Microdialysis based monitoring of subcutaneous interstitial and venous blood glucose in Type 1 diabetic subjects by mid-infrared spectrometry for intensive insulin therapy

Abstract

Implementing strict glycemic control can reduce the risk of serious complications in both diabetic and critically ill patients. For this purpose, many different blood glucose monitoring techniques and insulin infusion strategies have been tested towards the realization of an artificial pancreas under closed loop control. In contrast to competing subcutaneously implanted electrochemical biosensors, microdialysis based systems for sampling body fluids from either the interstitial adipose tissue compartment or from venous blood have been developed, which allow an ex-vivo glucose monitoring by mid-infrared spectrometry. For the first option, a commercially available, subcutaneously inserted CMA 60 microdialysis catheter has been used routinely. The vascular body interface includes a double-lumen venous catheter in combination with whole blood dilution using a heparin solution. The diluted whole blood is transported to a flow-through dialysis cell, where the harvesting of analytes across the microdialysis membrane takes place at high recovery rates. The dialysate is continuously transported to the IR-sensor. Ex-vivo measurements were conducted on type-1 diabetic subjects lasting up to 28 hours. Experiments have shown excellent agreement between the sensor readout and the reference blood glucose concentration values. The simultaneous assessment of dialysis recovery rates renders a reliable quantification of whole blood concentrations of glucose and metabolites (urea, lactate etc) after taking blood dilution into account. Our results from transmission spectrometry indicate, that the developed bed-side device enables reliable long-term glucose monitoring with reagent- and calibration-free operation.