Estimation Of Glucose Levels Research Articles

Estimation of glucose levels in blood and saliva-a comparative study

Estimation of glucose levels in blood and saliva-a comparative study

Semantic representation and processing of hypoglycemic events derived from wearable sensor data

Diabetes Type 1 is a metabolic disease which results in a lack of insulin production, causing high glucose levels in the blood. It is crucial for diabetic patients to balance this glucose level, and they depend on external substances to do so. In order to keep this level under control, they usually need to resort to invasive glucose control methods, such as taking a sample drop of blood from their finger and have it analyzed. Recently, other directions emerged to offer alternative ways to estimate glucose level, using indirect sensor measurements including ECG monitoring and other physiological parameters. This paper showcases a framework for inferring semantically annotated glycemic events on the patient, which leverages data from mobile wearable sensors deployed on a sport-belt. This work is part of the D1namo project for non-invasive diabetes monitoring, and focuses on the representation and query processing of the data produced by the wearable sensors, using semantic technologies and vocabularies that extend existing Web standards. Furthermore, this work shows how different layers of data, from raw measurements to complex events can be represented and linked in this framework, and experimental evidence is provided of how these layers can be efficiently exploited using an RDF Stream Processing engine.

The upregulation of immune responses in tyrosine hydroxylase (TH) silenced Litopenaeus vannamei

Catecholamines (CAs) play a crucial role in maintaining physiological and immune homeostasis in invertebrates and vertebrates under stressful conditions. Tyrosine hydroxylase (TH) is the first and rate-limiting enzyme in CA synthesis. To develop an effective CA-related immunological defense system against stress and pathogen infection, various criteria, were evaluated in TH double-stranded (ds) RNA-injected white shrimp, Litopenaeus vannamei. Specifically, the relative transcript quantification of TH, dopamine β-hydroxylase (DBH), crustacean hyperglycemic hormone (CHH), and other immune-related genes; TH activity in the haemolymph; and the estimation of l-dihydroxyphenylalanine (l-DOPA), glucose, and lactate levels in the haemolymph were examined. TH depletion revealed a significant increase in the total haemocyte count; granular cells; semigranular cells; respiratory bursts (RBs, release of superoxide anion); superoxide dismutase (SOD) activity; phagocytic activity and clearance efficiency; and the expression of lipopolysaccharide and β-1,3-glucan-binding protein and peroxinectin, SOD, crustin, and lysozyme genes. In addition, the reduction of TH gene expression and activity was accompanied by a decline of phenoloxidase (PO) activity per granulocyte, lower glucose and lactate levels, and significantly low expression of DBH and CHH genes. However, the number of hyaline cells, activity of PO, RBs per haemocyte, and expression of POI and POII genes were not significantly different in the LvTH-silenced shrimp. Notably, the survival ratio of LvTH-silenced shrimp was significantly higher than that of shrimp injected with diethyl pyrocarbonate–water and nontargeting dsRNA when challenged with Vibrio alginolyticus. Therefore, the depletion of TH can enhance disease resistance in shrimp by upregulating specific immune parameters but downregulating the levels of carbohydrate metabolites.

Influence of curcumin on the pharmacodynamics and pharmacokinetics of gliclazide in animal models.

PurposePatients suffering from obesity-related diseases use multiple prescription drugs to control their condition, and it is therefore essential to determine the safety and efficacy of any combination. Gliclazide is one of the most commonly used drug of choice for treatment of type 2 diabetes, and curcumin is a widely used herbal supplement to counter obesity condition. The objective of this study was to investigate the effect of oral administration of curcumin on pharmacodynamics and pharmacokinetics of gliclazide in rats and rabbits to further evaluate the safety and effectiveness of this combination.MethodsInfluence of curcumin on the activity of gliclazide was determined by conducting single- and multiple-dose interaction studies in rats (normal and diabetic) and rabbits. Blood samples collected at predetermined time intervals from experimental animals were used for the estimation of glucose and insulin levels by using automated clinical chemistry analyzer and radioimmunoassay method, respectively. The insulin resistance and β-cell function were determined by homeostasis model assessment. Additionally, serum gliclazide levels in rabbits were analyzed by high-performance liquid chromatography.ResultsGliclazide showed peak reduction in blood glucose levels at 2 and 8 hours in rats and at 3 hours in rabbits. This activity of gliclazide was not altered by single-dose treatment with curcumin. However, in multiple-dose interaction studies, samples analyzed from all time points showed subtle but significantly greater reduction in percent blood glucose ranging from 23.38% to 42.36% in normal rats, 27.63% to 42.27% in diabetic rats, and 16.50% to 37.88% in rabbits. The pharmacokinetics of gliclazide was not altered by single- or multiple-dose curcumin treatments in rabbits.ConclusionThe interaction of curcumin with gliclazide up on multiple-dose treatment was pharmacodynamic in nature, indicating the need for periodic monitoring of glucose levels and dose adjustment as necessary when this combination is prescribed to obese patients.

