Noninvasive glucose monitoring - Comprehensive clinical results

Context Intensive diabetes management using frequent blood glucose measurem ents to guide therapy has been shown to significantly improve short- and lo ng-term outcomes. Development of a device that makes possible frequent, aut omatic, painless, and accurate measurements of glucose would facilitate int ensive management. Objective To determine the accuracy of the GlucoWatch automatic glucose bio grapher (Cygnus Inc) compared with that of serial blood glucose measurement s. Design Multicenter comparative study of the GlucoWatch biographer and the H emoCue blood glucose analyzer (Aktiebolaget Lee) performed between August 2 9 and October 17, 1998, Participants wore up to 2 biographers during the 15 -hour study session and performed 2 fingersticks per hour for comparative b lood glucose measurements, The biographers were calibrated with a single He moCue measurement after a 3-hour warm-up period, Diet and insulin were mani pulated to produce a broad glycemic range during the study. Setting Controlled clinical environment at 2 diabetes centers and 3 contrac t research organizations in the United States. Participants A total of 92 subjects (mean [SD] age, 42.1 [15.1] years; 59.8 % women) with type 1 or 2 diabetes requiring treatment with insulin. Main Outcome Measures Mean error, mean absolute error, correlation, slope, and intercept using Deming regression, and clinical significance of differe nces between biographer readings and blood glucose measurements using the C larke error grid. Results Results showed close tracking of blood glucose over a range of 2.2 to 22.2 mmol/L (40-400 mg/dL) for up to 12 hours using a single point calib ration. The biographer readings lagged behind serial blood glucose values b y a mean of 18 minutes. An analysis of 2167 data pairs shows a linear relat ionship (r = 0.88; slope = 1.03; intercept = -0.33 mmol/L [-6 mg/dL]) betwe en biographer readings and serial glucose measurements. The mean absolute e rror between the 2 measurements was 15.6% (mean error [SD], -0.07 [1.82] mm ol/L [-1 (33) mg/dL]), and 96.8% of the data fell in the therapeutically re levant regions of the error grid analysis. Conclusion These results demonstrate close agreement between GlucoWatch bio grapher readings and blood glucose measurements using repeated fingerstick blood samples. The automatic, frequent, and noninvasive measurements obtain ed with the biographer provides more information about glucose levels than the current standard of care.