In this paper, the design of a microwave based noninvasive glucose sensor at the operating frequency of 19 GHz is presented. Worldwide, about 451 million adults suffer from diabetes. For optimal therapy, people with diabetes should monitor their blood glucose level continuously over the day. For that purpose non-invasive microwave based glucose sensors are under research. Non-invasive microwave based glucose sensors must automatically perform continuous measurements with a high and stable accuracy. However, there exists no reliable noninvasive microwave based glucose sensor up to now. The proposed sensor is designed based on a two-port microstripline (MSL) network. Water with various glucose concentration from 0 to 500 mg/dl is placed in a slot between the two ports. The simulation results show that the phase change in the reflection coefficient for the various glucose concentration depends on the matching. The measurement of the glucose concentration 10 mg/dl can be realized by applying a taper ground plane as a matching technique decreasing reflections at the interface between the microstripline substrate and the water. The proposed sensor achieves a sensitivity of 2 ° phase change per 10 mg/dl glucose concentration variation. In the future, the simulation results should be validated in an experimental setup.