Measurement Of Blood Glucose Concentration Research Articles

Real-time continuous glucose monitoring in preterm infants (REACT): an international, open-label, randomised controlled trial

SummaryBackgroundHyperglycaemia and hypoglycaemia are common in preterm infants and have been associated with increased risk of mortality and morbidity. Interventions to reduce risk associated with these exposures are particularly challenging due to the infrequent measurement of blood glucose concentrations, with the potential of causing more harm instead of improving outcomes for these infants. Continuous glucose monitoring (CGM) is widely used in adults and children with diabetes to improve glucose control, but has not been approved for use in neonates. The REACT trial aimed to evaluate the efficacy and safety of CGM in preterm infants requiring intensive care.MethodsThis international, open-label, randomised controlled trial was done in 13 neonatal intensive care units in the UK, Spain, and the Netherlands. Infants were included if they were within 24 h of birth, had a birthweight of 1200 g or less, had a gestational age up to 33 weeks plus 6 days, and had parental written informed consent. Infants were randomly assigned (1:1) to real-time CGM or standard care (with masked CGM for comparison) using a central web randomisation system, stratified by recruiting centre and gestational age (<26 or ≥26 weeks). The primary efficacy outcome was the proportion of time sensor glucose concentration was 2·6–10 mmol/L for the first week of life. Safety outcomes related to hypoglycaemia (glucose concentrations <2·6 mmol/L) in the first 7 days of life. All outcomes were assessed on the basis of intention to treat in the full analysis set with available data. The study is registered with the International Standard Randomised Control Trials Registry, ISRCTN12793535.FindingsBetween July 4, 2016, and Jan 27, 2019, 182 infants were enrolled, 180 of whom were randomly assigned (85 to real-time CGM, 95 to standard care). 70 infants in the real-time CGM intervention group and 85 in the standard care group had CGM data and were included in the primary analysis. Compared with infants in the standard care group, infants managed using CGM had more time in the 2·6–10 mmol/L glucose concentration target range (mean proportion of time 84% [SD 22] vs 94% [11]; adjusted mean difference 8·9% [95% CI 3·4–14·4]), equivalent to 13 h (95% CI 5–21). More infants in the standard care group were exposed to at least one episode of sensor glucose concentration of less than 2·6 mmol/L for more than 1 h than those in the intervention group (13 [15%] of 85 vs four [6%] of 70). There were no serious adverse events related to the use of the device or episodes of infection.InterpretationReal-time CGM can reduce exposure to prolonged or severe hyperglycaemia and hypoglycaemia. Further studies using CGM are required to determine optimal glucose targets, strategies to obtain them, and the potential effect on long-term health outcomes.FundingNational Institute for Health Research Efficacy and Mechanisms Evaluation Programme.

Silva KG, Rotta I, Costa LB, Sotomaior CS: Comparison of 2 portable human glucometers for the measurement of blood glucose concentration in White New Zealand rabbits. J Vet Diagn Invest 32(5): 683-688, 2020.

Silva KG, Rotta I, Costa LB, Sotomaior CS: Comparison of 2 portable human glucometers for the measurement of blood glucose concentration in White New Zealand rabbits. J Vet Diagn Invest 32(5): 683-688, 2020.

Non-Invasive Measurement of Glucose Concentration Using Red and Near-Infrared Light-Emitting Diodes

Many diabetic mellitus patients envision a non-invasive method of blood glucose measurement since they require periodic monitoring of their blood glucose levels to ensure that it is stable and within the normal range. In this study, we detected glucose concentration using commercial light emitting diodes (LEDs) with a wavelength of 700–1600 nm. Light of long wavelengths (e.g. NIR) infiltrate human skin and reach the blood vessel lining, thereby aiding in the non-invasive measurement of blood glucose concentration. To demonstrate this, the concentration of glucose solutions was measured using red and NIR-LEDs in a non-invasive manner. The sensitivity of glucose detection was greater when light of wavelength below 1000 nm was used, owing to the absorption of wavelengths above 1000 nm by water. Furthermore, we controlled the input current of the red and NIR-LEDs to confirm the light intensity deviation with increasing glucose concentrations and suggested the optimum wavelength of light using this in-vitro system. Among various LEDs, the 700 nm LED showed higher light intensity deviation with change in injection current compared to LEDs with the other wavelengths. In particular, compared to other LEDs, a stark difference was observed in the light intensity of the 700 nm LED while measuring glucose concentrations in the range of 50–100 mg/dl.

