Glucose Concentration In Interstitial Fluid Research Articles

Analytical Performance of the FreeStyle Libre 2 Glucose Sensor in Healthy Male Adults.

Continuous Glucose Monitoring (CGM) not only can be used for glycemic control in chronic diseases (e.g., diabetes), but is increasingly being utilized by individuals and athletes to monitor fluctuations in training and everyday life. However, it is not clear how accurately CGM reflects plasma glucose concentration in a healthy population in the absence of chronic diseases. In an oral glucose tolerance test (OGTT) with forty-four healthy male subjects (25.5 ± 4.5 years), the interstitial fluid glucose (ISFG) concentration obtained by a CGM sensor was compared against finger-prick capillary plasma glucose (CPG) concentration at fasting baseline (T0) and 30 (T30), 60 (T60), 90 (T90), and 120 (T120) min post OGTT to investigate differences in measurement accuracy. The overall mean absolute relative difference (MARD) was 12.9% (95%-CI: 11.8-14.0%). Approximately 100% of the ISFG values were within zones A and B in the Consensus Error Grid, indicating clinical accuracy. A paired t-test revealed statistically significant differences between CPG and ISFG at all time points (T0: 97.3 mg/dL vs. 89.7 mg/dL, T30: 159.9 mg/dL vs. 144.3 mg/dL, T60: 134.8 mg/dL vs. 126.2 mg/dL, T90: 113.7 mg/dL vs. 99.3 mg/dL, and T120: 91.8 mg/dL vs. 82.6 mg/dL; p < 0.001) with medium to large effect sizes (d = 0.57-1.02) and with ISFG systematically under-reporting the reference system CPG. CGM sensors provide a convenient and reliable method for monitoring blood glucose in the everyday lives of healthy adults. Nonetheless, their use in clinical settings wherein implications are drawn from CGM readings should be handled carefully.

Performance of an interstitial glucose monitoring device in patients with type 1 diabetes during haemodialysis.

The use of interstitial glucose monitoring devices such as flash glucose monitoring has been shown to be beneficial in patients with type 1 diabetes mellitus (T1DM). However, these devices have been little studied in patients with diabetes treated by chronic haemodialysis (HD). The goal of this prospective, observational, multicentric study was to evaluate the analytical performance of the FreeStyle Libre 2 (FSL2) sensor in T1DM patients during HD sessions. During three HD sessions, interstitial fluid glucose (ISFG) concentrations given by the FSL2 were compared every 15minutes with blood glucose (BG) concentrations obtained simultaneously. BG concentrations were measured by two different glucometers: the Accu-Chek Guide and StatStrip meters. Twelve HD patients were included, with a mean age of 54±11years and a mean diabetes duration of 36.5±11.6years. Dialysis vintage was 35±22months. A total of 565 pairs of ISFG/BG values were available for analysis. The mean absolute relative difference, defined as the mean of the absolute relative differences between the ISFG and BG measurements, was 17.4% and 20.9% when the ISFG was compared with the StatStrip meter or Accu-Chek Guide, respectively. Interstitial results tend to underestimate blood results, but all values were classified as having clinically acceptable error. The differences observed remained stable during the dialysis session and were not associated with the ultrafiltration rate. Use of the FSL2 interstitial glucose monitoring device in HD patients with T1DM is clinically acceptable, even though the accuracy of the device is generally poorer than in studies including non-dialysis patients.

Continuous Monitoring of Interstitial Fluid Glucose Responses to Endurance Exercise with Different Levels of Carbohydrate Intake.

We compared the 24 h changes in interstitial fluid glucose concentration (IGC) following a simulated soccer match between subjects consuming a high-carbohydrate (HCHO; 8 g/kg BW/day) diet and those consuming a moderate-carbohydrate (MCHO; 4 g/kg BW/day) diet. Eight active healthy males participated in two different trials. The subjects were provided with the prescribed diets from days 1 to 3. On day 3, the subjects performed 90 min (2 bouts × 45 min) of exercise simulating a soccer match. The IGC of the upper arm was continuously monitored from days 1 to 4. No significant difference in the IGC was observed between trials during exercise. The total area under the curve (t-AUC) value during exercise did not significantly differ between the HCHO (9719 ± 305 mg/dL·90 min) and MCHO (9991 ± 140 mg/dL·90 min). Serum total ketone body and beta-hydroxybutyrate concentrations were significantly higher in the MCHO than in the HCHO after a second bout of exercise. No significant differences in the IGC were observed between trials at any time point during the night after exercise (0:00-7:00). In addition, t-AUC value during the night did not significantly differ between the HCHO (32,378 ± 873 mg/dL·420 min) and MCHO (31,749 ± 633 mg/dL·420 min). In conclusion, two days of consuming different carbohydrate intake levels did not significantly affect the IGC during a 90 min simulated soccer match. Moreover, the IGC during the night following the exercise did not significantly differ between the two trials despite the different carbohydrate intake levels (8 vs. 4 g/kg BW/day).

