) mmol/L compared with 10.0 (2.2) mmol/L for carbohydrate alone. The difference (95% CI) was -1.76 mmol/L (-2.87 to -0.65), P = .003. The mean (SD) glucose concentration ≥ 8.0 mmol/L was 54.8 (32.4)% for dosing for protein and carbohydrate and 73.7 (26.3)% for carbohydrate alone, rate ratio (95% CI) 0.75 (0.62 to 0.89), P = .002. For glucose concentration < 4.0 mmol/L 5.5 (15.1)% and 2.8 (11.7)%; rate ratio (95% CI): 1.97 (0.90 to 4.27), P = .087. Calculating the meal insulin requirements based on the carbohydrate and protein content may have advantages over calculations based on carbohydrate alone. Further studies are required to determine how to best optimize this.
TL;DR: Reporting blood glucose monitoring data would help to interpret the CGM data at least in the context of time spent in various glucose ranges as a parameter with which quality of diabetes therapy is measured.
Abstract: Recently, two clinical trials about a "sensor-based flash glucose monitoring system" and its efficacy in reducing time in hypoglycemia were published. Interestingly, patients spent more time at low glucose concentrations in these studies than in other studies related to the efficacy of real-time continuous glucose monitoring (rtCGM). Although it is possible that the study populations differed from those in other studies, another potential explanation is that the CGM system used in these two studies had a negative glucose measurement bias. Such a negative bias was reported in recent literature, suggesting that the CGM system may inaccurately indicate hypoglycemia. Reporting blood glucose monitoring data would help to interpret the CGM data at least in the context of time spent in various glucose ranges as a parameter with which quality of diabetes therapy is measured.
TL;DR: The HemoCue point-of-care system is accurate for dysglycemia screening in patients with CAD according to Bland-Altman, the surveillance error grid, and Spearman correlation test.
Abstract: Background: Point-of-care equipment for measuring glucose saves time and costs for both patients and professionals and minimizes preanalytic errors when screening for or managing dysglycem...
TL;DR: Both sensors had good clinical accuracy, when used with the CGMS iPro2, but the analytical accuracy was below the minimum set by ISO 15197:2013.
TL;DR: An amplitude-stabilized wavelength-tunable single-mode external cavity diode laser operating around 1050 nm was realized and characterized for the use of laser beam as an excitation light source in this article.
Abstract: The present paper focuses on development of a compact photo-acoustic sensor using inexpensive components for glucose analysis. An amplitude-stabilized wavelength-tunable single-mode external cavity diode laser operating around 1050 nm was realized and characterized for the use of laser beam as an excitation light source. In the established setup, a fine tuning range of 9 GHz was achieved. The glucose solution was obtained by diluting D-glucose in sterile water. The acoustic signal generated by the optical excitation was detected via a chip piezoelectric film transducer. A detection limit of 50 mM (900 mg/dl) was achieved. The device may be of great interest for its applications in medicine and health monitoring. The sensor is promising for non-invasive in vivo glucose measurements from interstitial fluid.
TL;DR: It is observed from the generalized sensitivity analysis of the minimal model of the intravenous glucose tolerance test that the measurements of insulin, 62 min after the administration of the glucose bolus into the experimental subject's body, possess no information about the parameter estimates.
Abstract: Generalized sensitivity functions characterize the sensitivity of the parameter estimates with respect to the nominal parameters. We observe from the generalized sensitivity analysis of the minimal model of the intravenous glucose tolerance test that the measurements of insulin, 62 min after the administration of the glucose bolus into the experimental subject’s body, possess no information about the parameter estimates. The glucose measurements possess the information about the parameter estimates up to three hours. These observations have been verified by the parameter estimation of the minimal model. The standard errors of the estimates and crude Monte Carlo process also confirm this observation.
TL;DR: Glucose concentrations measured in recommended ice-chilled lithium heparin- and citrate buffer-containing tubes are not comparable; therefore, they cannot be used interchangeably.
Abstract: Background The aim of our study was to determine the difference between glucose concentration measured 30 min after venipuncture in ice-chilled heparin plasma sample and all currently available citrate buffer-containing tubes (Greiner Glucomedics, Greiner FC Mix and Sarstedt GlucoEXACT) and still widely used sodium fluoride/potassium oxalate (NaF/Kox) tubes from Greiner. Methods Blood was collected from 20 healthy volunteers and 20 patients with diabetes into LiH, NaF/KOx, Glucomedics, FC mix and GlucoEXACT tubes. Glucose was measured within 30 min from blood sampling in duplicate on the Architect c8000 analyzer. Mean biases between all tube types were calculated and compared to the recommended criteria (1.95%). Additionally, glucose concentrations measured in all five tube types were compared using the Friedman test. Results In the entire studied population, glucose concentrations measured in Glucomedics, FC mix and GlucoEXACT were higher (7.3%, 3.2% and 2.0%, respectively) than in the ice-chilled LiH tubes. When all glycolysis inhibitor-containing tubes were compared, Glucomedics tubes significantly differed from GlucoEXACT and FC mix tubes (biases -4.9% and 4.0%, respectively). In addition, there was a significant difference between the NaF/KOx tube and Glucomedics, as well as FC mix tubes (biases 7.1% and 3.0%, respectively). Conclusions Glucose concentrations measured in recommended ice-chilled lithium heparin- and citrate buffer-containing tubes are not comparable. Significant biases exist between various glycolysis inhibitor-containing tubes; therefore, they cannot be used interchangeably.