Estimation of gingival crevicular blood glucose level for the screening of diabetes mellitus: A simple yet reliable method

AimThis study was designed to assess the reliability of blood glucose level estimation in gingival crevicular blood(GCB) for screening diabetes mellitus. Materials and method70 patients were included in study. A randomized, double-blind clinical trial was performed. Among these, 39 patients were diabetic (including 4 patients who were diagnosed during the study) and rest 31 patients were non-diabetic. GCB obtained during routine periodontal examination was analyzed by glucometer to know blood glucose level. The same patient underwent for finger stick blood (FSB) glucose level estimation with glucometer and venous blood (VB) glucose level with standardized laboratory method as per American Diabetes Association Guidelines.1 All the three blood glucose levels were compared. Periodontal parameters were also recorded including gingival index (GI) and probing pocket depth (PPD). ResultsA strong positive correlation (r) was observed between glucose levels of GCB with FSB and VB with the values of 0.986 and 0.972 in diabetic group and 0.820 and 0.721 in non-diabetic group. As well, the mean values of GI and PPD were more in diabetic group than non-diabetic group with the statistically significant difference (p<0.005). ConclusionGCB can be reliably used to measure the blood glucose level as the values were closest to glucose levels estimated by VB. The technique is safe, easy to perform and non-invasive to the patient and can increase the frequency of diagnosing diabetes during routine periodontal therapy.

Calibration of a microdialysis sensor and recursive glucose level estimation in ICU patients using Kalman and particle filtering

Abstract This paper deals with the estimation of glucose levels in ICU patients by the application of statistical filter theory to the data provided by a commercial continuous glucose monitoring system using a microdialysis sensor. Kalman and particle filtering are applied to simple models of the glucose dynamics. The particle filter enables the joint filtering and calibration of the sensor. The results show that the proposed filters lead to significant reduction in the estimation error with computational cost well within the capabilities of modern digital equipment. Additionally, the filters can be used for the automatic recognition of sensor faults. These results show that suitable filters can help in the construction of an artificial pancreas.

Continuous glucose monitoring in preterm infants: evaluation by a modified Clarke error grid.

BackgroundContinuous glucose monitoring using subcutaneous sensors has been validated in adults and children with diabetes, and was found to be useful in the management of glucose control. We aimed to assess feasibility and reliability of a new continuous glucose monitoring system (CGMS) in a population of preterm neonates using a Clarke error grid (CEG) specifically modified for preterm infants.MethodsPreterm infants were recruited within 24 h from delivery. A subcutaneous sensor connected to a CGMS was inserted and maintained for 6 days. Data collected from CGMS were compared with data obtained using a glucometer. Management of the infants followed standard protocols and was not influenced by CGMS readings.ResultsTwenty patients (9 males) were included. Median (range) gestational age was 32 weeks (27–36) and median (range) birth weight was 1350 g (860–3360). Average CGMS recording time was 137 h, for a total of 449 paired glucose levels. CEG and modified CEG criteria for clinical significance were met.ConclusionCGMS is a safe and clinically adequate method to estimate glucose levels in preterm infants. As the glucose level can be evaluated in real time, this CGMS could be useful to reduce the number of heel sticks, to observe glycaemic trends and to promptly detect episodes of both hypo- and hyper-glycaemia.

Correlation of the association of serum lactate, random blood sugar, and revised trauma score as predictors of outcome in hemodynamically unstable abdominal emergencies

