The GlucoWatch<sup>®</sup>biographer: a frequent, automatic and noninvasive glucose monitor

Tierney, Michael J; Tamada, Janet A.; Potts, Russell O.; Eastman, Richard C.; Pitzer, Kenneth R.; Ackerman, Neil R.; Fermi, Steven J.

doi:10.3109/07853890009002034

Cited by 142 publications

(73 citation statements)

References 23 publications

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“…Reverse, transdermal iontophoresis has been proposed as an alternative technique for noninvasive monitoring (10)(11)(12)(13)(14)(15). Potential applications in clinical chemistry and therapeutic drug monitoring have been identified.…”

Section: Introductionmentioning

confidence: 99%

Reverse Iontophoresis as a Noninvasive Tool for Lithium Monitoring and Pharmacokinetic Profiling

et al. 2004

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Purpose. Transdermal iontophoresis was investigated as a noninvasive tool for drug monitoring and pharmacokinetic profiling. Lithium, a frequently monitored drug, was used as a model. The objectives were a) to demonstrate the linear dependence of the iontophoretic extraction flux of lithium on the subdermal concentration of the drug, b) to evaluate the capacity of iontophoresis to monitor sudden changes in the subdermal level, c) to investigate the utility of reverse iontophoresis as a tool in pharmacokinetic studies, and d) to examine the validity of an internal standard calibration procedure to render the method completely noninvasive. Methods. Transdermal, iontophoretic extraction was performed in vitro using dermatomed pig-ear skin. The subdermal solution consisted of a physiological buffer containing lithium chloride at concentrations in the therapeutic range and two putative internal standards, sodium and potassium, at fixed physiological levels. The subdermal concentration of lithium was changed either in a stepwise fashion or by simulating one of two pharmacokinetic profiles. Results. Lithium was extracted via electromigration to the cathode. A excellent correlation between subdermal lithium concentration and iontophoretic extraction flux was observed. Iontophoresis tracked sudden concentration changes and followed kinetic profiles. In addition, the effective elimination rate constant could be directly, and noninvasively, estimated from the extraction flux data. Conclusions. Reverse iontophoresis is a potentially useful and noninvasive tool for lithium monitoring.

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Section: Introductionmentioning

confidence: 99%

Reverse Iontophoresis as a Noninvasive Tool for Lithium Monitoring and Pharmacokinetic Profiling

et al. 2004

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“…We have evaluated the relationship between BG and glucose extracted from interstitial fluid using a GlucoWatch (Cygnus, Redwood City, CA) biographer. This is an Food and Drug Administrationapproved device used to detect trends and track patterns in glucose levels (3)(4)(5). It works through a process called reverse iontophoresis (6), which allows the biographer to collect glucose samples from subcutaneous interstitial space through intact skin by application of a low-level electric current.…”

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Physiological Differences Between Interstitial Glucose and Blood Glucose Measured in Human Subjects

et al. 2003

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OBJECTIVE -This study investigated whether glucose readings from a sensor sampling in interstitial fluid differ substantially from blood glucose (BG) values measured at the same time.RESEARCH DESIGN AND METHODS -We have evaluated the relationship between BG and glucose extracted from interstitial fluid using the GlucoWatch (Cygnus, Redwood City, CA) biographer, a device that collects glucose from subcutaneous interstitial space through intact skin by application of a low electric current. We evaluated the relative change in the interstitial glucose (IG) signal (IGS) as measured by the biographer versus BG using a normalized two-point sensitivity index (NSI).RESULTS -The results show that biographer measures of IG differ in time and magnitude from the corresponding BG values. In particular, the biographer values were shifted in time due to instrumental and physiological lag. Results show an average total lag of 17.2 Ϯ 7.2 min for all subjects evaluated. The instrumental lag was 13.5 min, suggesting that physiological lag is ϳ5 min. In addition, when glucose was increasing, the change in IGS was less than that in BG, while when BG was decreasing, the change in IGS was greater than that in BG.CONCLUSIONS -Similar results have been reported for other measures of IG, suggesting that differences reflect physiological variation in glucose uptake, utilization, and elimination in blood and interstitial space. This further evidence of the difference between IG and BG should be considered when interpreting glucose measurements from devices that sample interstitial fluid.

