Several methods will be used to assess accuracy of the CGMS. The International Organization for Standardization (ISO) has put forth requirements for blood glucose monitoring systems. For reference values ≤75mg/dl sensor values should be within ±15mg/dl, and for reference values >75mg/dl sensor values should be within ±20%. We will initially determine the percentage of glucose pairs that meet these criteria. To determine the degree of agreement between sensor and reference the mean difference (MD, average of sensor values - reference values), mean relative difference (MRD, MD divided by the reference value multiplied by 100) will be calculated. The MD and MRD allow determination of a general under or overestimation by the sensor. The mean absolute difference (MAD, mean of the absolute value of: sensor value - reference value) will be calculated. The mean and median absolute relative difference (ARD, mean and median of the absolute value of: (sensor value - reference value) *100 / reference value) will also be calculated. These absolute differences provide insight into the overall accuracy of each individual meter reading. In the previous study in the medical intensive care unit 22 patients resulted in 546 glucose pairs for analysis. The calculated MAD was 19.7 with a standard deviation of 18.3. This resulted in a 95% confidence interval of [18.2-21.2]. In our study if we use a relatively conservative estimate of 45 patients studied for 1 day (24 hours) each with blood glucose measurements every 2 hours this results in 540 meter-sensor glucose pairs. Based on these data our study will result in a similarly narrow confidence interval for the MAD.