Effects Of Different Carbohydrate Intake Levels On Interstitial Fluid Glucose Concentration During High-intensity Intermittent Exercise

Effects Of Different Carbohydrate Intake Levels On Interstitial Fluid Glucose Concentration During High-intensity Intermittent Exercise

Microneedles coated with composites of phenylboronic acid-containing polymer and carbon nanotubes for glucose measurements in interstitial fluids

A microneedle (MN) sensor coated with a sensing composite material was proposed for measuring glucose concentrations in interstitial fluid (ISF). The sensing composite material was prepared by blending a polymer containing glucose-responsive phenylboronic acid (PBA) moieties (i.e., polystyrene-block-poly(acrylic acid-co-acrylamidophenylboronic acid)) with conductive carbon nanotubes (CNTs). The polymer exhibited reversible swelling behavior in response to glucose concentrations, which influenced the distribution of the embedded CNTs, resulting in sensitive variations in electrical percolation, even when coated onto a confined surface of the MN in the sensor. We varied the ratio of PBA moieties and the loading amount of CNTs in the sensing composite material of the MN sensor and tested them in vitro using an ISF-mimicking gel with physiological glucose concentrations to determine the optimal sensitivity conditions. When tested in animal models with varying blood glucose concentrations, the MN sensor coated with the selected sensing material exhibited a strong correlation between the measured electrical currents and blood glucose concentrations, showing accuracy comparable to that of a glucometer in clinical use.

Hand grip strength is inversely associated with total daily insulin dose requirement in patients with type 2 diabetes mellitus: a cross-sectional study.

Short-term (2 weeks to 3 months) insulin intensive therapy using continuous subcutaneous insulin infusion (CSII) can improve islet beta cell function and prolong glycemic remission in patients with newly diagnosed type 2 diabetes mellitus (T2DM). However, the total daily insulin dose (TDD, IU/kg/d) required to achieve near-normoglycemic control with CSII still needs to be frequently adjusted based on blood glucose monitoring. Although real-time continuous glucose monitoring (rtCGM), which measures the interstitial fluid glucose concentration continuously without much difficulty, facilitates the adjustment of insulin dosage, its adoption in the T2DM population is strictly limited by insurance coverage and lack of awareness of rtCGM among clinicians. Thus, it is of clinical significance to identify easy-to-use parameters that may allow a more rapid and accurate prediction of TDD requirement. This study aimed to explore the association between hand grip strength (HGS) and TDD requirement in patients with T2DM receiving CSII therapy. A total of 180 eligible patients with T2DM were enrolled in the study and divided into three groups based on their HGS: low (L), medium (M), and high (H). The TDD requirement was calculated on day 7 or 8 of CSII treatment. Anthropometric parameters, including HGS, skeletal muscle mass, skeletal muscle index (SMI) and 6-m gait speed, and laboratory data, were collected on the morning of the second day after admission, within the first 24 h of CSII therapy. These parameters were used to identify significant predictors of TDD requirement using Pearson or Spearman correlation test, and stepwise multiple regression analysis. There were no significant differences in age, duration of T2DM, waist-to-hip ratio (WHR), body mass index (BMI), blood pressure, liver function, estimated glomerular filtration rate, triglyceride, total cholesterol, glycosylated hemoglobin A1c (HbA1c), homeostatic model assessment of insulin resistance (HOMA-IR), and homeostasis model assessment of beta cell function (HOMA-β) among the groups. The H group had higher body muscle mass-to-fat ratio (BMFR), skeletal muscle mass-to-fat ratio (SMFR), SMI, 6-m gait speed, and lower TDD requirement than the M and L groups. The HGS negatively correlated with TDD requirement (r = -0.33, p < 0.001) after adjusting for sex, age, BMI, WHR, HbA1c, Ln (HOMA-β), Ln (HOMA-IR), Ln (BMFR), Ln (SMFR), SMI, and 6-m gait speed. Multivariate stepwise regression analysis indicated that HGS was an independent predictor of TDD requirement in patients with T2DM (β = -0.45, p < 0 001). Lower HGS is associated with an increased TDD requirement in T2DM patients. HGS may facilitate the prediction of TDD requirement in T2DM patients receiving CSII therapy.