Outcome of glycemic control in critically ill patients receiving enteral formulas.

Stress hyperglycemia is a common condition in critically ill patients. Inappropriate nutritional supplementation may worsen blood glucose control in these patients. The present study aimed to investigate the outcome of blood glucose control status when using various enteral formulas. This retrospective study was conducted at the intensive care unit of a tertiary medical center in central Taiwan. Patients meeting the following inclusion criteria were enrolled in the study: age ≥20 years, respiratory failure requiring mechanical ventilation, and two consecutive blood glucose concentration measurements of ≥180 mg/dL. Demographic data, blood glucose samples, and hospital mortality were collected for analysis. A total of 4,604 blood glucose samples from 48 patients were analyzed. Results demonstrated no significant difference in mortality rate or blood glucose control between patients fed semi-elemental formulas and those fed polymer formulas. Serum HbA1C of <7.5% was a risk factor for hospital mortality (OR: 0.18, 95% CI: 0.04-0.89). Enteral formulas containing less carbohydrate were associated with better blood glucose control. No significant difference in the outcome of blood glucose control was observed between patients fed semi-elemental formula and those fed polymer formula. To achieve better blood glucose control in critically ill patients, formulas with lower carbohydrate content should be considered.

Theoretical Simulation of the Near-Field Probe for Non-Invasive Measurements on Planar Layers with Biological Characteristics.

The article presents the design of the near-field probe, which is a combined emitter (a combination of a symmetric dipole and an annular frame). The design of the probe allows forming a prolonged zone of the near-field. This effect can be used for in-depth penetration of the field in media with high absorption, without loss of information. Particular attention in this article is given to a detailed study of the interaction of the field created by this probe on plane-layered biological media. A theoretical analysis of the interaction of the electromagnetic field was carried out in a wide frequency band with a model plane-layer biological medium containing blood vessels of shallow depth using the proposed probe design. Conclusions are drawn about the depth of penetration of a useful signal into different media-analogs of biological tissue. This study is necessary to consider the possibility of using this probe for non-invasive measurements of blood glucose concentration. The studies were carried out using numerical simulation in the CST (Computer Simulation Technology) Microwave Studio environment. All biological tissues were simulated over a wide frequency range from 10 MHz to 10 GHz.

Evaluation of the clinical accuracy of six portable blood glucose meters in dogs

Portable blood glucose meters (PBGMs) are widely used because of their practicality. However, the accuracy of PBGMs has frequently been questioned. The objectives of this study were to evaluate factors that might interfere with measurements made using PBGMs, and to assess the clinical utility of 6 PBGMs. The glucose concentrations measured using the PBGMs were compared with those obtained using a reference method. The agreement between the measured values was assessed using Spearman correlation analysis, Passing-Bablok regression analysis, Bland-Altman plots, and consensus error grid analysis. Mann-Whitney and Kruskal-Wallis tests were performed to identify the parameters affecting glucose measurement. The results indicated that all of the PBGMs tested perform adequately for use in veterinary practice. In most cases, measurements made using PBGM corresponded well with the blood glucose values obtained using the reference method. Error grid analysis revealed that most of the PBGM values fell within zones A and B. However, some measurements of blood glucose concentrations < 80 mg/dL fell into zone C. PCV, and triglyceride and total protein concentration, significantly affected the output of some of the PBGMs. Therefore, clinicians should be aware of the characteristics of the PBGM that they use. Keywords: anemia, dogs, hematocrit, hypertriglyceridemia, hypoglycemia

Analysis and Design of a Microwave Coplanar Sensor for Non-Invasive Blood Glucose Measurements

