Measurement Of Glucose Concentration Research Articles

Harnessing Redox Polymer Dynamics for Enhanced Glucose-Oxygen Coupling in Dual Biosensing and Therapeutic Applications.

The burgeoning field of continuous glucose monitoring (CGM) for diabetes management faces significant challenges, particularly in achieving precise and stable biosensor performance under changing environmental conditions such as varying glucose concentrations and O2 levels. To address this, we present a novel biosensor based on the electroless coupling of glucose oxidation catalyzed by flavin-dependent glucose dehydrogenase (FAD-GDH) and O2 reduction catalyzed by bilirubin oxidase (BOD) via a redox polymer, dimethylferrocene-modified linear poly(ethylenimine), FcMe2-LPEI. Initial cyclic voltammetry tests confirm the colocalization of both enzymatic reactions within the potential range of the polymer, indicating an effective electron shuttle mechanism. As a result, we created a hybrid biosensor that operates at open-circuit potential (OCP). It can detect glucose concentrations of up to 100 mM under various O2 conditions, including ambient air. This resulted from optimizing the enzyme ratio to 120 ± 10 mUBOD·UFAD-GDH-1·atmO2-1. This biosensor is highly sensitive, a crucial feature for CGM applications. This distinguishes it from FAD-GDH traditional biosensors, which require a potential to be applied to measure glucose concentrations up to 30 mM. In addition, this biosensor demonstrates the ability to function as a noninvasive, external device that can adapt to changing glucose levels, paving the way for its use in diabetes care and, potentially, personalized healthcare devices. Furthermore, by leveraging the altered metabolic pathways in tumor cells, this system architecture opened up new avenues for targeted glucose scavenging and O2 reduction in cancer therapy.

Wearable, disposable and non-enzymatic fluorescence nanosensor for monitoring sweat glucose through smartphone

The promise of non-invasive health monitoring has fuelled the development of wearable biosensors for in situ detection of biological analytes in sweat. This paper presents a new fluorescent nanosensor probe based on boric acid functionalized and heteroatom doped carbon quantum dots (CQDs) embedded in paper-based analytical devices and integrated with a hydrophilic cotton thread-based microfluidic channel for the development of a flexible, wearable, biocompatible, and biodegradable sweat sensor for real-time measurement of sweat glucose concentration via smartphone readout. The morphological, physiochemical, compositional, crystallinity, and optical properties of nanosensors were extensively investigated. CQD particle sizes were found to be widely dispersed, ranging from 2.6 to 7.1 nm, with an average diameter of 4.38 nm. A dual response via fluorescence and colorimetric change was demonstrated for on-site sweat glucose monitoring using a smartphone camera to capture images in RGB (red, green, and blue) format and analyse them simultaneously by a customized android app, with quantitative results displayed on the smartphone. The limit of detection value for in situ measurement of sweat glucose concentration was 1.40 to 2.00 μM (25.25 to 36.13 μg/dL) and the limit of quantification value was 4.67 to 6.69 μM (84.16–120.44 μg/dL) in the pH range of 4.5 to 7.5. The developed sensor's performance metrics were validated using a standard clinical technique, which indicates strong correlation between two methods with Pearson correlation coefficient values of 0.83 and 0.80 for non-diabetic and type- II diabetes patients, respectively. Besides, interference, spike, and recovery studies were carried out with recovery rates ranging from 96.5 to 105.8 %, demonstrating good repeatability and reproducibility. Furthermore, feasible fluorescence quenching processes have been explored. In addition, the disposable and biodegradable nature of the nanosensor probe was studied by throwing it into the soil in the natural environment, where it dissolves almost spontaneously after three weeks.