Elevated levels of serum lactate and glucose during resuscitation have been demonstrated to be predictors of morbidity and mortality in hemodynamically unstable patients with surgical abdominal conditions. However, the rate of return to normal levels of both lactate and blood glucose may be better predictors of mortality and morbidity. The aims of this study are: (I) To determine the pattern of serum lactate and glucose changes in patients with surgical abdominal conditions requiring resuscitation within 48 hours of presentation. (II) To correlate the predictive capability of these two independent parameters. (III) To correlate the predictive values of these parameters with the revised trauma score (RTS). This is a prospective observational study conducted over three months. The patients admitted by the general surgery division requiring resuscitation from shock was included in this study. Resuscitation was carried out with crystalloids. The estimation of serum lactate and glucose levels was done at presentation (0 hours), 12, 24 and 48 hours after admission. The revised trauma score (RTS) was calculated for each patient at presentation and at 12, 24 and 48 hours subsequently. The patients were followed up four weeks or when death occurred within four weeks of presentation. Forty four patients were recruited in the study. There were seven mortalities. The mean serum levels of Plasma glucose and lactate of all the patients were elevated at presentation in the emergency department. Survival was better with a return to normal serum lactate within 12 hours. On the other hand the random plasma glucose (RPG) levels may not be useful in prognosticating patients. However a combination of serum lactate, RTS (at 24 and 48 hours) and RPG at 48 hours may improve predictive parameters in trauma related cases.

Estimation of Salivary Glucose levels as a Diagnostic aid for Diabetes Mellitus

Aim: The present study was designed to correlate the serum and salivary glucose levels and estimate associated salivary parameters (such as salivary flow rate, pH and buffering capacity) among diabetic and healthy individuals. Settings and Design: 80 patients were included in this study of which 30 patients were uncontrolled diabetics (group I), 30 patients were controlled diabetics (group II) and 20 patients were healthy individuals (group III). Materials and Methods: Salivary and serum glucose levels and salivary flow rate were measured using established methods. Results: The mean serum glucose was higher in group I as compared to group II and group III. In all the groups, salivary glucose levels significantly correlated with serum glucose levels. A statistically significant correlation was also observed between salivary glucose and salivary flow rate in all the three groups. The mean pH values were similar in all the three groups, indicating unaltered salivary buffering capacities. Conclusion: Salivary glucose levels may be used as an alternative and reliable index in diagnosis of diabetes mellitus.

Use of EZSCAN for detection of pre-diabetes and diabetes and comparison with standard screening methods

Objectives: Pre-diabetes is almost always a precursor to the development of type 2 diabetes. Comparison of EZSCAN with existing screening methods for detection of pre-diabetes and diabetes was done. Settings and Design: Cross sectional epidemiological study. Material and Methods: All cases underwent the EZSCAN test and had fasting plasma glucose (FBG), post-prandial plasma glucose (PPBG) and HbA1c level estimation. The results of EZSCAN were compared with fasting blood glucose, post-prandial blood glucose and HbA1c levels. Statistical analysis used: Mean, Standard deviation, sensitivity, specificity, positive and negative predictive value. Results: The sensitivity and specificity of EZSCAN when compared with FBG in diabetes was 87.2% and 87.2% respectively, for pre-diabetes 80.4% and 74.3% respectively and for non-diabetes 51.1% and 97.8% respectively. The sensitivity and specificity of EZSCAN when compared with PPBG in diabetes was 86.5% and 85.2% respectively, for pre-diabetes 76.9% and 72.6% respectively and for non-diabetes 52.8% and 98.9% respectively. The sensitivity and specificity of EZSCAN when compared with HbA1c in diabetes was 86% and 90.2% respectively, for pre-diabetes 87.8% and 71.4% respectively and for nondiabetes 46.3% and 98.8% respectively. Conclusions: EZSCAN proved to be a sensitive, specific, easy to perform screening test for diabetes and pre-diabetes which can be performed in non fasting state. EZSCAN is a simple device that can be operated by non medical personnel in non-healthcare settings with minimal subject preparation. Sri Lanka Journal of Diabetes, Endocrinology and Metabolism 2015; 5: 4-7

An Integrated Glucose Sensor with an All-Solid-State Sodium Ion-Selective Electrode for a Minimally Invasive Glucose Monitoring System

We developed a minimally invasive glucose monitoring system that uses a microneedle to permeate the skin surface and a small hydrogel to accumulate interstitial fluid glucose. The measurement of glucose and sodium ion levels in the hydrogel is required for estimating glucose levels in blood; therefore, we developed a small, enzyme-fixed glucose sensor with a high-selectivity, all-solid-state, sodium ion-selective electrode (ISE) integrated into its design. The glucose sensor immobilized glucose oxidase showed a good correlation between the glucose levels in the hydrogels and the reference glucose levels (r &gt; 0.99), and exhibited a good precision (coefficient of variation = 2.9%, 0.6 mg/dL). In the design of the sodium ISEs, we used the insertion material Na0.33MnO2 as the inner contact layer and DD16C5 exhibiting high Na+/K+ selectivity as the ionophore. The developed sodium ISE exhibited high selectivity (\( \log \,k^{pot}_{Na,K} = -2.8\)) and good potential stability. The sodium ISE could measure 0.4 mM (10−3.4 M) sodium ion levels in the hydrogels containing 268 mM (10−0.57 M) KCl. The small integrated sensor (ϕ &lt; 10 mm) detected glucose and sodium ions in hydrogels simultaneously within 1 min, and it exhibited sufficient performance for use as a minimally invasive glucose monitoring system.