In this paper a design for a microwave sensor for the non-invasive measurement of blood glucose concentrations is proposed. The sensor is intended for usage as part of a non-invasive glucose-quantifying device. With this aim, three different microwave resonator structures are analyzed as possible candidates, and strengths and weaknesses are highlighted in each case. The chosen resonator is an open structure in which a finger of the patient is placed, fulfilling the role of a sample to be characterized by the sensor. The shape and size of the finger thus condition those of the resonator. Variations in the concentration of blood glucose modify the dielectric properties of the tissue, which is part of the microwave resonator-finger system, and as such, the changes translate to the resonance frequency of the whole structure. Among the three studied topologies, it was found that a single resonator designed using a coplanar structure with a ground plane showed the best trade-off in frequency sensitivity, stability and repeatability of the measurements. A notable correlation, between the resonance frequency of the proposed sensor and the blood glucose levels measured with a traditional glucometer, was found. This highlights a potential interchangeability of both glucose measurement methods.

Investigation for correction formulas on the basis of packed cell volume for blood glucose concentration measurements obtained with portable glucometers when used in rabbits.

To determine effects of PCV on blood glucose (BG) concentration measurements obtained with a human portable blood glucometer (HPBG) and a veterinary portable blood glucometer (VPBG) on canine (cVPBG) and feline (fVPBG) settings (test methods) when used in rabbits and to develop correction formulas to mitigate effects of PCV on such measurements. 48 resuspended blood samples with known PVCs (range, 0% [plasma] to 92% [plasma and packed RBCs]) from 6 healthy research rabbits (experimental sample set) and 252 historic measurements of BG concentration and PCV in 84 client-owned rabbits evaluated at a veterinary hospital (validation data set). Duplicate measurements of BG concentration with each test method and of PCV were obtained for each sample in the experimental sample set, and the mean results for each variable for each test method and sample were compared with results from a clinical laboratory analyzer (reference method) used to determine the true BG concentration for each sample. Mean ± SD differences in measurements between the reference and test methods were calculated. Linear regression and modified Clarke error grid analysis were used to develop correction formulas for the test methods given known PCVs, and these formulas were evaluated on the validation data set with linear regression and a modified Clarke error grid. Blood glucose concentrations were falsely low for cVPBG and fVPBG used on samples with PCV < 31% and were falsely high for all test methods used on samples with PCV > 43%. Compared with original measurements, formula-corrected measurements overall had better agreement with reference method measurements for the experimental sample set; however, only the formula-corrected HPBG measurements had improved agreement for the validation data set. Findings indicated that, in rabbits, HPBG measurements had improved accuracy with the use of the correction formula HPBG measurement of BG concentration + ([0.75 × PCV] - 15); however, the correction formulas did not improve the accuracy of VPBG measurements, and we believe that neither the cVPBG nor fVPBG should be used in rabbits.

Beneficial role of Stevia rebaudiana dry extract on the blood glucose reduction in the chronic diabetes mellitus

Introduction: Prolonged hyperglycemia may lead to several detrimental microvascular or macrovascular complications in the chronic diabetes mellitus. Thus, achieving normal glycemic condition remains the most important strategy in the diabetes mellitus. Stevia rebaudiana plays an important role on the blood glucose reduction, however, its role in the chronic diabetes mellitus has not been fully elucidated yet.Method: Stevia rebaudiana dry extract (400 mg/kg BW) were given daily by oral gavage for 84 days in rat with diabetes. The measurement of blood glucose concentration were done monthly during the study. Urine output was analyzed on the day 1 and 84. Additionally, lipid profile were measured on the day 84.Results: Compared to the normal rat, significant hyperglycemia were observed in the diabetic rat. Blood glucose concentration tends to decrease in the rat received Stevia rebaudiana extract (St), however, significant difference was achieved on the day 84 of the study confronted to the diabetic rats. Moreover, lower concentration of plasma cholesterol concentration and urine output reduction was significantly observed in the St rat compared to the D rat on the day 84.Discussion: Daily intake of Stevia rebaudiana extract on its therapeutic doses may play beneficial role in the chronic diabetes mellitus by gradually reduced blood glucose concentration, urine output and plasma cholesterol concentration. However, further cellular analysis were required to explicate the exact mechanism.International Journal of Human and Health Sciences Vol. 05 No. 01 January’21 Page: 22-26