Non-invasive measurements of blood glucose levels by time-gating mid-infrared optoacoustic signals

Non-invasive glucose monitoring (NIGM) represents an attractive alternative to finger pricking for blood glucose assessment and management of diabetes. Nevertheless, current NIGM techniques do not measure glucose concentrations in blood but rely on indirect bulk measurement of glucose in interstitial fluid, where glucose is diluted and glucose dynamics are different from those in the blood, which impairs NIGM accuracy. Here we introduce a new biosensor, termed depth-gated mid-infrared optoacoustic sensor (DIROS), which allows, for the first time, non-invasive glucose detection in blood-rich volumes in the skin. DIROS minimizes interference caused by the stratum corneum and other superficial skin layers by time-gating mid-infrared optoacoustic signals to enable depth-selective localization of glucose readings in skin. In measurements on the ears of (female) mice, DIROS displays improved accuracy over bulk-tissue glucose measurements. Our work demonstrates how signal localization can improve NIGM accuracy and positions DIROS as a holistic approach, with high translational potential, that addresses a key limitation of current NIGM methods.

Ultra-sensitive fiber optic sensor for glucose concentration measurement based on Vernier effect in cascaded Mach–Zehnder interferometers

In this paper, a fiber optic glucose concentration sensor based on cascaded Mach–Zehnder interferometers (CMZIs) was proposed and experimentally verified. Two single-mode fibers (SMFs) with slightly different tapering lengths and as well free spectral ranges (FSRs) were obtained through the melt-drawn cones technique and then were cascaded together to achieve the Vernier effect (VE). Experimental results showed that the measurement sensitivity of glucose concentration based on a single tapered SMF was 0.0494 nm (mmol l−1)−1. Furthermore, the measurement sensitivity based on the cascaded tapered SMFs was enhanced by 4.86 times to an ultra-high level of 0.2402 nm (mmol l−l)−1. The resolution reached 0.083 mmol l−1. The refractive index sensitivity reached 9066 nm/RIU. The resolution reached 2.21 × 10−6 RIU. In addition, the proposed glucose concentration sensor based on CMZIs shows good hysteresis. In conclusion, the designed sensor, showing the merits of easy to fabricate, high sensitivity, and high detection resolution, could be used to monitor the tiny variation in glucose concentration.

Effects of Physalis peruviana L. (leaf crude extracts) on blood glucose and functional biomarkers in streptozotocin-nicotinamide-induced diabetic rats.

Promoting antidiabetic phytomedicines necessitates evidence-based preclinical investigations, particularly in animal models. The present study investigated the validity of using the streptozotocin-nicotinamide-induced type 2 diabetic (STZ/NA-induced T2DM) model to evaluate the effects of Physalis peruviana leaf crude extracts on controlling blood glucose levels and regulating physiological biomarkers in rats. Aqueous and methanol extracts dissolved in carboxymethylcellulose 1% (100, 200, mg/kg/day) were administered orally to STZ/NA-induced T2DM rats alongside glibenclamide (5 mg/kg) as the standard drug for four weeks. Blood samples were collected in fasting rats on days 1, 7, 14, 21, and 28 to measure glucose concentration, lipoprotein-cholesterol, and common serum biomarkers. Nutrition characteristics were also monitored, as well as the pancreas histology. Administration of STZ/NA in Wistar rats induced the T2DM significantly lower than did STZ alone (glycaemia 200 vs 400 mg/dL). The significant effects observed with plant extracts compared to untreated diabetic rats were blood glucose reduction (28-52 %), HDL-C increase, LDL-C decrease, ALAT increase, WBC increase, body weight gain (24%), and pancreas protection. The findings confirm the antidiabetic effect of P. peruviana in T2DM animal model.

Metabolic Effects of Brown Adipose Tissue Activity Due to Cold Exposure in Humans: A Systematic Review and Meta-Analysis of RCTs and Non-RCTs.

Brown adipose tissue (BAT), specialized in thermoregulation in mammals, has been linked to improved glucose and lipid homeostasis when activated by cold exposure (CE). This systematic review and meta-analysis assessed the metabolic effects of CE-induced BAT activation in healthy humans, examining changes in glucose and lipid metabolism compared to thermoneutrality (TN). A literature search was conducted, identifying relevant human studies, including randomized controlled trials (RCTs) and non-RCTs, based on predefined inclusion criteria. Seven studies (a total of 85 participants) fully met the criteria. Data on plasma glucose, insulin, triglycerides (TGs), and free fatty acids (FFAs) were extracted for meta-analysis. When comparing TN and CE under fasting conditions, there were no significant changes in glucose, insulin, or TG concentrations (all p > 0.36). In contrast, CE significantly increased FFA concentrations (p = 0.002; n = 38). Bias was absent for all parameters, but heterogeneity was observed for insulin (I2 = 74.8%). CE primarily affects FFA concentration, likely reflecting cold-induced BAT activity. This suggests that circulating FFAs, serving as the primary fuel for thermogenesis, could indicate BAT activation. However, understanding the effects of BAT activation on overall metabolism requires a broader approach beyond fasting glucose and lipid concentration measurements.

