Hydrothermally grown ZnO nanorods were used for enzyme immobilization in glucose sensors. In particular, the surface area of the ZnO nanorods was tailored by the use of a seed layer and/or by changing the concentration of the precursors. The glucose sensing capability was found to be strongly associated with the surface area of the nanorods. The results clearly demonstrated that hydrothermally grown ZnO nanorods be successfully applied to the electrode system for the detection of glucose. In addition, the growth conditions also need to be carefully optimized in order to grow ZnO nanorods that are as slim and long as possible in order to maximize the surface area.