Syzygium polyanthum protects against diabetic cardiac apoptosis in the chronic diabetes mellitus

Introduction: Hyperglycemia has become the main characteristic of diabetes mellitus. Persistent hyperglycemia directly activates cell death pathway that plays pivotal role in the diabetic complication including diabetic cardiomyopathy. Syzygium polyanthum plays a beneficial role in the diabetic condition by reducing the blood glucose concentration, however the role of this natural resources in preventing further complication of diabetes mellitus has not been revealed fully yet.Method: Syzygium polyanthum dry extract (300 mg/kg body weight) were given daily for 28 days in the streptozotocin-induced diabetic rat. Measurement of blood glucose concentration were done three times during the study, meanwhile cholesterol concentration, myocardial diameter and cardiac apoptosis were measured on the day 28 of the study. Cardiac apoptosis was analyzed by the TdT-mediated dUTP nick end-labelling (TUNEL Assay).Results: Persistent hyperglycemia as well as cardiac apoptosis was significantly observed in the diabetic rat (D) on the day 28 of the study confronted to the normal rat (N). Interestingly, significant blood glucose reduction in concomitant with a lesser concentration of cardiac apoptosis were observed in the diabetic rat received 28 days Syzygium polyanthum extract (DS) confronted to the D rat. Additionally, lower plasma cholesterol concentration was significantly observed in the DS rat confronted to the D rat.Discussion: Significant cardiac apoptosis was observed in consistent with persistent hyperglycemia in the D rat as well as lesser cardiac apoptosis was observed in accordance with blood glucose concentration reduction in the DS rat. Therefore, Syzygium polyanthum may play beneficial role in the diabetic-associated cardiac apoptosis through its direct effect on the blood glucose concentration reduction. However further analysis should be done to fully elucidate the apoptotic pathway that involved.International Journal of Human and Health Sciences Vol. 05 No. 01 January’21 Page: 16-21

Blood Collection from The Porcine Ear Using a Jet Injector.

We present a new lancet-free method of capillary blood collection for the measurement of blood glucose concentration using a needle-free jet injector. This technique is tested on living animals and directly compared to the current best practice, lancet prick. Shallow jet injection into porcine outer-ear was performed using a portable needle-free jet injector with a slot-shaped nozzle. The jet injections presented used about 25 µL of injectate to penetrate porcine skin to about 1.4 mm, which is within the WHO standards for capillary blood sampling. The blood and fluid released by the jet injections and lancet pricks was collected. The volume and colour of these samples were analysed. The results demonstrate that jet injection is a feasible technique for the collection of capillary blood, despite the small volume of blood samples retrieved from all four pigs. Jet injection may be used in the future to retrieve capillary blood samples from human fingertips.

Evaluation of the Freestyle Optium Neo H point-of-care device for measuring blood glucose concentrations in sick calves.

BackgroundData on the performance of a glucometer in calves with different diseases are currently lacking.ObjectiveThe primary objective of this study was to evaluate the reliability of a point of care glucometer in calves affected by different diseases relative to a traditional bench‐top autoanalyzer.AnimalsOne hundred ninety‐six calves with different disorders in a referral hospital.MethodsProspective study. Venous blood samples were used for the determination of glucose concentrations in blood and plasma using the Freestyle Optium Neo H and autoanalyzer, respectively. Data were subjected to Passing‐Bablok regression and Bland‐Altman plots. The Freestyle Optium Neo H was the test method and the autoanalyzer was the reference method. The diagnostic performance of the glucometer relative to the autoanalyzer was assessed using 3 different plasma glucose concentrations.ResultsThe Passing‐Bablok regression for the glucometer against the reference method revealed the presence of both proportional bias (1.12; 95% confidence interval [CI], 1.07‐1.18) and constant bias (−11.25; 95% CI, −16.0 to −7.70). The glucometer yielded 92.2%‐100% sensitivity and 86.4%‐96% specificity for the assessing glucose concentration based on different concentration thresholds.Conclusions and Clinical ImportanceThe Freestyle Optium Neo H showed proportional and constant biases relative to the reference method. The glucometer showed poor performance according to criteria recommended by the International Standards Organization and the American Society for Veterinary Clinical Pathology. However, the glucometer determined hypoglycemia with high sensitivity and specificity therefore it might be used to diagnose hypoglycemia in calves with different diseases until calf‐specific POC glucometers are developed.