PP.10.09

Objective: we exam 58 patients older 60 years (30 female, mean age 78 ± 0,4). We subdivided this patients in two groups: younger and older 80 years (n = 18). As a control group was patients younger 40 (third group) and patients in age 40–60 (4-th group). Design and method: For all patients we performed of estimation of lipid and glucose levels, echocardiography, 24-hour monitoring of blood pressure (BPLab device, «Petr Telegin», Russia). We estimated pulse wave velocity (PWV), augmentation index (Aix), index of arterial stiffness (ASI), ambulatory index rigidity (AASI). Statistic analyze we performed by «Biostat». Results: PWV in first group was in mean 9,3 ± 0,6 m/s, in second group 10,4 ± 0,5 m/s, in 3-d group 6,97 ± 0,04, in 4-th 8,2 ± 0,4 m/s; p3–1 < 0,05; p3–2 < 0,05. In first group PWV was more in male (10,75 ± 0,3 m/s; in female 8,71 ± 0,38, p < 0,05. In 2-d group PWV was in male 10,1 ± 0,4 m/s, in female 11,5 ± 0,2. In 31% of male and 65% of female older 80 years PWV was than 10 m/s. In patients in 4-th group we obtained more stronger increase PWV in male (8,7 ± 1,3 m/s in contrast in female 7,1 ± 1,3 m/s, p < 0,05). In patients younger 40 we do not obtained statistic differences between male and female. Progression of Aix in patients according to age was more stronger in female. Before 40 Aix in female was -26 ± 0,3% (in male -53,4 ± 0,7). In female in age 40–60 it was -21,3 ± 1,1% (in male -44,2 ± 0,1%). This tendency is preserved in 60–80 years in female -13,7 ± 1,4%, in male -22 ± 0,03, p < 0,05. In female older 80 it was 6,1 ± 0,8%, in male -5 ± 0,02%. According to age of patients we obtained tendency to impair of ASI, AASI. In patients younger 80 alteration of arteries were more stronger in male, after 80- in female. Conclusions: progression of increasing artery stiffness in patients older 60 inhomogeneous. In age 60–80 more strong progression was obtained in male: increasing of PWV, ASI, AASI. In female in this age Aix impair progression was more stronger. In patients older 80 years the most impaired of arterial stiffness was obtained in female. In this process was involved as direct as reflect pulse wave.

An Impedance and Multi-Wavelength Near-Infrared Spectroscopy IC for Non-Invasive Blood Glucose Estimation

A multi-modal spectroscopy IC combining impedance spectroscopy (IMPS) and multi-wavelength near-infrared spectroscopy (mNIRS) is proposed for high precision non-invasive glucose level estimation. A combination of IMPS and mNIRS can compensate for the glucose estimation error to improve its accuracy. The IMPS circuit measures dielectric characteristics of the tissue using the RLC resonant frequency and the resonant impedance to estimate the glucose level. To accurately find resonant frequency, a 2-step frequency sweep sinusoidal oscillator (FSSO) is proposed: 1) 8-level coarse frequency switching (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">STEP</sub> = 9.4 kHz) in 10-76 kHz, and 2) fine analog frequency sweep in the range of 18.9 kHz. During the frequency sweep, the adaptive gain control loop stabilizes the output voltage swing (400 mV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p-p</sub> ). To improve accuracy of mNIRS, three wavelengths, 850 nm, 950 nm, and 1,300 nm, are used. For highly accurate glucose estimation, the measurement data of the IMPS and mNIRS are combined by an artificial neural network (ANN) in external DSP. The proposed ANN method reduces the mean absolute relative difference to 8.3% from 15% of IMPS, and 15-20% of mNIRS in 80-180 mg/dL blood glucose level. The proposed multi-modal spectroscopy IC occupies 12.5 mm 2 in a 0.18 μm 1P6M CMOS technology and dissipates a peak power of 38 mW with the maximum radiant emitting power of 12.1 mW.

