Panteleon Antonios E, Rebrin Kerstin, Steil Garry M
Medtronic MiniMed, Inc., Northridge, California, USA.
Diabetes Technol Ther. 2003;5(3):401-10. doi: 10.1089/152091503765691901.
In vivo subcutaneous glucose sensor accuracy depends on the calibration method. Sensor accuracy was assessed during standard oral glucose tolerance tests in six non-diabetic subjects each wearing six subcutaneous glucose sensors (Medtronic MiniMed). Paired blood glucose (B(G)) and sensor current readings were used for retrospective sensor calibration using either B(G) or sensor current as the independent variable. Sensor accuracy after calibration was assessed using three criteria: linear regression between B(G) and sensor glucose (S(G)); correlation; and mean absolute difference (MAD), defined as 100 x |B(G) - S(G)|/B(G). Calibration with B(G) as the independent variable resulted in unbiased estimates of regression slope (1.02, not different than 1, p< 0.01) and y-intercept (-1.06 mg/dL, not different than 0, p< 0.01). In contrast, calibration with sensor current as the independent variable resulted in biased estimates of slope (0.76, different than 1, p< 0.01) and y-intercept (31.25 mg/dL, different than 0, p< 0.01). However, with sensor current as the independent variable, the MAD was lower than the corresponding value for calibration with B(G) at the x-axis (15.00 +/- 0.47% vs. 18.35 +/- 0.63%, p< 0.01). The Pearson correlation coefficient between B(G) and S(G) was higher when using sensor current as the independent variable (R = 0.82 vs. R = 0.79 when using glucose on the x-axis). We suggest that despite the fact that calibration with sensor current as the independent variable leads to a bias in the estimate of B(G), it is a more appropriate calibration method when the primary concern is minimization of the MAD between S(G) and B(G).
体内皮下葡萄糖传感器的准确性取决于校准方法。在标准口服葡萄糖耐量试验期间，对六名非糖尿病受试者进行了传感器准确性评估，每名受试者佩戴六个皮下葡萄糖传感器（美敦力MiniMed）。使用配对血糖（B(G)）和传感器电流读数，以B(G)或传感器电流作为自变量进行回顾性传感器校准。校准后的传感器准确性通过三个标准进行评估：B(G)与传感器葡萄糖（S(G)）之间的线性回归；相关性；以及平均绝对差（MAD），定义为100×|B(G) - S(G)|/B(G)。以B(G)作为自变量进行校准，得到的回归斜率（1.02，与1无差异，p<0.01）和截距（-1.06mg/dL，与0无差异，p<0.01）估计无偏差。相比之下，以传感器电流作为自变量进行校准，得到的斜率（0.76，与1不同，p<0.01）和截距（31.25mg/dL，与0不同，p<0.01）估计有偏差。然而，以传感器电流作为自变量时，MAD低于在x轴上以B(G)进行校准时的相应值（15.00±0.47%对18.35±0.63%，p<0.01）。当使用传感器电流作为自变量时，B(G)与S(G)之间的Pearson相关系数更高（R = 0.82，而在x轴上使用葡萄糖时R = 0.79）。我们认为，尽管以传感器电流作为自变量进行校准会导致B(G)估计有偏差，但当主要关注点是最小化S(G)与B(G)之间的MAD时，它是一种更合适的校准方法。