An Overview of Different Spectrophotometric Techniques for Non-Invasive Blood Glucose Measurement

Blood glucose concentration measurements are crucial to identify and monitor a condition called diabetes. The current methodologies in practice are invasive and can cause discomfort to patients due to frequent needle pricks. These pricks could also cause infection. Non-invasive methods for blood glucose measurement are a good alternative, if within an acceptable range of clinical accuracy. Non-invasive methodologies presently used for research are broadly classified as optical, thermal and electric. A sub-category of the optical method being: Spectrophotometry. The paper focuses on reviewing a few of the widely researched Spectrophotometric techniques for glucose measurement such as Near Infra-red, Raman and Fluorescence. The review aims at understanding the different spectrophotometric techniques and comparing them based on a few technical aspects such as selectivity, sensitivity and instrumentation required.

SPARC: Acute Glucose Regulation Recordings from the Rat Vagus Nerve Using Carbon Fiber Microelectrode Arrays

Glucose regulation is a vital continuous process for maintaining a healthy biological state. This requires complicated coordination between the endocrine and nervous systems. An important pathway in the peripheral nervous system for glucose regulation is the vagus nerve, as it innervates the liver and pancreas, which are the main organs for glucose regulation. However, limited information is available on the neural activity for glucose regulation that propagates through the vagus nerve. An electrode that has shown promising neural recording abilities with minimal tissue damage in the brain is the carbon fiber microelectrode array (CFMA). The objective of this study was to identify glucose regulation neural signals in the vagus nerve using CFMAs.In this study, we performed non‐survival experiments on anesthetized, fasted Sprague‐Dawley rats. Through a midline ventral cervical incision, the left vagus nerve was isolated and placed on a custom 3D‐printed nerve‐holder. A CFMA (10–16 fibers; 200–250 μm in length; 132 μm pitch; 2‐row layout) was inserted in the vagus nerve and connected to a neural interface processor that recorded at a sampling rate of 30 kHz. A bolus of glucose (1 g) or insulin (20 U) was administered intraperitoneally to modulate blood glucose levels, or saline (1 mL) for control. Measurements of blood glucose concentrations from the tail were obtained every 5 minutes using a glucometer. Neural data was analyzed using Plexon Offline Sorter and MATLAB.Glucose administration elevated blood glucose levels up to 114% above baseline. Observed neural units with firing rates up to 5 spikes/sec and peak‐to‐peak amplitudes of 31–43 μV decreased their firing rates after administration of glucose. These units may represent afferent signaling that were driven from fasting the animal, and the firing rates of these units decreased after glucose injection. Insulin administration decreased blood glucose levels by 34% from baseline. Approximately 2–5 minutes after insulin administration, units with amplitudes of 78–96 μV peak‐to‐peak were firing at rates up to 21 spikes/sec. These units may represent an increase in afferent activity to request glucose intake. In control experiments, observed units with amplitudes of 44–62 μV peak‐to‐peak maintained their firing rates of 5–9 spikes/s before and after administration of saline. These units may represent continuous afferent signaling to increase food intake or signaling that is not related to glucose regulation.Overall, our results demonstrate that CFMA is a viable electrode for recording neural unit activity related to glucose regulation in the vagus nerve. Furthermore, this work suggests that the CFMA can be used to monitor neural unit activity in peripheral nerves to help better understand the neural regulation pathways in various physiological and pathophysiological conditions.Support or Funding InformationThis research was supported by the National Institute of Health SPARC Program (Award OT2OD024907) and the National Science Foundation (Award 1707316).

In-Vivo and Ex-Vivo Measurements of Blood Glucose Using Whispering Gallery Modes.