An oxygen-insensitive and minimally invasive polymeric microneedle sensor for continuous and wide-range transdermal glucose monitoring

Despite significant advances in diabetes management, particularly with the introduction of the most recent continuous glucose monitoring devices (CGMDs) that can monitor glucose actively in the transdermal interstitial fluid (ISF) in vivo, CGMDs still have significant disadvantages in terms of accuracy, low interference effect, precision, and stability. This is mostly because they detect hydrogen peroxide at higher potentials and require an oxygen-rich environment. First in its class, we developed an oxygen-insensitive polymeric glucose microneedle (MN) that was functionalized using a new electron-transfer mediator, 3-(3′-phenylimino)-3H-phenothiazinesulfonic acid-based enzyme cocktail for the NAD-GDH system. The inclusion of reduced graphene oxide aided in the absorption of the cocktail via the π−π interaction and enhanced the conductivity and sensor performance. The MN exhibited a dynamic linear range (1–30 mM) with a low detection limit of 26 μM, high sensitivity (18.05 μAmM−1 cm−2), stability (up to 7 days), high selectivity (due to a low oxidation potential of 0.15 V), and a fast response time (∼3 s). In vivo, deployment of the MN in a rabbit model demonstrated that the ISF glucose concentrations measured with the MN for up to 24 h correlate very well with the blood glucose concentrations measured with a commercial glucometer.

Performance of the FreeStyle Libre Flash Glucose Monitoring System during an Oral Glucose Tolerance Test and Exercise in Healthy Adolescents.

This study's aim was to assess FreeStyle Libre Flash glucose monitoring (FGM) performance during an oral glucose tolerance test (OGTT) and treadmill exercise in healthy adolescents. This should advance the feasibility and utility of user-friendly technologies for metabolic assessments in adolescents. Seventeen healthy adolescents (nine girls aged 12.8 ± 0.9 years) performed an OGTT and submaximal and maximal treadmill exercise tests in a laboratory setting. The scanned interstitial fluid glucose concentration ([ISFG]) obtained by FGM was compared against finger-prick capillary plasma glucose concentration ([CPG]) at 0 (pre-OGTT), -15, -30, -60, -120 min post-OGTT, pre-, mid-, post- submaximal exercise, and pre- and post- maximal exercise. Overall mean absolute relative difference (MARD) was 13.1 ± 8.5%, and 68% (n = 113) of the paired glucose data met the ISO 15197:2013 criteria. For clinical accuracy, 84% and 16% of FGM readings were within zones A and B in the Consensus Error Grid (CEG), respectively, which met the ISO 15197:2013 criteria of having at least 99% of results within these zones. Scanned [ISFG] were statistically lower than [CPG] at 15 (-1.16 mmol∙L-1, p < 0.001) and 30 min (-0.74 mmol∙L-1, p = 0.041) post-OGTT. Yet, post-OGTT glycaemic responses assessed by total and incremental areas under the curve (AUCs) were not significantly different, with trivial to small effect sizes (p ≥ 0.084, d = 0.14-0.45). Further, [ISFGs] were not different from [CPGs] during submaximal and maximal exercise tests (interaction p ≥ 0.614). FGM can be a feasible alternative to reflect postprandial glycaemia (AUCs) in healthy adolescents who may not endure repeated finger pricks.

Differences in venous, capillary and interstitial glucose concentrations in individuals without diabetes after glucose load

