Registration of dissolved glucose in vitro and in vivo by a combined microdialysis/amperometric method

Abstract

A device for continuous registration of dissolved glucose is obtained by combining the microdialysis technique with the measuring flow chamber of a glucose monitor using the glucose oxidase method for the determination of glucose concentration. In in vitro experiments, the glucose concentration measured in the microdialysis outlet is linearly related to the concentration of glucose standard solutions over a wide glucose concentration range up to 300 mg/dl. Under steady-state conditions, constant glucose signals from subcutaneously implanted microdialysis probes can be obtained in type-I diabetic persons for microdialysis perfusion flow rates at least up to 9 μl/min. For high perfusion flow rates (36 μl/min), a diluting effect of the subcutaneous tissue glucose content by the microdialysis system has to be assumed. When the device is tested kinetically in type-I diabetic persons under varying blood glucose levels, the time-lag between blood glucose concentrations varies interindividually for increasing and decreasing blood glucose levels. This may be due to the special nature of the microdialysis technique combined with varying degrees of tissue damage, when inserting the microdialysis probe, or to different compartment glucose exchange kinetics.