27 May 2018
TL;DR: A novel noninvasive microwave biosensor for glucose measurement was designed, developed and tested to show its potential for real-time and continuous glucose monitoring and showed significant accuracy improvement compared to single parameter based magnitude and frequency predictions.
Abstract: A novel noninvasive microwave biosensor for glucose measurement was designed, developed and tested to show its potential for real-time and continuous glucose monitoring. The reflected S-parameter S11 was investigated with different glucose concentrations within the range of 0.5 ∼ 7 g/dL. The magnitude and resonance frequency information were utilized for prediction and then combined by data fusion to enhance the accuracy. The prediction results by magnitude and resonance frequency of S11 versus reference glucose concentration show root-mean-squared errors (RMSE) of 0.2887 g/dL and 0.1681 g/dL respectively. The prediction by data fusion shows RMSE value of 0.1364 g/dL indicating significant accuracy improvement of 52.75% and 18.86% compared to single parameter based magnitude and frequency predictions.
TL;DR: The investigated unit-use POCT method is suitable for the diagnosis of IGT and DM when venous blood samples are collected, and changes in measurement procedures can introduce a bias and affect diagnosis rates, thereby emphasizing the need for further harmonization of glucose methods.
Abstract: The use of glucose point-of-care testing (POCT) devices for the diagnosis of diabetes mellitus (DM) is an ongoing controversy. In patient management, glucose concentrations are determined by POCT and core laboratory glucose methods, and the values are commonly compared even though the samples collected are different, namely, capillary whole blood and venous plasma. In individual patients it is difficult to distinguish between factors that can influence the results, such as sample type and measuring procedure. In this study, glucose concentrations obtained using POCT and core laboratory instruments were assessed to duplicate typical scenarios experienced in healthcare. Corresponding diagnosis rates of impaired glucose tolerance (IGT) and DM based on fixed, method-independent cutoffs were compared. Glucose concentration was measured by the 2-h oral glucose tolerance test (OGTT) in samples collected from an inpatient cohort and a cohort from the general population. Two POCT methods, namely, a handheld unit-use glucometer and a small bench-top analyzer with batch reagents, and two core laboratory procedures were used to measure glucose concentrations. The sample types were whole blood and plasma samples collected from venous and capillary blood. The glycated hemoglobin level in whole blood was also determined. A total of 231 subjects were included in the study. The 2-h OGTT glucose concentrations in the capillary whole blood samples showed a positive bias of 0.8 mmol/L compared to those obtained using core laboratory plasma glucose methods, leading to increased rates of diabetes diagnosis. This bias decreased to 0.2 mmol/L when venous blood was used in the tests. A change in the method used by the core laboratory introduced a negative bias of 0.5 mmol/L and, consequently, a lower diagnosis rates. Venous blood samples measured at the point-of-care are the most suitable sample type for the measurement of the glucose concentration in the 2-h OGTT. The investigated unit-use POCT method is suitable for the diagnosis of IGT and DM when venous blood samples are collected. Importantly, changes in measurement procedures can introduce a bias and affect diagnosis rates, thereby emphasizing the need for further harmonization of glucose methods. A plain language summary is available for this article. In clinical practice, a physician may be confronted with blood glucose concentrations determined using different devices. It is difficult for the treating physician to assess the effect of factors that can impact the glucose measurement, such as sample type and measuring procedure, for a given glucose concentration result. The aim of this study was to duplicate typical scenarios in the healthcare setting in terms of differences in glucose concentrations in capillary and venous samples obtained using a handheld point-of-care testing device, one benchtop device, and two core laboratory instruments. The diagnosis rates of impaired glucose tolerance and diabetes mellitus were compared to demonstrate the effects of the glucose concentrations measured using these different devices in terms of clinical response. We performed an oral glucose tolerance test and obtained the blood glucose concentration immediately before and 2 h after an oral glucose load. The results were compared and presented using difference and scatter plots. A total of 231 subjects were included in the study. Glucose concentrations in capillary whole blood samples showed a positive bias compared to those determined using core laboratory methods, leading to increased rates of diabetes diagnosis. This bias decreased when venous whole blood samples were used. A change in the method used in the core laboratory introduced a negative bias and, consequently, lower diagnosis rates. Changing laboratory devices can introduce a bias that is sufficiently large as to affect the diagnosis of diabetes since the latter is based on method-independent cutoffs. From these findings we conclude that both of the point-of-care devices investigated are suitable for the diagnosis of diabetes when venous samples are used. Our findings also emphasize the need for further harmonization of the glucose testing method.