Abstract Objectives Differences between capillary and venous glucose concentrations have been reported in the past. In continuous glucose monitoring (CGM) system performance studies, comparator measurements are often performed in venous samples, despite CGM systems typically aiming at providing capillary-like values. In this study, differences between venous, capillary and interstitial glucose concentrations, measured with a laboratory analyzer, a self-monitoring of blood glucose (SMBG) system and an intermittent-scanning CGM system were investigated in subjects without diabetes after glucose load. Methods During the study, an oral glucose tolerance test (oGTT) was performed with 41 participants who had no known history of diabetes (mean age 25.5 ± 9.7 years). Venous blood samples for measurement with a laboratory analyzer were collected before drinking the standardized 75 g glucose solution and after 60 and 120 min. In parallel, capillary blood was obtained for measurement with a laboratory analyzer and an SMBG system, and interstitial glucose values were measured with an intermittent-scanning CGM system. Results Glucose concentrations in the fasting state were slightly different for the three different compartments whereas considerable differences (some median differences exceeding 30 %) in glucose concentration were observed 60 and 120 min after the start of the oGTT. Conclusions Marked differences with a high inter-individual variability between venous, capillary, and interstitial fluid glucose concentrations were found especially after glucose load. These differences can affect perceived CGM accuracy in performance studies depending on the specific comparator method used, and they are potentially relevant in clinical practice, like diabetes diagnosis.

Glycemic profile and quality of recovery after emergency abdominal surgery-A prospective explorative cohort study.

Associations between degrees of postoperative hyperglycemia and morbidity has previously been established. There may be an association between the glycemic profile and patient-reported recovery, and this may be a target for perioperative quality improvements. We aimed to investigate the association between metrics of the 30-day glycemic profile and patient-reported recovery in nondiabetic patients after major abdominal surgery. In a prospective, explorative cohort study, nondiabetic adult patients undergoing acute, major abdominal surgery were included within 24 h after surgery. Interstitial fluid glucose concentration was measured for 30 consecutive days with a continuous glucose measurement device. The validated questionnaire 'Quality of Recovery-15' was used to assess patient-reported quality of recovery on postoperative days 10, 20, and 30. Follow-up time was divided into five-day postoperative intervals using days 26-30 as a reference. Linear mixed models were applied to investigate temporal changes in mean p-glucose, coefficient of variation, time within 70-140 mg/dl, and time above 200 mg/dl in relation to patient-reported recovery. Twenty-seven patients completed the study per protocol. A hyperglycemic event (>200 mg/dl) occurred in 18 of 27 patients (67%) within the first three postoperative days. Compared to the reference period, the coefficient of variation was significantly increased during all time intervals, indicating prolonged postoperative insulin resistance. During 30 days of follow-up, patient-reported recovery was associated with the coefficient of variation measured for 3 and 5 days before the corresponding recovery score assessment (recovery score estimate -1.52 [p< .001] and -0.92 [p= .006], respectively). We did not find an association between the remaining metrics and patient-reported recovery. Alterations in the glycemic profile are frequent and prolonged during the first postoperative month after major surgery probably due to peripheral insulin resistance. Our findings indicate that high-glycemic variation is associated with poorer patient-reported recovery and might represent a proxy for care improvements in the postoperative period.

Evaluation of HbA1c from CGM traces in an Indian population.

The development of continuous glucose monitoring (CGM) over the last decade has provided access to many consecutive glucose concentration measurements from patients. A standard method for estimating glycated hemoglobin (HbA1c), already established in the literature, is based on its relationship with the average blood glucose concentration (aBG). We showed that the estimates obtained using the standard method were not sufficiently reliable for an Indian population and suggested two new methods for estimating HbA1c. Two datasets providing a total of 128 CGM and their corresponding HbA1c levels were received from two centers: Health Centre, Savitribai Phule Pune University, Pune and Joshi Hospital, Pune, from patients already diagnosed with diabetes, non-diabetes, and pre-diabetes. We filtered 112 data-sufficient CGM traces, of which 80 traces were used to construct two models using linear regression. The first model estimates HbA1c directly from the average interstitial fluid glucose concentration (aISF) of the CGM trace and the second model proceeds in two steps: first, aISF is scaled to aBG, and then aBG is converted to HbA1c via the Nathan model. Our models were tested on the remaining 32 data- sufficient traces. We also provided 95% confidence and prediction intervals for HbA1c estimates. The direct model (first model) for estimating HbA1c was HbA1cmmol/mol = 0.319 × aISFmg/dL + 16.73 and the adapted Nathan model (second model) for estimating HbA1c is HbA1cmmol/dL = 0.38 × (1.17 × ISFmg/dL) - 5.60. Our results show that the new equations are likely to provide better estimates of HbA1c levels than the standard model at the population level, which is especially suited for clinical epidemiology in Indian populations.

Comparing the Rise in Glucose Concentration in Blood, Aqueous and Interstitial Fluid During a Glucose Tolerance Test.

