Clinical evaluation of the GlucoWatch (R) biographer: a continual, non-invasive glucose monitor for patients with diabetes

A device providing frequent, automatic, and non-invasive glucose measuremen ts for persons with diabetes has been developed: the GlucoWatch (R) biograp her. This device extracts glucose through intact skin via reverse iontophor esis where it is detected by an amperometric biosensor. The biographer can provide glucose readings every 20 min for 12 h. The performance of this dev ice was evaluated in two large clinical studies in a controlled clinical en vironment (n = 231), and the home environment (n = 124). Accuracy of the bi ographer was evaluated by comparing the automatic biographer readings to se rial finger-stick blood glucose (BG) measurements. Biographer performance w as comparable in both environments. Mean difference between biographer and finger-stick measurements was -0.01 and 0.26 mmol l(-1) for the clinical an d home environments, respectively. The mean absolute value of the relative difference was 1.06 and 1.18 mmol l(-1) for the same studies. Correlation c oefficient (r) between biographer and finger-stick measurements was 0.85 an d 0.80 for the two studies. In both studies, over 94% of the biographer rea dings were in the clinically acceptable A + B region of the Clarke Error Gr id. A slight positive bias is observed for the biographer readings at low B G levels. Biographer accuracy is relatively constant over all rates of BG c hanges, except when BG decreases more than 10 mmol l(-1) h(-1), which occur red for only 0.2% of points in the home environment study. Biographer preci sion, as measured by CV%, is approx. 10%. Skin irritation, characterized by erythema and edema, was either non-existent or mild in > 90% of subjects a nd resolved in virtually all subjects without treatment in several days. (C ) 2001 Elsevier Science B.V. All rights reserved.