Tissue implanted glucose needle electrodes: early sensor stabilisation and achievement of tissue-blood correlation during the run in period

Ahmed, Syed Thouheed; Dack, C.; Farace, G.; Rigby, G.; Vadgama, Pankaj

doi:10.1016/j.aca.2005.01.065

Cited by 17 publications

(9 citation statements)

References 21 publications

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“…The 10-h delay before the first calibration was instituted to allow time for the tissue around the sensor to achieve equilibrium after insertion. Variable delays in the time required for inserted sensors to achieve stable performance have been observed in many other systems (27)(28)(29). In contrast to other continuous glucose monitoring systems that are less accurate on the 1st day than the 2nd (10 -11), the 10-h delay in the FreeStyle Navigator system resulted in similar accuracy on the first 2 days as shown in Table 1.…”

Section: Clinical Accuracy Overallmentioning

confidence: 72%

Accuracy of the 5-Day FreeStyle Navigator Continuous Glucose Monitoring System

et al. 2007

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OBJECTIVE -The purpose of this study was to compare the accuracy of measurements of glucose in interstitial fluid made with the FreeStyle Navigator Continuous Glucose Monitoring System with Yellow Springs Instrument laboratory reference measurements of venous blood glucose.RESEARCH DESIGN AND METHODS -Fifty-eight subjects with type 1 diabetes, aged 18 -64 years, were enrolled in a multicenter, prospective, single-arm study. Each subject wore two sensors simultaneously, which were calibrated with capillary fingerstick measurements at 10, 12, 24, and 72 h after insertion. Measurements from the FreeStyle Navigator system were collected at 1-min intervals and compared with venous measurements taken once every 15 min for 50 h over the 5-day period of sensor wear in an in-patient clinical research center. Periods of high rates of change of glucose were induced by insulin and glucose challenges. RESULTS -Comparison of the FreeStyle Navigator measurements with the laboratory ref-erence method (n ϭ 20,362) gave mean and median absolute relative differences (ARDs) of 12.8 and 9.3%, respectively. The percentage in the clinically accurate Clarke error grid A zone was 81.7% and that in the in the benign error B zone was 16.7%. During low rates of change (ϽϮ1 mg ⅐ dl Ϫ1 ⅐ min Ϫ1 ), the percentage in the A zone was higher (84.9%) and the mean and median ARDs were lower (11.7 and 8.5%, respectively).CONCLUSIONS -Measurements with the FreeStyle Navigator system were found to be consistent and accurate compared with venous measurements made using a laboratory reference method over 5 days of sensor wear (82.5% in the A zone on day 1 and 80.9% on day 5).

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Section: Clinical Accuracy Overallmentioning

confidence: 72%

Accuracy of the 5-Day FreeStyle Navigator Continuous Glucose Monitoring System

et al. 2007

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“…4,5 Other concerns such as direct long-term integration with the host have not been completely solved. [6][7][8][9] The primary challenge affecting subcutaneous implanted glucose sensors as well as any implanted sensing device has been overcoming the host foreign body response while retaining proper function, e.g., resistance to signal drift and calibration maintenance. 10,11 The immense tissue-integration challenges associated with in vivo glucose measurements have precluded the long-term implantation (1−4 weeks) of glucose sensors for continuous glucose monitoring.…”

Section: Introductionmentioning

confidence: 99%

Microdialysis Sampling Extraction Efficiency of 2-Deoxyglucose: Role of Macrophages in Vitro and in Vivo

Mou

Stenken

2006

Anal. Chem.