The permittivity of blood glucose is not a strong function of its concentration in microwave or millimeter-wave frequencies. Measuring glucose concentrations remains a challenge, particularly in the presence of interference caused by the ambient leaky waves. In this paper, however, we demonstrate that a near-linear correlation between the glucose concentration and the blood permittivity was noticeably observed at a whispering gallery mode resonance. Method: the proposed sensor was a vacuum suction aspirator partially wounded with a turn of the Goubau line. This arrangement enabled a fixed cylindrical volume of a skin tissue bump or glucose/water solution to be formed and used as a whispering gallery resonator for in-vivo and ex-vivo measurements. Results: in the in-vivo study, a near-linear correlation between the glucose levels and the S21 parameters was noticeably observed at the fundamental whispering gallery resonance (i.e., at 2.18 GHz). In the ex-vivo study, a similar correlation was observed between the concentration of a glucose/water solution and the S21 parameters 56.6 GHz. Conclusion: the results of both investigations were consistent not only with the invasive measurements using the Accu-checkTM, but also with the conclusion drawn by some other research groups who have successfully measured blood glucose concentrations at millimeter-wave frequencies.

Effects of treatment with lispro and neutral protamine Hagedorn insulins on serum fructosamine and postprandial blood glucose concentrations in dogs with clinically well-controlled diabetes mellitus and postprandial hyperglycemia.

To assess effects of basal-bolus insulin treatment (BBIT) with lispro and neutral protamine Hagedorn (NPH) insulins, compared with NPH insulin alone, on serum fructosamine concentration (SFC) and postprandial blood glucose concentration (BGC) in dogs with clinically well-controlled diabetes mellitus and postprandial hyperglycemia fed a high insoluble fiber-content diet. 6 client-owned dogs with diabetes mellitus. Blood samples were collected for BGC and SFC measurement in hospitalized dogs just before feeding and routine SC NPH insulin administration (time 0); samples were collected for BGC measurement every 30 minutes for 2 hours, then every 2 hours for up to 10 additional hours. Postprandial hyperglycemia was identified when BGC 30 minutes after insulin administration exceeded BGC at time 0 or the 1-hour time point. For BBIT, owners were instructed to continue NPH insulin administration at the usual dosage at home (q 12 h, with feeding) and to administer lispro insulin (0.1 U/Kg, SC) separately at the time of NPH injections. Two weeks later, SFC and BGC measurements were repeated; results at the start and end of the study were compared statistically. Median SFC was significantly higher at the start (400 μmol/L) than at the end (390 μmol/L) of the study. Median 1-hour (313 mg/dL) and 1.5-hour (239 mg/dL) BGC measurements at the start of the study were significantly higher than those at the end of the study (117 and 94 mg/dL, respectively). In this sample of dogs with well-controlled diabetes mellitus, addition of lispro insulin to an existing treatment regimen of NPH insulin and dietary management significantly decreased postprandial BGCs. Further study of BBIT for dogs with diabetes mellitus is warranted.

Continuous Glucose Monitoring in Conscious Unrestrained Mice.

Measurement of blood glucose concentration is a common end point in studies using animal models of diabetes. Usually a blood glucose meter is used to measure non-fasted blood glucose concentrations, typically at frequencies of between 1 and 7 times per week. This process involves pricking the tip of the tail to collect a small blood sample (0.5-5μL), which could potentially cause a stress response and affect blood glucose concentrations. Moreover, with blood glucose concentrations constantly fluctuating in response to feeding and activity, a single-point measurement can easily misrepresent the actual glycemic control of the animal. In this chapter, we discuss the use of continuous glucose monitoring in mice by radio-telemetry which allows second-by-second changes in blood glucose to be captured without restraining the mouse. Glucose excursions rather than single-point measurements may prove more useful in detecting effects of treatments, and lack of handling may avoid stress responses causing artefacts. We outline what is involved in implanting such devices into mice including some practical tips to maximize success.

The relationship between plasma GIP and GLP-1 levels in individuals with normal and impaired glucose tolerance.

