The determination of low concentration glucose is important with the development of noninvasive glucose monitoring technology. This paper describes a sensitive biosensor formed by the immobilization of Os-complex mediator and glucose oxidase on the electrode surface. Glucose biosensor exhibited analytic sensitivity of 28.24 nA mu M-1 cm(-2) at a low applied potential (0 mV vs. Ag vertical bar AgCl). Response to glucose proves to be linear with the correlation coefficient up to 0.999 in the relevant concentration range of 0-700 mu M. Relative standard deviations were 4.75% and 4.62% for within-run precision (n = 10) and between-run precision (n = 11). respectively. The limit of detection for glucose was 0.3 mu M. The biosensor exhibited sensitivity of 4.67 nA mM(-1) cm(-2) for subcutaneous glucose. The biosensor also indicates good stability of more than 90% of its original activity for about 15 months stored at 4 degrees C. The results show the biosensor is highly sensitive for the low concentration glucose, especially lot extracted subcutaneous glucose. (C) 2008 Elsevier B.V. All rights reserved.