Continuous blood glucose analysis in vitro and in vivo

A practical method for continuous blood glucose analysis in vivo is described. Using an interference-free enzyme reagent in a modified Auto-Analyzer whole blood glucose concentration can be monitored continuously and interpreted in terms of the actual plasma glucose concentration. The method uses a novel technique for preheating the sample diluent without introducing additional time delays, consumes whole blood at a rate of 0.05 ml/min, and demonstrates a transport delay of 148 s. Other improvements include an average baseline drift of -0.11 mg/dl/h and a mean change in sensitivity of -0.4% after 8.5 h. In vitro glucose recovery studies comparing whole blood to the corresponding plasma samples show the method is precise (101.3 +/- 0.7%), linearly proportional (slope of 1.007 +/- 0.012) and highly correlated (greater than 0.998) over the range of 0 to 500 mg/dl, with reference to a Beckman glucose analyzer. In vivo applications are presented to show that this method is suitable for us in systems such as the 'artificial endocrine pancreas'.