Antidiabetic Activity of Different Fractions of Ethanolic Extract of Dactyloctenium aegyptium in Streptozotocin Induced Diabetic Rats

Aims: The present study was aimed to evaluate the antidiabetic effect of n-hexane, Chloroform, Ethyl acetate and Methanolic fractions from ethanolic extract of Dactyloctenium aegyptium in streptozotocin induced diabetic rats. Study Design: The animals were divided into seven groups and each group consisted of six rats. Place and Duration of Study: Laboratory of Raghavendra Institute of Pharmaceutical Education&amp; Research (RIPER), Anantapuramu and 35 days.&nbsp;&nbsp; Methodology: The animals were divided into seven groups and each group consisted of six rats. Group I-Untreated normal rats, Group II-Untreated diabetic rats, Group III-Diabetic rats treated with Gliclazide 4.5 mg/kg, p.o. for 30 days, Group IV- Diabetic rats treated with n- hexane fraction of EDA (NHF) 50 mg/kg, p.o. for 30 days, Group V- Diabetic rats treated with Chloroform fraction of EDA (CF) 50 mg/kg, p.o. for 30 days, Group VI: Diabetic rats treated with Ethyl acetate fraction of EDA (EAF) 50 mg/kg, p.o. for 30 days, Group VII: Diabetic rats treated with Methanolic fraction of EDA (MF) 50 mg/kg, p.o. for 30 days and the serum was separated and used for the estimation of glucose levels. On 31st day of experiment, best fraction was investigated further for its action on insulin, Hb, HbA1c, oxidative parameters, body weight and cell integrity of pancreas. Results: Results indicated that animals treated with MF shown significant decrease in blood glucose, HbA1c, malondialdehyde levels and significant increase in insulin, Hb, SOD, catalase, reduced glutathione and body weight. Conclusion: It could be concluded that methanolic fraction of ethanolic extract of Dactyloctenium aegyptium has favourable effect in bringing down the severity of diabetes however necessary studies are required on characterization of active principles.

Estimation of glucose level and body weight in Alloxan Induced Diabetic Rat treated with Aqueous extract of Garcinia Kola Seed

Aim: Hypoglyceamic effect of Garcinia kola (GK) was evaluated in alloxan induced diabetic rats. Method: Eighteen male wistar albino rats of weights between 158-172g were divided into three groups A- C. Group A was given distilled water (D/W) throughout the experiment; diabetes was induced in group B and C. Group B was given d/w but not GK while group C was treated with GK extract for 21 days. Fasting blood samples were collected at baseline, 24 hours, 7th, 14th and 21st day for blood glucose evaluation. Results: Mean fasting blood glucose (FBG) level was significantly higher (P<0.001) after 24 hours diabetes induction with alloxan in groups B and C rats compared to the baseline. Group B showed geometric increase in FBG level and decrease in body weight from 24 hours after diabetes induction to the 21st day of study duration. Group C rats had significantly lower (P<0.001) mean FBG level than Group B rats. Significant difference in body weight was observed among the 3 groups throughout the study periods but for baseline. Conclusion: Treatment of alloxan induced diabetic rats with GK extract lowers blood glucose level and restores weight loss.

Assessment of leukocyte count as a cardiovascular risk marker in prediabetes

Background and Aim: Prediabetes is reported to be associated with the cardiovascular morbidity and mortality in Indian population. This study was conducted to screen out prediabetes (impaired fasting glycemia and impaired glucose tolerance [IGT]) and to assess white blood cell (WBC) counts as a risk factor for future cardiovascular complications. Methods: A total of 200 nondiabetic apparently healthy subjects were selected for the study. Estimation of plasma glucose (PG) levels by GOD-POD method and oral glucose tolerance test (GTT) was performed in all the subjects. Based on PG and GTT values, these subjects were divided into four groups, Group I: Normal fasting glucose/normal glucose tolerance (NFG/NGT, n = 70), Group II: Isolated Impaired fasting Glucose (iIFG, n = 34), Group III: Isolated IGT (iIGT, n = 38) and Group IV: Impaired fasting glucose and IGT (IFG/IGT, n = 54). WBC counts were estimated in all the subjects and were compared among the groups. Association of WBC with body mass index, systolic blood pressure (SBP), 2 hour post-challenge glucose levels (2 h PG) and rate pressure product was done using correlation analysis. Results: The iIGT and IFG/IGT group had a significantly higher WBC count compared to subjects with NFG/NGT and iIFG group ( P P > 0.05). WBC counts were significantly associated with rate pressure product in all prediabetic subjects and with SBP and 2 h PG in subjects with IGT. Bivariate regression analysis showed association of WBC with rate pressure product (RPP) a known cardiovascular risk factor in prediabetics after adjusting other parameters. Conclusion: This suggested that WBC count increase with raised 2 h PG in subjects with iIGT, and could be associated with metabolic syndrome and insulin resistance. Increased WBC counts and RPP in subjects with IGT, increases the cardiac risk burden in these subjects compared to subjects with IFG.