The purpose of the study was to determine if aqueous glucose levels rise in a comparable time frame to interstitial fluid and could therefore be suitable for a continuous glucose monitoring (CGM) site. An intravenous glucose tolerance test was performed on five New Zealand white rabbits. Aqueous humor from the posterior and anterior chamber of the eye and venous blood were sampled for glucose concentration measurement. Glucose concentrations in the interstitial fluids were monitored using a CGM system. A compartment model was created to map the glucose response curves in each compartment. The delay in rising glucose concentrations between blood and interstitial fluid and aqueous humor in the posterior chamber and anterior chamber of the eye were analyzed. The results showed a statistically similar time lag and rate of change in glucose concentrations between blood and interstitial fluids or aqueous humor in either the posterior or anterior chamber. The results of this study add further support to the aqueous humor being used as an alternative CGM site. The study provides the basis for developing an intraocular continuous glucose sensor that can overcome limitations of current CGM systems.

A Week of Sleep Restriction Does Not Affect Nighttime Glucose Concentration in Healthy Adult Males When Slow-Wave Sleep Is Maintained

The aim of this laboratory-based study was to examine the effect of sleep restriction on glucose regulation during nighttime sleep. Healthy males were randomly assigned to one of two conditions: 9 h in bed (n = 23, age = 24.0 year) or 5 h in bed (n = 18, age = 21.9 year). Participants had a baseline night with 9 h in bed (23:00–08:00 h), then seven nights of 9 h (23:00–08:00 h) or 5 h (03:00–08:00 h) in bed. Participants were mostly seated during the daytime but had three bouts of treadmill walking (4 km·h−1 for 10 min) at ~14:40 h, ~17:40 h, and ~20:40 h each day. On the baseline night and night seven, glucose concentration in interstitial fluid was assessed by using continuous glucose monitors, and sleep was assessed by using polysomnography. On night seven, compared to the 9 h group, the 5 h group obtained less total sleep (292 min vs. 465 min) and less REM sleep (81 min vs. 118 min), but their slow-wave sleep did not differ (119 min vs. 120 min), and their glucose concentration during sleep did not differ (5.1 mmol·L−1 vs. 5.1 mmol·L−1). These data indicate that sleep restriction does not cause elevated levels of circulating glucose during nighttime sleep when slow-wave sleep is maintained. In the future, it will be important to determine whether increased insulin is required to maintain circulating glucose at a normal level when sleep is restricted.

Flap Monitoring Using Interstitial Fluid Glucose Measurements.

Background: Various flap monitoring techniques have been used in the early detection of anastomotic thrombus; however, the use of automatic and continuous monitoring methods is presently uncommon. The purpose of this study was to investigate trends in interstitial fluid glucose concentration (IFG) in flap monitoring by measuring IFG automatically and continuously. Methods: Nine patients underwent unilateral breast reconstruction using a transverse rectus abdominis myocutaneous flap with vascular anastomosis. Two IFG measuring devices were attached to each patient. One device was attached to the flap (flap IFG) and the other to the healthy breast (control IFG). In each case, flap IFG, control IFG, and IFG ratio (flap IFG/control IFG) were recorded in the initial 72 h post-surgery (first half) and also in the subsequent 72 h (second half). In all of the cases, the mean values recorded in the first half and those in the second half were compared. Results: All flaps survived. The flap IFG didn't fall below 40 mg/dL in the first half. The minimum flap IFG and IFG ratio were 42 mg/dL and 0.55 in the first half. The flap IFG was significantly higher in the first half than in the second half in all cases, and the IFG ratio was similar in 8 cases. Furthermore, mean flap IFG and mean IFG ratio in all cases in the first half were significantly higher than in the second half. Conclusions: IFG measurements may complement conventional flap monitoring, particularly in the early postoperative period.

Home-Based High-Intensity Interval Exercise Improves the Postprandial Glucose Response in Young Adults with Postprandial Hyperglycemia.

