Original Article Influence of Time Point of Calibration on Accuracy of Continuous Glucose Monitoring in Individuals with Type 1 Diabetes

Background and Aims: Data on the influence of calibration on accuracy of continuous glucose monitoring (CGM) are scarce. The aim of the present study was to investigate whether the time point of calibration has an influence on sensor accuracy and whether this effect differs according to glycemic level. Subjects and Methods: Two CGM sensors were inserted simultaneously in the abdomen on either side of 20 individuals with type 1 diabetes. One sensor was calibrated predominantly using preprandial glucose (cali-brationPRE). The other sensor was calibrated predominantly using postprandial glucose (calibrationPOST). At minimum three additional glucose values per day were obtained for analysis of accuracy. Sensor readings were divided into four categories according to the glycemic range of the reference values (low, £ 4mmol/L; eu-glycemic, 4.1–7mmol/L; hyperglycemic I, 7.1–14mmol/L; and hyperglycemic II,> 14mmol/L). Results: The overall mean – SEM absolute relative difference (MARD) between capillary reference values and sensor readings was 18.3 – 0.8 % for calibrationPRE and 21.9 – 1.2 % for calibrationPOST (P < 0.001). MARD ac-cording to glycemic range was 47.4 – 6.5 % (low), 17.4 – 1.3 % (euglycemic), 15.0 – 0.8 % (hyperglycemic I), and 17.7 – 1.9 % (hyperglycemic II) for calibrationPRE and 67.5 – 9.5 % (low), 24.2 – 1.8 % (euglycemic), 15.5 – 0.9% (hyperglycemic I), and 15.3 – 1.9 % (hyperglycemic II) for calibrationPOST. In the low and euglycemic range