Non-invasive glucose monitoring in patients with diabetes: A novel system based on impedance spectroscopy

• Published in: Biosensors & bioelectronics 2006-12, Vol.22 (5), p.598-604
• Main Authors: Caduff, A., Dewarrat, F., Talary, M., Stalder, G., Heinemann, L., Feldman, Yu
• Format: Article
• Language: English
• Subjects: Adult; Biological and medical sciences; Biosensing Techniques - instrumentation; Biosensing Techniques - methods; Biotechnology; Blood Glucose - analysis; Blood Glucose Self-Monitoring - instrumentation; Blood Glucose Self-Monitoring - methods; Diabetes; Diabetes Mellitus, Type 1 - blood; Diabetes Mellitus, Type 1 - metabolism; Electric Impedance; Electrochemistry - instrumentation; Electrochemistry - methods; Equipment Design; Equipment Failure Analysis; Female; Fundamental and applied biological sciences. Psychology; Glucose monitoring; Humans; Impedance spectroscopy; Male; Microelectrodes; Non-invasive; Reproducibility of Results; Sensitivity and Specificity; Spectrum Analysis - instrumentation; Spectrum Analysis - methods
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2006.01.031

The aim of this work was to evaluate the performance of a novel non-invasive continuous glucose-monitoring system based on impedance spectroscopy (IS) in patients with diabetes. Ten patients with type 1 diabetes (mean ± S.D., age 28 ± 8 years, BMI 24.2 ± 3.2 kg/m 2 and HbA 1C 7.3 ± 1.6%) and five with type 2 diabetes (age 61 ± 8 years, BMI 27.5 ± 3.2 kg/m 2 and HbA 1C 8.3 ± 1.8%) took part in this study, which comprised a glucose clamp experiment followed by a 7-day outpatient evaluation. The measurements obtained by the NI-CGMD and the reference blood glucose-measuring techniques were evaluated using retrospective data evaluation procedures. Under less controlled outpatient conditions a correlation coefficient of r = 0.640 and a standard error of prediction (SEP) of 45 mg dl −1 with a total of 590 paired glucose measurements was found (versus r = 0.926 and a SEP of 26 mg dl −1 under controlled conditions). Clark error grid analyses (EGA) showed 56% of all values in zone A, 37% in B and 7% in C–E. In conclusion, these results indicate that IS in the used technical setting allows retrospective, continuous and truly non-invasive glucose monitoring under defined conditions for patients with diabetes. Technical advances and developments are needed to expand on this concept to bring the results from the outpatient study closer to those in the experimental section of the study. Further studies will not only help to evaluate the performance and limitations of using such a technique for non non-invasive glucose monitoring but also help to verify technical extensions towards a IS-based concept that offers improved performance under real life operating conditions.