The sodium correction factor for dogs undergoing treatment for a hyperglycemic crisis is a 1.6-mEq/L decrease in sodium per 100-mg/dL increase in glucose.

To determine the sodium correction factor for clinical use in hyperglycemic diabetic dogs. Retrospective analysis of 76 hospitalization episodes from 67 different dogs presenting to the University of Georgia Veterinary Teaching Hospital between January 1, 2015, and January 1, 2023. For each hospitalization episode, paired blood sodium and glucose concentration measurements were recorded from the time of presentation until glucose concentration was ≤ 201 mg/dL. Therapies administered, primary diagnosis, and concurrent diseases were also recorded for each episode. A linear mixed model was used to determine the sodium correction factor per 100-mg/dL increase in glucose. Piecewise linear mixed models were also constructed for blood glucose measurements ≤ 400 mg/dL and > 400 mg/dL to explore potential correction factor differences between low and high glucose concentrations. A sodium correction factor of a 1.6-mEq/L (95% CI, 1.3 to 1.9 mEq/L) decrease in sodium concentration per 100-mg/dL increase in blood glucose concentration was calculated. Differences in the correction factor between conditions of low and high glucose concentrations could not be determined due to a small sample size of blood glucose values > 400 mg/dL. Most dogs received similar treatments throughout the study period, including balanced isotonic crystalloids (97% [74/76]), electrolyte supplementation (84% [64/76]), and regular insulin (97% [74/76]). Almost all patients (93% [71/76]) had 1 or more concurrent diseases. A sodium correction factor of 1.6 mEq/L (decrease in sodium per 100-mg/dL increase in glucose) is recommended for clinical use in hyperglycemic diabetic dogs.

A Novel Biosensor for the Detection of Glucose Concentration Using the Dual-Peak Long Period Grating in the Near- to Mid-Infrared.

In this article, we demonstrate an improved efficient fibre sensor with a high sensitivity to measure glucose concentrations in the physiological range of human beings, operating in a broad spectral bandwidth from the near- to mid-infrared. The sensor consists of a dual-peak long period grating (DPLPG) with a period of 150 μm inscribed in an optical fibre with a diameter of 80 μm. The investigation of sensing for refractive index results in a sensitivity of ~-885.7 nm/refractive index unit (RIU) and ~2008.6 nm/RIU in the range of 1.30-1.44. The glucose measurement is achieved by the immobilisation of a layer of enzyme of glucose oxidase (GOD) onto the fibre surface for the selective enhancement of sensitivity for glucose. The sensor can measure glucose concentrations with a maximum sensitivity of -36.25 nm/(mg/mL) in the range of 0.1-3.0 mg/mL. To the best of our knowledge, this is the highest sensitivity ever achieved for a measurement of glucose with a long period grating-based sensor, indicating its potential for many applications including pharmaceutical, biomedical and food industries.

High concordance of blood glucose measurement in cats between a beta prototype glucometer device and a reference laboratory standard in a clinical setting.

The objective of this study was to evaluate the accuracy of a beta prototype version of a new portable blood glucose meter in feline patients. 60 client-owned cats. In this prospective study, 3-mL blood samples were collected from each cat and analyzed in triplicate using a beta prototype device (AlphaTRAK 3 [AT3]) and by a reference lab standard immediately after collection. Accuracy of the AT3 device was determined in accordance with the International Organization of Standardization (ISO) 15197:2013 criteria, including Bland-Altman plotting and consensus error grid analysis. A Passing-Bablok regression analysis was also performed. 96% of feline measurements fell within the ISO accuracy threshold, and 100% of measurements fell within zones A and B of the consensus error grid, meeting the ISO accuracy requirements. There was no significant bias in the data according to the Bland-Altman analysis. Within the full range of glucose concentrations (20 to 750 mg/dL) the correlation coefficient between the AT3 and the reference lab standard was 0.99. There was no significant constant or proportional bias present in the data. The AT3 device met the ISO requirements and is accurate for measurement of blood glucose concentrations in cats.