TL;DR: A novel analytical strategy where the intrinsic advantages of PQQGDH are combined with the Enzyme Thermistor as biosensor using calorimetric detection as general measurement principle resulted in an excellent specificity and insignificant side effects of compounds present in blood at high concentrations, such as lactate and urea.
Abstract: A broad measurement range of glucose is often required in clinical analysis, especially for diabetic patients where glucose levels can be very high. Pyrroloquinoline quinone glucose dehydrogenase (PQQGDH) has previously been used in electrochemical quantification of glucose with an extended linear range. However, in real sample determination of glucose, interferences from electroactive substances in blood are unavoidable. Calorimetric biosensors, e.g., the Enzyme Thermistor, are insensitive to either directly electroactive or optical interferences often present in real clinical samples. This paper describes a novel analytical strategy where the intrinsic advantages of PQQGDH are combined with the Enzyme Thermistor as biosensor using calorimetric detection as general measurement principle. When compared with the most frequently used enzyme glucose oxidase, PQQGDH has a higher catalytic efficiency and is insensitive to the availability of oxygen. The use of calorimetry in this context resulted in a broad linear range of glucose measurements, from 0.009 to 100 mM, an excellent specificity and insignificant side effects of compounds present in blood at high concentrations, such as lactate and urea.
TL;DR: The aim and objective of this study is to correlate the skin resistance based on Galvanic skin response (GSR) and blood glucose level for diabetic and non-diabetic subject and to estimate the blood glucose value based on GSR voltage and resistance using stepwise linear regression model.
Abstract: Diabetes is a chronic disease due to the lack of production of hormone insulin by the beta cells in the islets of Langerhans. Many diabetic patients often draw a small amount of blood to measure the glucose level every day. This vital information is needed to control their daily food intake. One such method could cause infection and discomfort to the patient. Non-invasive glucose measurement techniques overcome these challenges to monitor blood glucose level continuously. The aim and objective of this study are as follows: (i) to correlate the skin resistance based on Galvanic skin response (GSR) and blood glucose level for diabetic and non-diabetic subject and (ii) to estimate the blood glucose value based on GSR voltage and resistance using stepwise linear regression model. About 50 diabetic and 50 non-diabetic subjects were included in this study. Blood glucose level is recorded using the minimally invasive device called accu-chek for all the subjects. GSR resistance and GSR voltage were recorded using...
14 Jun 2018
TL;DR: In this paper, absorbance principle is used to propose the non-invasive blood glucose monitoring design aspect and it has been found that, 940nm wavelength is more precise to detect the glucose concentration.
Abstract: Diabetes is an incurable disorder which produces various problems related to the body. It is a fast growing disorder, about 500 million people in the world and 50 million people in India are the victims of diabetes. All problems related to diabetes can be reduced through physical exercise, proper and balanced diet, and medication. The current invasive technique which is painful and inconvenient because people have to prick their finger to draw the blood for the measurement of glucose concentration in the blood on a daily basis so it is not recommended for a lifetime. People living in villages (economically poor) do not have facilities to check their blood sugar level regularly because of unavailability of glucose measurement devices and procedural cost. In this paper, absorbance principle is used to propose the non-invasive blood glucose monitoring design aspect. In the spectrometer experiment it has been found that, 940nm wavelength is more precise to detect the glucose concentration. Using Near-Infrared spectroscopy, The IR light passes through the finger, after amplification and filtering we get photo-plethysmograph signal as a result. From the result, we analyze the voltage variations and glucose for different samples and we observed that there is a linear relationship between voltage and glucose concentration. Microcontroller (MSP 430) is further used to display the glucose level on LCD and this data can be sent to the doctors through an android app so that patient can get early medications.
01 Dec 2018
TL;DR: In this paper, a cost-effective design of electrochemical based biosensor for nonenzymatic glucose detection in urine was presented, by incorporating low-cost, non-precious cobalt (Co)/iron (Fe) metals, the sensor was employed onto the three-electrode system for quantifying glucose level from 0 to 3.
Abstract: We presented a cost-effective design of electrochemical based biosensor for non-enzymatic glucose detection in urine. By incorporating low-cost, non-precious cobalt (Co)/iron (Fe) metals, the sensor was employed onto the three-electrode system for quantifying glucose level from 0 to 3.25 mM in artificial urine medium and clinical simulated urine solution, namely, Surine. In particular, the fabricated CoFe nanoparticles on N-doped graphene (NG) biosensor was assessed electrochemical performances by cyclic voltammetry and amperometry at applied potential of +0.90 V versus Ag/AgCl, in comparison with that of CoFe on carbon supported. Based on the results, it was found that two processes of catalytic oxidation and oxide depletion are involved in glucose detection. More importantly, the as-prepared biosensor exhibited an outstanding sensitivity of 476.67 µA.cm−2.mM−1 with R2 of 0.9974 in Surine. Furthermore, the low limit of detection was estimated to be 37.7 µM (signal-to-noise ratio of 3) with an excellent anti-interference property toward ascorbic acid, uric acid, and chlorine ions, providing a promising advancement for future glucose measurement in urine, applicable for sustainable diabetic prognosis and management.