After 1 day of automatic adaptation by the bionic pancreas , the mean ( SD ) glucose level on continuous monitoring was lower than the mean level during the control period ( 13313 vs. 15930 mg per deciliter [ 7.40.7 vs. 8.81.7 mmol per liter ] , P < 0.001 ) and the percentage of time with a low glucose reading was lower ( 4.1 % vs. 7.3 % , P = 0.01 ) .