On Standardization and Evaluation of Continuous Glucose Monitoring Systems

Continuous glucose monitoring (CGM) systems are often used to monitor blood glucose levels. Most commercially available CGM systems continuously measure glucose concentrations in the interstitial fluid of subcutaneous adipose tissue. However, there is currently no internationally accepted reference method for measuring interstitial fluid glucose, which is a prerequisite for metrological traceability of glucose measurements obtained using CGM. Since manufacturers do not provide information about the traceability chain and measurement uncertainty of their systems, CGM-derived glucose values cannot currently be adequately traced to standards or higher order reference measurement procedures. Additionally, the «mean absolute relative difference» (MARD) often used to describe the analytical performance of CGM systems is dependent on many factors. For example, the MARD can be significantly affected by the «lag time» between the change in blood glucose and interstitial glucose, especially at high rates of change in glucose. Finally, modern automated insulin delivery (ADI) systems with integrated CGM can automatically suspend or increase insulin infusion in response to current and/or predicted hypoglycemic and hyperglycemic phenomenon in children and adults with type 1 diabetes mellitus (T1DM). The purpose of the review is justification of the necessity to establish metrological traceability of glucose measurements with CGM systems, as well as a discussion of the analytical and clinical characteristics of CGM systems proposed by various professional communities. Based on the results of the review, it was concluded that it is necessary to 1) develop metrological support for glucose measurements performed using CGM systems, 2) solve the problems of ensuring the accessibility and usability of CGM systems by patients in real conditions.

Estimation of foliar glucose content of areca palm by a smartphone app and Fourier transform infrared spectroscopy based multivariate modeling

Carbohydrates are essential molecules in the metabolism of plant systems whose quantification is crucial. The study aims to estimate foliar glucose content using the Smartphone-based Color Grab app by color change upon reaction with a 3,5-dinitrosalicylic acid reagent and mid-infrared spectra. The hue showed a negative correlation of − 0.959 with glucose content with sensitivity, detection limit and precision of 13.46 μg/mL,μg/mL,0.035 μg/mL, and 0.229% respectively. The glucose concentration to color coordinates displayed a linear response between 50 to 600 µg/mL. The linear regression equation with hue of standards was used to predict spectrophotometrically measured glucose concentration of leaf extracts with R2 = 0.934 and sensitivity of 13.46 μg/mL. Multivariate analysis of infrared spectrum (650–4000 cm‐1−1) of powdered arecanut leaves indicated elastic net and partial least square regression as the best models with R2 of 0.99. The study has practical implications in smartphone or infrared spectra-based glucose measurements for low glucose (< 1 mg/mL) samples.

Comparison of Two Methods for the Measurement of Blood Plasma and Capillary Blood Glucose in Tropical Highland Grassing Dairy Cows.

