Effects of glucose in blood and skin impedance spectroscopy

Painless control of blood glycemic levels could improve life quality of diabetes patients, enabling a better regulation of hyper- and hypoglycaemia episodes and thereby avoiding physiological complications. The aim of this work is to investigate complex impedance detection of glucose levels in aqueous solutions, blood samples and non-invasive assays. Besides the results of such topology, baseline correction is also presented as an alternative to improve the system performance. First, D-glucose is analyzed with interdigital electrodes in aqueous solutions, showing correlations higher than 0.9 for phase and resistance components, both between 150 kHz and 650 kHz. Blood samples also confirm the importance of complex measurements in similar frequencies, with angle correlating 0.7 with glucose (150 kHz). Finally, skin impedance is obtained with tetrapolar electrodes, resulting in a maximal correlation of 0.62 for the same parameter and range as in blood. Analysis of the transcutaneous prediction with time indicates that the noninvasive precision of 16.47 mg/dL may reflect trends in arterial glucose changes faster than standard methods, appealing for the monitoring of all complex components of impedance.