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Macrophages are a class of inflammatory cells believed to direct the outcome of device biocompatibility. Despite their relevance to implanted in vivo devices, particularly implanted glucose sensors, few studies have attempted to elucidate how these cells affect device performance. Microdialysis sampling probes were used to determine glucose uptake alterations in the presence of resting and activated macrophages in vitro. Significant differences for 2-DG relative recovery at 1.0 μL/min were observed between resting (74 ± 7%, n=18) and lipopolysaccharide (LPS) (1 μg/mL) activated (56 ± 6%, n=18) macrophages in culture which had 2-DG spiked into the media (p<0.005). To establish if in vitro characterization could be correlated to in vivo studies, microdialysis probes were implanted into the dorsal subcutis of male Sprague-Dawley rats for 0,3,5 and 7 days. An internal standard, 2-deoxyglucose (2-DG), was passed through the microdialysis probe during in vivo studies. No significant differences in 2-DG extraction efficiency from the probe into the tissue site were observed in vivo among microdialysis probes implanted into the subcutaneous space of SpragueDawley rats for either three, five or seven days vs. probes implanted the day of sample collection. These results suggest that macrophage activation in vivo at implant sites is much lower than highly activated macrophages in vitro. It is important to note that these results do not rule out the potential for increased glucose metabolism at sensor implant sites.

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“…Because change in vascularization perturbs the balance between glucose supply and consumption, the trend has been toward design of sophisticated membranes, many of them modified polyurethanes. [316][317][318] Those maintained the desired glucose permeation characteristics and either were not encapsulated by tissue, or were overgrown with unchanging well-vascularized tissue, that is not glucose-depleted.…”

Section: Surgeon-implanted Long-term Glucose Monitorsmentioning

confidence: 99%

Electrochemical Glucose Sensors and Their Applications in Diabetes Management

2008

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About 6,000 peer reviewed articles have been published on electrochemical glucose assays and sensors, of which 700 were published in the 2005-2006 two-year period. Their number makes a full review of the literature, or even of the most recent advances, impossible. Nevertheless, this review should acquaint the reader with the fundamentals of the electrochemistry of glucose and provide a perspective of the evolution of the electrochemical glucose assays and monitors helping diabetic people, who constitute about 5% of the world's population. Because of the large number of diabetic people, no assay is performed more frequently than that of glucose. Most of these assays are electrochemical. The reader interested also in nonelectrochemical assays used in, or proposed for, the management of diabetes is referred to a 2007 review of Kondepati and Heise. 1 Adam Heller was born in 1933. Surviving the Holocaust, he arrived in Israel in 1945. He received his M.Sc. in Chemistry and Physics in 1957, then his PhD in Organic Chemistry in 1961 from Ernst David Bergman at the Hebrew University in Jerusalem. He postdoced at UC Berkeley (1962-3) and at Bell Laboratories . At GTE Labs (1964-1975 he built the first Nd 3+ liquid laser and, with J. J. Auborn, the still worldwide used Li/SOCl 2 battery. At Bell Labs (1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988) he designed the first >10% efficient electrochemical solar cells and the first >10% efficient hydrogengenerating solar-powered photoelectrode. He also headed Bell Labs' Electronic Materials Research Department (1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988), which developed part of the high density chip interconnection technology underlying the miniaturization of portable electronic devices. He was appointed to the Ernest Cockrell Sr. Chair in Engineering of the University of Texas at Austin in 1988, and in 2001 became one of UT's first Research Professors. At UT he pioneered the electrical wiring of enzymes. In 1996 he cofounded with his son Ephraim Heller TheraSense Inc., now part of Abbott Diabetes Care, to improve the lives of diabetic people. The company introduced in 2000 the blood sugar monitor FreeStyle, a thin-layer microcoulometer utilizing only 300 nL of blood, so little that it was, for the first time, painlessly obtained. In 2007 it provided for more than 1 billion painless glucose assays. After alleviating the pain of diabetes monitoring, FreeStyle Navigator, based on the electrical wiring of glucose oxidase, introduced in 2007 in Europe and Israel and in 2008 in the U.S., removed the worry of diabetic people by continuously monitoring their glucose levels. Heller aims his work at alleviating suffering through bioelectrochemistry.

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Tissue implanted glucose needle electrodes: early sensor stabilisation and achievement of tissue-blood correlation during the run in period

Cited by 17 publications

References 21 publications

Accuracy of the 5-Day FreeStyle Navigator Continuous Glucose Monitoring System

Accuracy of the 5-Day FreeStyle Navigator Continuous Glucose Monitoring System

Microdialysis Sampling Extraction Efficiency of 2-Deoxyglucose: Role of Macrophages in Vitro and in Vivo

Electrochemical Glucose Sensors and Their Applications in Diabetes Management

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