(1) Background: There is lack of published studies validating specific cow-side glucometers such as Centrivet GK (CVGK). (2) Methods: The aims were (1) to measure and compare the blood glucose concentrations in 52 tropic highland grassing cows by using CVGK and the traditional enzymatic/photometric assay (EPA) in plasma and serum (reference method) and (2) to establish if glucose concentrations obtained via these methods could be affected by several demographic and zootechnical parameters of the dairy herd evaluated. (3) Results: Glucose concentrations were significantly (p = 0.00) affected by the method used for their measurement. The intra-assay coefficient of variation (CV) for glucose concentrations in plasma EPA and for CVGK was 14% for both methods with serum EPA, whereas the inter-assay CV for plasma EPA and CVGK was 8% and 13.7%, respectively, with serum EPA. Pearson correlation coefficient calculations between the reference method in serum and plasma presented a slightly positive significant (p = <0.000) correlation (r = 0.56), whereas there was not a significant (p = 0.413) correlation between serum EPA and CVGK (r = 0.135). The Passing and Bablok regressions were out of the ideal expected values for the slope (β = 1) and the intercept (α = 0) (11), whereas the Bland-Altman plots showed a bias of 5.29 ± 11.73 (mg/dL) for serum and plasma and 11.01 ± 15.74 (mg/dL) for serum and CVGK. The ROC curve showed no sensitivity in detecting normoglycemic cows (area = 53.7 %, e.d = 12.5 %, p = 0.759) for CVGK when compared to plasma EPA (area = 36.1 %, e.d = 14.2 %, p = 0.256). Plasma EPA exhibited a better but not significant effect in detecting hyperglycemic cows (area = 63.9%, e.d = 14.2%, p = 0.256) when compared to HHD (area = 46.3 %, e.d = 12.5 %, p = 0.759). General glucose concentrations, independently of the method used, were significantly (p = <0.001) greater in young cows when compared to adult and old cows. (4) Conclusions: Glucose concentration measurement in plasma by using EPA or in capillary blood via CVGK were not reliable methods when compared with the reference method.

Non-Invasive Glucose Sensing Technologies and Products: A Comprehensive Review for Researchers and Clinicians.

Diabetes Mellitus incidence and its negative outcomes have dramatically increased worldwide and are expected to further increase in the future due to a combination of environmental and social factors. Several methods of measuring glucose concentration in various body compartments have been described in the literature over the years. Continuous advances in technology open the road to novel measuring methods and innovative measurement sites. The aim of this comprehensive review is to report all the methods and products for non-invasive glucose measurement described in the literature over the past five years that have been tested on both human subjects/samples and tissue models. A literature review was performed in the MDPI database, with 243 articles reviewed and 124 included in a narrative summary. Different comparisons of techniques focused on the mechanism of action, measurement site, and machine learning application, outlining the main advantages and disadvantages described/expected so far. This review represents a comprehensive guide for clinicians and industrial designers to sum the most recent results in non-invasive glucose sensing techniques' research and production to aid the progress in this promising field.

Proof of concept: stabilized whole blood material suitable for external quality assessment of near-patient testing devices

Abstract Objectives Even though reliable glucose concentration measurements are essential in diagnosis and monitoring of diabetes mellitus, external quality assurance based on mandatory reference method values can only be conducted to a limited extent for measurements in whole blood. The reason is the lack of stabilized whole blood materials suitable for the application in glucose measurement devices used in near-patient testing. Methods Two patented whole blood stabilizers were tested using four commercially available near-patient testing devices and one patient self-testing device for plasma-referenced glucose measurements. Furthermore, a laboratory method for plasma-glucose measurements was included. Venous whole blood samples from 30 apparently healthy volunteers were used. Two whole blood samples (stabilizer A and B) per subject were kept at room temperature over the study period of seven days and aliquots were taken each day from the original sample for measurement on all devices. After venous puncture, left over whole blood from the collection system was used for immediate glucose measurements without stabilizer on the near-patient testing devices. Results Each investigated device gave stable results at least for one of the two stabilizers for a period of four days. Imprecision based on quality controls ranged between 1.7 and 4.8 % coefficient of variation for near-patient testing devices, but did not reflect observed variability in measurement results from stabilized and unstabilized whole blood in one device. In addition, a considerable deviation of 0.8 mmol/L was observed among the near-patient testing devices underlining the need for reference method values in external quality control. Conclusions Our study provides proof of concept that for each investigated device at least one stabilizer of glucose in whole blood shows a good performance for at least four days. Therefore, these stabilizers appear to be suitable candidate materials for external quality assessment of near-patient testing devices.

Reliability of Handheld Blood Glucose Monitors in Neonates: Trustworthy Arterial Readings but Capillary Results Warrant Caution for Hypoglycemia.