Postprandial hyperglycemia can be corrected by exercise; however, the effect of home-based high-intensity interval exercise (HIIE), a new time-efficient exercise, on glycemic control is unclear. This study aimed to investigate the effect of home-based HIIE on postprandial hyperglycemia. Twelve young adult males (mean age: 24.3 ± 2.3 y) with postprandial hyperglycemia that had not yet led to diabetes completed home-based HIIE, moderate-intensity continuous exercise (MICE), and control conditions on separate days, randomly. The intervention began 30 min after the start of a standardized meal intake, with 11 min of HIIE completed at maximal effort in the home-based HIIE condition, 30 min of running performed at 50% maximum oxygen uptake in the MICE condition, or 30 min of sitting at rest completed in the control condition. The participants sat at rest after each intervention for up to 120 min. Interstitial fluid glucose concentrations were measured using a continuous glucose monitoring system that scanned every 15 min for up to 2 h after the meal. The glucose concentrations after the meal were significantly lower in the home-based HIIE and MICE conditions than in the control condition (p < 0.001). There were no significant differences in the glucose concentrations between the home-based HIIE and MICE conditions. In conclusion, home-based HIIE was able to correct postprandial hyperglycemia.

One Bout of Resistance Training Does Not Enhance Metformin Actions in Prediabetic and Diabetic Individuals.

This study aimed to determine the separated and combined effects of metformin and resistance exercise on glycemic control, insulin sensitivity, and insulin-like growth factor 1 (IGF-1) in overweight/obese individuals with prediabetes and type 2 diabetes mellitus. Fourteen adults with a body mass index of 32.1 ± 4.1 kg·m-2, insulin resistance (HOMA-2 1.6 ± 0.6), and poor glycemic control (glycated hemoglobin, 6.9% ± 0.9%; 51.9 ± 10.7 mmol·mol-1) while taking metformin (1561 ± 470 g·d-1) were recruited. Participants underwent four 72-h long experimental trials in a randomized counterbalanced order, either 1) taking metformin (MET), 2) replacing metformin by placebo pills (PLAC), 3) taking placebo and undergoing a resistance training bout (RT + PLAC), and 4) taking metformin and undergoing the same RT bout (RT + MET). Interstitial fluid glucose concentration was frequently sampled to obtain 72-h glucose area under the curve (GAUC) and the percentage hyperglycemic glucose readings (>180 mg·dL-1; GPEAKS). Insulin sensitivity (i.e., HOMA-2) and IGF-1 were also assessed. HOMA-2 was not affected by treatments. GAUC and GPEAKS were similarly reduced below PLAC during RT + MET and MET (all P < 0.05). In contrast, RT + PLAC did not affect glucose concentration. Metformin decreased serum IGF-1 concentrations (P = 0.006), and RT did not reverse this reduction. A bout of full-body RT does not interfere or aid on metformin's blood glucose-lowering actions in individuals with prediabetes and type 2 diabetes mellitus.

72-LB: Clinical Evaluation of a Long-Term Optical Continuous Glucose Monitoring (CGM) System: Lumee Glucose

Profusa is developing a CGM System which tracks glucose concentrations in interstitial fluid for several months. It consists of a small hydrogel sensor (2.5 x 0.4 x 0.3 mm) that is permanently inserted by subcutaneous injection, and a wireless optical reader that is placed over the skin to measure the sensor’s fluorescent signal, which changes proportionally with glucose. We evaluated the sensor signal response compared to reference capillary blood glucose (BG) taken from a commercial glucose meter in seven subjects with type 1 and type 2 diabetes. Each subject received two sensor injections in the upper arm during the first visit, followed by multiple 6-hour ambulatory monitoring visits over a three-month period. Of the 14 sensors injected, 13 tracked glucose excursions during every monitoring visit up to 88 days. Applying retrospective calibration analysis to 106 sensor traces showed that 84% of the sensor traces had strong correlation with BG reference values, defined by r2 > 0.5. Parkes Error Grid Analysis revealed that of the paired sensor-reference values, 88.9% fell in zone A, 10.9% in zone B, and 0.2% in zone C (Figure 1). The Lumee Glucose System demonstrates glucose tracking functionality for a minimum of 3 months in subjects with type 1 and type 2 diabetes. Additional studies are ongoing to establish prospective calibration algorithms and to assess measurement timepoints beyond three months.View largeDownload slideView largeDownload slide DisclosureK. Q. Tran: None. C. Nguyen: Employee; Self; Profusa, Inc. H. T. Nguyen: Employee; Self; Profusa, Inc. S. J. Gamsey: Employee; Self; Profusa, Inc. C. G. Lepak: Employee; Self; Profusa, Inc. K. Rebrin: Employee; Self; Profusa, Inc.