The potential impact of family history of loud Snoring and risk of Obstructive sleep apnea in overweight subjects.

Context: Central obesity, increased neck circumference are strong established risk factors of OSA. Familial aggregation is less explored potential risk factors. Aims: To compare sleep, metabolic parameters and risk of OSA in subjects with and without history of loud snoring in first degree blood relatives. Settings and Design: Cross-sectional tertiary hospitalbased study Methods and Material: Overweight subjects (body mass index >25 kg/m2 aged 18-65 yrs were selected using systematic random sampling from attendants of patients attending Pulmonary Medicine OPD. On the basis of inclusion and exclusion criteria,380 subjects were enrolled, inquired about “Loud snoring” in their first degree blood relatives and full night study, fasting serum lipid profile, plasma glucose level estimation was carried out after taking informed/written consent. Statistical analysis used: Statistical analysis was performed using SPSS 20. Student t test was applied for comparing mean values of various variables between two groups. Fisher test was applied for estimation of odd ratio (OR). Results: Neck circumference (p value .01), AHI value (p value .01) and fasting plasma glucose levels (p value .04) were found significantly higher in subjects with positive history of loud snoring in any first degree blood relative . Increased but insignificant risk (P value 0.15) of OSA (defined as AHI Conclusion: This study gives us a new direction for determining potential role of family history in near relatives in progression and occurrence of OSA in an individual. Key words: Familial aggregation, Obstructive Sleep Apnea , Obesity, snoring.

Noninvasive blood glucose sensing using near infra-red spectroscopy and artificial neural networks based on inverse delayed function model of neuron.

In this paper, a non-invasive blood glucose sensing system is presented using near infra-red(NIR) spectroscopy. The signal from the NIR optodes is processed using artificial neural networks (ANN) to estimate the glucose level in blood. In order to obtain accurate values of the synaptic weights of the ANN, inverse delayed (ID) function model of neuron has been used. The ANN model has been implemented on field programmable gate array (FPGA). Error in estimating glucose levels using ANN based on ID function model of neuron implemented on FPGA, came out to be 1.02 mg/dl using 15 hidden neurons in the hidden layer as against 5.48 mg/dl using ANN based on conventional neuron model.

Colorimetric estimation of human glucose level using γ-Fe2O3 nanoparticles: An easily recoverable effective mimic peroxidase

This article reports simple, green and efficient synthesis of γ-Fe2O3 nanoparticles (NPs) (maghemite) through single-source precursor approach for colorimetric estimation of human glucose level. The γ-Fe2O3 NPs, having cubic morphology with an average particle size of 30nm, exhibited effective peroxidase-like activity through the catalytic oxidation of peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2 producing a blue-colored solution. On the basis of this colored-reaction, we have developed a simple, cheap, highly sensitive and selective colorimetric method for estimation of glucose using γ-Fe2O3/TMB/glucose–glucose oxidase (GOx) system in the linear range from 1 to 80μM with detection limit of 0.21μM. The proposed glucose sensor displays faster response, good stability, reproducibility and anti-interference ability. Based on this simple reaction process, human blood and urine glucose level can be monitored conveniently.

Fractional frequency domain identification of NaCl–glucose solutions at physiological levels

Electrical impedance spectroscopy (EIS) has been used to characterize different biological materials. This article exposes a methodology oriented to estimate glucose levels of a solution based on a rational fractional parametric model of the impedance data. The methodology is applied over saline–glucose solutions at five physiological glucose levels, using three sensors and five repetitions for each glucose concentration and employed sensor. The results suggest that changes in the glucose concentration produce significant changes in the impedance that should be reflected in the parametric model. The modeling procedure shows that the poles and zeros of an integer model presents a degree of correlation. However, the correlation is clearly explicit employing fractional models where the mean location of the complex zeros is highly related to the glucose content in the sample.