Accurate glucose monitoring is vitally important in neonatal intensive care units (NICUs) and clinicians use blood glucose monitors (BGM), such as the Inform II, for bedside glucose monitoring. Studies on BGM use in neonates have demonstrated good reliability; however, most studies only included healthy-term neonates. Therefore, the applicability of results to the preterm and/or ill neonate is limited. In preterm and ill neonates, quantify differences in glucose concentrations between (1) capillary glucose (measured by BGM) and arterial glucose (measured by YSI 2300 Stat Plus) and (2) between aliquots from the same arterial blood sample, one measured by BGM versus one by YSI. Forty neonates were included in the study. Using Inform II, we measured glucose concentrations on blood samples simultaneously collected from capillary circulation via heel puncture and from arterial circulation via an umbilical catheter. Plasma was then separated from the remainder of the arterial whole blood sample and a YSI 2300 Stat Plus measured plasma glucose concentration. The dominant majority of arterial BGM results met the Clinical and Laboratory Standard Institute (CLSI) and Food and Drug Administration (FDA) tolerance criteria. Greater discrepancy was observed with capillary BGM values with an average of 27.5% of results falling outside tolerance criteria. Blood glucose monitor testing provided reliable results from arterial blood. However, users should interpret hypoglycemic results obtained from capillary blood with caution.

Monolithic integrated MQW-based optoelectronic glucose sensor.

This study presents the development process of a multi-quantum well (MQW)-based optoelectronic integrated device designed for precise glucose concentration measurements. The proposed monolithic device consists of two identical diodes containing InGaN/GaN MQWs, serving as a light emitter (LED) and a photodetector (PD), respectively. The chip is meticulously packaged with polydimethylsiloxane (PDMS) to facilitate exposure to the glucose solution. By monitoring changes in the photocurrent of the PD that detects scattered light of the LED propagating through the sapphire substrate, the chip can accurately reflect alterations in the glucose solution's concentration. The device's uniqueness lies in its ability to achieve this precision without the need for external optical components. The device exhibits a fast response, operating at a sub-second level, and can gauge glucose solutions with concentrations ranging from 5% to 40%. The fabricated optical sensing device showcases appealing characteristics, including compactness, stability, repeatability, and rapid response, making it highly suitable for glucose concentration measurement applications.

Generative adversarial networks‐based super‐resolution algorithm enables high signal‐to‐noise ratio spatial heterodyne Raman spectra

AbstractHigh‐resolution interference pattern images are vital for spatial heterodyne Raman spectroscopy to produce quality Raman spectra with a good signal‐to‐noise ratio. A sought‐after super‐resolution algorithm can enhance Raman interference pattern images, reducing reliance on expensive imaging sensors. This enables miniaturization and portability for point‐of‐care testing. This study proposes a generative adversarial network (GAN)‐based super‐resolution reconstruction algorithm explicitly designed for Raman interference patterns. Employing GAN adversarial training, the algorithm effectively reconstructs interference pattern images at higher resolution, improving Raman spectra signal‐to‐noise ratio. Considering Raman spectra analysis mainly focuses on characteristic peaks, a Raman characteristic peak‐focused network training scheme is used. For instance, acetaminophen is studied with two selected Raman characteristic peaks centered at 388 and 858 cm−1. These peaks are observed in Fourier transformed Raman spectra from corresponding low‐resolution interference pattern images obtained by down‐sampling high‐resolution ones by twofold and fourfold. The proposed GAN‐based algorithm successfully reconstructs low‐resolution interference patterns into high‐resolution ones, achieving high R‐square values (96.05% for twofold and 91.1% for fourfold). This innovation holds potential for point‐of‐care applications, like noninvasive blood glucose concentration measurements, enabling cost‐effective, portable Raman spectrometers with improved capabilities.

Helical Microfilament‐Electrode‐Based Semi‐Implantable Biosensors for In Vivo Electrochemical Detection

Semi‐implantable devices have shown potential for real‐time sensing of physiological information in vivo. For glucose detection in diabetes, semi‐implantable electrodes have the ability to measure glucose concentration directly from interstitial fluid (ISF) with high accuracy and continuous monitoring performance. However, electrochemical detection by the amperometric method is limited by the electrode size, which can restrict signal magnitude and sensitivity of the implantable microfilament electrode. To address this limitation, a semi‐implantable helical microfilament‐based glucose electrode (HMGE) is developed. The helical structure of the HMGE enhances the electrochemical sensing area, while the coating with carbon nanotube and poly(3,4‐ethylene‐dioxythiophene): polystyrene sulfonate provides an electron‐transfer interface for electrochemical sensing. The HMGE exhibits high selectivity and sensitivity for glucose detection. Through in vitro experiments, the sensitivity of HMGE is improved by about 7 times compared with that of the non‐helical structure. In in vivo studies in rats, it is demonstrated that HMGE system can continuously monitor glucose concentration changes in ISF with reasonable accuracy after signal calibrations. Furthermore, a circuit‐sensing system and smartphone application are developed to support the operation of HMGE system as a phenotype. The HMGE presents a promising semi‐implantable device for monitoring various electrolytes, metabolites, and biochemical signals in vivo.

