Physiological Differences Between Interstitial Glucose and Blood Glucose Measured in Human Subjects
Physiological Differences Between Interstitial Glucose and Blood Glucose Measured in Human Subjects Eray Kulcu , MS 1 , Janet A. Tamada , PHD 1 , Gerard Reach , MD 2 , Russell O. Potts , PHD 1 and Matthew J. Lesho , PHD 1 1 Cygnus, Redwood City, California 2 INSERM U341, Diabetes Department, Hôtel-D...
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Published in | Diabetes care Vol. 26; no. 8; pp. 2405 - 2409 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Alexandria, VA
American Diabetes Association
01.08.2003
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Subjects | |
Online Access | Get full text |
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Summary: | Physiological Differences Between Interstitial Glucose and Blood Glucose Measured in Human Subjects
Eray Kulcu , MS 1 ,
Janet A. Tamada , PHD 1 ,
Gerard Reach , MD 2 ,
Russell O. Potts , PHD 1 and
Matthew J. Lesho , PHD 1
1 Cygnus, Redwood City, California
2 INSERM U341, Diabetes Department, Hôtel-Dieu Hospital, Paris, France
Address correspondence and reprint requests to Matthew J. Lesho, PhD, 400 Penobscot Dr., Redwood City, CA 94063. E-mail: mlesho{at}cygn.com
Abstract
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 ± 7.2 min for all subjects evaluated. The instrumental lag was 13.5 min, suggesting that physiological lag is ∼5 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.
BG, blood glucose
IG, interstitial glucose
IGS, interstitial glucose signal
NSI, normalized two-point sensitivity index
Ti, instrumental lag
Tp, physiological lag
Footnotes
A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.
E.K., J.A.T., and M.J.L. are employed by and hold stock in Cygnus, Inc. E.K. and R.O.P. were employed by Cygnus during the
research of this article and also hold Cygnus stock.
Accepted May 12, 2003.
Received January 30, 2003.
DIABETES CARE |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0149-5992 1935-5548 |
DOI: | 10.2337/diacare.26.8.2405 |