RAD, limits of agreement analysis, and Clarke error grid analysis between CGMS and CLD values in data sets at different time after CGMS sensor calibration and in different glycemic ranges.

Comparisons of RAD and bias were performed by unpaired t-test. Difference in percentage of matched points in Clarke error grid zone A was analyzed by χ2 test. RAD was calculated as absolute difference between time-matched CGMS and CLD value divided by CLD value, multiplied by 100. Bias was defined as the mean of the difference between time-matched CGMS and CLD values (CGMS minus CLD). Euglycemic level was defined as CLD serum glucose concentration of 3.9 to 10.0 mmol/L, and hyperglycemic level was defined as CLD serum glucose concentration greater than 10.0 mmol/L. Upper and lower limit of agreement were defined as bias±1.96 SD of the mean bias. CGMS = continuous glucose monitoring system. CLD = central laboratory device. RAD = relative absolute difference.