Glucose-dependent insulinotropic polypeptide (GIP) is released primarily from the proximal small intestine and glucagon-like peptide-1 (GLP-1) from the more distal small intestine and colon. Their relative importance to the incretin effect in health has been contentious in the past, although it now appears that GIP has the dominant role. It is uncertain whether there is a relationship between GIP and GLP-1 secretion. We aimed to evaluate the relationship between plasma GIP and GLP-1 responses to a 75-g oral glucose load in individuals with normal (NGT) and impaired glucose tolerance (IGT). One hundred healthy subjects had measurements of blood glucose, serum insulin, plasma GIP and GLP-1 concentrations for 240min after a 300mL drink containing 75g glucose. Fifty had NGT and 41 IGT; 9 had type 2 diabetes and were excluded from analysis. In both groups, there were increases in plasma GIP and GLP-1 following the glucose drink, with no difference in the magnitude of the responses between t = 0-240min. There was a weak relationship between the iAUC0-240min for GIP and GLP-1 in the combined (r = 0.23, P = 0.015) and in the IGT (r = 0.34, P = 0.01), but not in the NGT (r = 0.15, P = 0.14) group. There is a weak relationship between oral glucose-induced GIP and GLP-1 secretions in non-diabetic subjects.

Study of a noninvasive blood glucose detection model using the near-infrared light based on SA-NARX

Accumulated attempts have been made to develop models for near-infrared noninvasive measurement of human blood glucose concentration. Most of them focus on the relationship between near-infrared absorbance and blood glucose concentration, but do not consider the fluctuation regularity of blood glucose concentration and the influence of environmental factors and human physiological state on near-infrared absorption. In order to improve the performance of prediction model, a hybrid method is proposed in this paper. The nonlinear autoregressive model with exogenous input (NARX) was introduced as prediction model. 7 variables, including 1550 nm near-infrared absorbance, ambient temperature, ambient humidity, systolic pressure, diastolic pressure, pulse rate and body temperature were introduced as initial input variables. The sensitivity analysis (SA) method was employed to select the relative important input variables for NARX model. Based on the result of SA, a robust and accurate NARX model with 4 input variables (1550 nm near-infrared absorbance, systolic pressure, pulse rate and body temperature) was derived. Compared with the back propagation neural network (BPNN) with the same selected 4 input variables and the BPNN with initial 7 input variables, the NARX model developed there showed better prediction performance, of which the root mean square error and correlation coefficients were 0.72 mmol/L and 0.85 respectively for the 10-fold cross validation set. The percentages of the 10-fold cross validation set samples falling in region A and B of the Clarke error grid analysis were 90.27% and 9.73% respectively. These results demonstrate the potential of our model for noninvasive measurement of blood glucose concentration.

Effect of Spinal Anesthesia versus General Anesthesia on Blood Glucose Concentration in Patients Undergoing Elective Cesarean Section Surgery: A Prospective Comparative Study.

Background This prospective study compared the blood glucose concentration with spinal anesthesia or general anesthesia in patients undergoing elective cesarean section surgery. Methods In total, 58 pregnant women who underwent elective cesarean section surgery were included in this prospective comparative study. Group S (n = 35) included patients who chose spinal anesthesia, and group G (n = 23) included patients who chose general anesthesia. The patients were allocated to the groups upon patients' preference. For the group G, the blood glucose concentration (BGC) was obtained 5 minutes before induction, T1, and 5 minutes after induction T2. For the group S, the BGC was obtained immediately before the injection of the local anesthetic agent T1 and 5 minutes after the complete block T2. For both groups, BGC was measured 5 minutes before the end of surgery T3 and 30 minutes after the end of surgery T4. For BGC measurements, we used a blood glucose monitoring system with a lancet device to prick the finger. Results There was no statistically significant difference in the mean blood glucose concentration between the groups S and G in T1 (78.3 ± 18.2 vs. 74.3 ± 14.7, p > 0.05) and T2 (79.2 ± 18.3 vs. 84.9 ± 23.7, p > 0.05). The mean BGC was statistically significantly higher in group G in comparison to group S in the times 5 minutes before (80.2 ± 18.1 vs. 108.4 ± 16.7, p < 0.05) and 30 minutes after the end of surgery (80.9 ± 17.7 vs. 121.1 ± 17.4, p < 0.05). Conclusion There is a much lower increase in blood glucose concentration under spinal anesthesia than under general anesthesia. It is reasonable to suggest that the blood sugar concentration must be intraoperatively monitored in patients undergoing general anesthesia.