SUBCUTANEOUS GLUCOSE-CONCENTRATION IN HUMANS - REAL ESTIMATION AND CONTINUOUS MONITORING

OBJECTIVE - To determine the real subcutaneous glucose concentration i n healthy volunteers to help in the development of new calibration met hods for subcutaneous glucosensors. RESEARCH DESIGN AND METHODS - We d eveloped a new method to estimate the real subcutaneous glucose concen tration based on the recirculation of phosphate-buffered saline (PBS) in a microdialysis probe inserted into the subcutaneous tissue. Tissue glucose diffuses into the probe until complete equilibration between the glucose concentration outside and inside the microdialysis probe i s achieved. Later, the glucose content of the recirculated PBS is asse ssed in vitro. We applied the method in 10 healthy volunteers under fa sting state and during a hyperglycemic clamp. in addition, we monitore d the subcutaneous glucose with an enzymatic-amperometric glucosensor combined with a microdialysis probe. RESULTS - The subcutaneous glucos e concentration measured by the recirculation method was 72 +/- 6 and 78 +/- 6% of the blood glucose measured in the fasting state and durin g the hyperglycemic clamps, respectively. On the other hand, the gluco sensor's signal correlated significantly with the blood glucose. CONCL USION The recirculation method estimated the real subcutaneous glucose concentration, opening the way to develop new calibration procedures for subcutaneous glucosensors. However, a suitable calibration procedu re is still lacking.