Reverse iontophoresis generated by porous microneedles produces an electroosmotic flow for glucose determination

Blood glucose level is a key indicator of a patient's health, notably the symptoms associated with diabetes. Painless and continuously monitored interstitial glucose is highly preferable for diabetes management. Microneedle arrays can be used as an effective but minimally invasive technique to break the skin barrier. Simultaneous reverse iontophoresis enables non-invasive interstitial fluid extraction from the intercellular matrix ≤25 mm under the skin's surface. Here, we describe an ion-conductive porous microneedle (PMN)-based glucose sensing device combined with reverse ion electroosmosis, in which glucose extraction can be significantly enhanced. Four novel benefits of ionophoresis are concurrently brought about by the charged PMN: (1) decreased transdermal resistance with the low invasive penetration of highly resistant stratum corneum; (2) a reduction of transdermal resistance through interconnectivity; (3) the movement of larger molecules through linked micropores; and (4) the production of an electroosmotic flow (EOF). The EOF generated by PMN is effectively extracted from the skin interstitial fluid for glucose concentration measurement. And this will likely contribute to the long-term home management of chronic diseases.

Serum immunoglobulin concentration and the risk of type 2 diabetes mellitus in adults in Tianjin City: a prospective cohort study

Objective: To evaluate the association between immunoglobulin concentration and the risk of type 2 diabetes mellitus (T2DM) in adults in Tianjin City. Methods: Based on the Tianjin Chronic Low-grade Systemic Inflammation and Health (TCLSIHealth) cohort from January 2010 to December 2018, subjects who had completed the measurement of baseline immunoglobulin concentration and blood glucose concentration and not been diagnosed with any type of diabetes at baseline were selected in this study. The collected data included the concentration of serum immunoglobulin (IgG, IgM, IgA and IgE), fasting blood glucose and other potential confounders. The subjects were divided into four groups from Q1 to Q4 according to the quartiles of baseline immunoglobulin concentration. The multivariable Cox regression model was used to assess the association between the baseline immunoglobulin concentration and T2DM. Results: A total of 6 315 subjects aged (50.1±10.0) years were included. About 390 subjects were newly diagnosed with T2DM during the follow-up period. The incidence rate was 16.8/1 000 person-years. After adjusting for age, sex, waist circumference, smoking status, drinking status, eosinophil ratio, metabolic syndrome, first-or second-degree family history, and reciprocal adjusting for other immunoglobulin concentrations, compared to the lowest quartile concentration group Q1, subjects in group Q4 with the highest quartile of IgG concentration showed a lower risk of T2DM (HR=0.71, 95%CI: 0.52-0.97), and subjects in group Q4 with the highest quartile of IgM concentration also had a decreased risk of T2DM (HR=0.66, 95%CI: 0.47-0.91). Subjects in group Q4 with the highest quartile of IgA concentration had an increased risk of T2DM (HR=1.56, 95%CI: 1.18-2.07). The risk of T2DM decreased with the increase of serum IgG and IgM concentrations (Ptrend=0.018, Ptrend=0.010) and increased with the increase of serum IgA concentrations (Ptrend<0.001). No association was found between the concentration of IgE and T2DM risk (HR=0.99, 95%CI: 0.74-1.31, Ptrend=0.891). Conclusion: The concentration of IgG and IgM is negatively associated with the risk of T2DM, and the concentration of IgA is positively associated with the risk of T2DM in Tianjin City. The concentrations of IgG, IgM and IgA could be a predictor of hyperglycemia and T2DM.