title: An artificial betacell: assessment of the glucose analyser, infusion system and optimization of constants for the algorithms.
abstract: The glucose analyser and insulin infusion modules of the Biostator were tested. The infusion system was reliable since more than 99% of the computed volume of insulin solution was delivered by the infusion pump at infusion rates above 1/100 of maximum, and no insulin was adsorbed onto infusion bags or tubing. Blood glucose results from the Biostator were compared with routine laboratory methods during long-term feedback control. Both slope (0.73) and scatter (r=0.87) around the regression line were unsatisfactory when the recommended calibration procedure was used. Tests in fasting non-diabetic subjects showed a significant correlation between the variation in Biostator glucose read-out and the plasma protein concentration in the detector outflow. In diabetics the ratio between Biostator glucose read-out and laboratory glucose determinations declined significantly with time. These observations led to the introduction of a standardization procedure based on externally determined blood glucose concentrations. During long-term feedback experiments in diabetics this procedure resulted in a significant increase in slope (0.84) but no improvement in scatter around the regression line. Repeated OGTTs revealed a set of constants for the algorithms, which enabled normal glucose tolerance to be achieved with smaller amounts of insulin.
mesh_terms: D000293:Adolescent; D000328:Adult; D001786:Blood Glucose / Q000032:analysis*; D003920:Diabetes Mellitus / Q000097:blood; D005069:Evaluation Studies as Topic; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D007332:Insulin Infusion Systems; D008433:Mathematics; D008875:Middle Aged; D012044:Regression Analysis; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D007328:Insulin