A glucose monitoring system continuously measures the glucose concentration in a patient's blood, provides an indication of the rate of change of such concentration, and determines whether the measured concentration and rate of change are within certain preset limits. If not, an audible and/or visual alarm signal is generated. The glucose monitoring system includes a glucose sensor adapted to be inserted into the venous system of the patient, where it responds to blood glucose and produces sensor signals related to the glucose concentration. The sensor signals are delivered through a suitable interconnect cable to a glucose monitor. In one embodiment, the interconnect cable includes a contactless connector that electrically isolates the glucose sensor from the monitor, and reduces the number of conductors required to interface with a plurality of sensors. The glucose monitor interprets the sensor signals by applying a previously determined calibration to quantitatively determine the blood glucose value. The blood glucose value thus determined is then processed in order to determine the rate of change, is stored (to create a history or record), and may also be displayed in large, easy-to-read numerals. Rate of change information (trend) may also be numerically or graphically displayed.