Transdermal Electrochemical Monitoring of Glucose via High‐Density Silicon Microneedle Array Patch

AbstractCurrent technology for blood glucose level monitoring is mainly based on the invasive finger‐prick extraction of a small drop of blood using a lancet and measured via a handheld glucometer, which is not conducive to continuous measurements. Interstitial fluid (ISF) is gaining attention as an alternative biofluid. Its biochemical composition is very similar to that of blood and it can be monitored in a continuous manner via minimally invasive methods that cause no pain and minimize any risk of infection. Herein, a microneedle array (MNA) based transdermal sensing system for the pain free monitoring of ISF glucose is presented. High‐density silicon microneedles (≈9500 microneedles cm−2) are used to prepare a three‐electrode patch for the electrochemical monitoring of glucose. The MNA glucose patch shows very good selectivity when tested in artificial ISF, with a sensitivity of 0.1622 µA mm−1 cm−2 and a detection limit of 0.66 mm. In vivo application of the microneedle array in mice shows that the ISF glucose concentrations obtained with the MNA sensor gave very good correlation with the blood glucose levels determined with a commercial glucometer. This microneedle‐based sensing system hence provides an alternative transdermal diagnostic tool to the invasive existing techniques.

β-Lactoglobulin Elevates Insulin and Glucagon Concentrations Compared with Whey Protein-A Randomized Double-Blinded Crossover Trial in Patients with Type Two Diabetes Mellitus.

Whey protein is an insulinotropic fraction of dairy that reduces postprandial glucose levels in patients with type 2 diabetes mellitus (T2DM). We have recently shown that β-lactoglobulin (BLG), the largest protein fraction of whey, elevates insulin concentrations compared with iso-nitrogenous whey protein isolate (WPI) in healthy individuals. We therefore hypothesized that BLG pre-meals would lower glucose levels compared with WPI in patients with T2DM. We investigated 16 participants with T2DM using a randomized double-blinded cross-over design with two pre-meal interventions, (i) 25 g BLG and (ii) 25 g WPI prior to an oral glucose tolerance test (OGTT), followed by four days of continuous glucose monitoring (CGM) at home. BLG increased concentrations of insulin with 10%, glucagon with 20%, and glucose with 10% compared with WPI after the OGTT (all p < 0.05). Both BLG and WPI reduced the interstitial fluid (ISF) glucose concentrations (using CGM) with 2 mM and lowered glycemic variability with 10–15%, compared with tap-water (p < 0.05), and WPI lowered the ISF glucose with 0.5 mM compared with BLG from 120 min and onwards (p < 0.05). In conclusion, BLG pre-meals resulted in higher insulin, glucagon, and glucose concentrations compared with WPI in participants with T2DM. Pre-meal servings of WPI remains the most potent protein in terms of lowering postprandial glucose excursions.

Assessment of Glycometabolism Impairment and Glucose Variability Using Flash Glucose Monitoring System in Patients With Adrenal Diseases.

BackgroundThis study aimed to investigate the characteristics and extent of glycometabolism impairment in patients with adrenal diseases, including Cushing syndrome, primary aldosteronism, pheochromocytoma, and nonfunctional adrenal incidentaloma.MethodsThis study enrolled thirty-two patients with adrenal diseases as adrenal disease groups and eight healthy individuals as healthy controls. Blood glucose levels were indicated by glucose concentration in interstitial fluid, which was documented using flash glucose monitoring system. According to flash glucose monitoring system data, parameters representing general blood glucose alterations, within-day and day-to-day glucose variability, and glucose-target-rate were calculated. Furthermore, blood glucose levels at nocturnal, fasting, and postprandial periods were analyzed. Besides, islet β-cell function and insulin resistance were assessed.ResultsAnalysis of flash glucose monitoring system-related parameters indicated impaired glycometabolism in patients with adrenal diseases compared with that of healthy controls at general blood glucose, within-day and day-to-day glucose variability, and glucose-target-rate levels. Furthermore, the dynamic glucose monitoring data revealed that significantly affected blood glucose levels compared with that of healthy controls were observed at postprandial periods in the Cushing syndrome and primary aldosteronism groups; at nocturnal, fasting and postprandial periods in the pheochromocytoma group. Significant insulin resistance and abnormal β-cell function were observed in the Cushing syndrome group compared with that in healthy controls.ConclusionAdrenal diseases can negatively affect glucose metabolism. Patients diagnosed with adrenal diseases should receive timely and appropriate treatment to avoid adverse cardiovascular events linked to hyperglycemia and insulin resistance.