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“…The results presented here evaluate the hypoglycemia alert performance in a large and demographically diverse patient population using the biographer both in controlled and normal daily environments. The accuracy and precision results from these studies have been described (4).…”

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Detection of Hypoglycemia With the GlucoWatch Biographer

Pitzer

Desai²,

Dunn³

et al. 2001

Diabetes Care

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OBJECTIVE -Hypoglycemia is a common acute complication of diabetes therapy. The GlucoWatch biographer provides frequent and automatic glucose measurements with an adjustable low-glucose alarm. We have analyzed the performance of the biographer low-glucose alarm relative to hypoglycemia as defined by blood glucose Յ3.9 mmol/l. RESEARCH DESIGN AND METHODS -The analysis was based on 1,091 biographer uses from four clinical trials, which generated 14,487 paired (biographer and blood glucose) readings.RESULTS -The results show that as the low-glucose alert level of the biographer is increased, the number of true positive alerts (alarm sounds and blood glucose Յ3.9 mmol/l) and false positive alerts (alarm sounds but blood glucose Ͼ3.9 mmol/l) increased. When analyzed as a function of varying low-glucose alert levels, the results show receiver operator characteristic curves consistent with a highly useful diagnostic tool. Setting the alert level from 1.1 to 1.7 mmol/l above the level of concern is likely to optimize the trade-off between true positives and false positives for each user. When the same blood glucose data are analyzed for typical monitoring practices (two or four measurements per day), the results show that fewer hypoglycemic events are detected than those detected with the biographer.CONCLUSIONS -The frequent and automatic nature of the biographer readings allows more effective detection of hypoglycemia than that achieved with current medical practice. Diabetes Care 24:881-885, 2001H ypoglycemia is a common acute complication of diabetes therapy. The frequency of severe hypoglycemia has been shown to increase with more intensive treatment. Increasing the frequency of glucose measurements, regardless of the technique used, makes it possible to detect a greater number of hypoglycemic events. However, as many as seven glucose measurements per day may fail to detect hypoglycemic events (1).A device providing automatic readings could make frequent monitoring easier and enable an alarm to be sounded in response to glucose readings below userselected alert levels. Such an alarm could reduce the risk of hypoglycemia, making intensive therapy safer and more acceptable for patients. The GlucoWatch biographer (Cygnus, Redwood City, CA) provides frequent, automatic, and noninvasive glucose measurements-up to three readings per hour for as long as 12 h after a blood glucose measurement for calibration. Clinical studies in controlled and home environments have demonstrated high accuracy and precision (2,3). The results presented here evaluate the hypoglycemia alert performance in a large and demographically diverse patient population using the biographer both in controlled and normal daily environments. The accuracy and precision results from these studies have been described (4).The performance of the hypoglycemia alert depends on the selection of a low-glucose alert level that will trigger an audible alarm. The performance of the alert function can be best evaluated by an analysis of the receiver operator characteri...

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The GlucoWatch^®biographer: a frequent, automatic and noninvasive glucose monitor

Cited by 142 publications

References 23 publications

Reverse Iontophoresis as a Noninvasive Tool for Lithium Monitoring and Pharmacokinetic Profiling

Reverse Iontophoresis as a Noninvasive Tool for Lithium Monitoring and Pharmacokinetic Profiling

Physiological Differences Between Interstitial Glucose and Blood Glucose Measured in Human Subjects

Detection of Hypoglycemia With the GlucoWatch Biographer

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The GlucoWatch®biographer: a frequent, automatic and noninvasive glucose monitor

Cited by 142 publications

References 23 publications

Reverse Iontophoresis as a Noninvasive Tool for Lithium Monitoring and Pharmacokinetic Profiling

Reverse Iontophoresis as a Noninvasive Tool for Lithium Monitoring and Pharmacokinetic Profiling

Physiological Differences Between Interstitial Glucose and Blood Glucose Measured in Human Subjects

Detection of Hypoglycemia With the GlucoWatch Biographer

Contact Info

Product

Resources

About

The GlucoWatch^®biographer: a frequent, automatic and noninvasive glucose monitor