2型糖尿病患者频繁静脉取血法动态血糖监测的准确性评估

目的应用频繁静脉取血法在2型糖尿病患者中对回顾性动态血糖监测系统（CGMS）的点准确度及趋势准确度进行评价。方法2010年8月至10月共纳入11例2型糖尿病患者，应用美敦力公司GOLD^TM（GMS）连续监测3d血糖，同时每天输入4次指尖血糖值进行校正。受试者在CGMS监测的3d内随机选择1d参加连续7h的频繁静脉取血（15min取1次），并用美国YSI STAT Plus^TM葡萄糖乳酸分析仪（YSI值）进行血浆葡萄糖值的测定。应用多种统计方法和统计量来综合进行准确性评估，包括CGMS值和匹配的YSI值相比在20％和30％偏差范围内的一致率、误差栅格分析、绝对差值的相对数（ARD）、Bland—Ahman分析以及趋势分析等。两变量相关分析采用Pearson相关分析。结果11例患者共收集到319对YSI—CGMS配对数据值；与YSI值相比，88．4％（95％CI：0．84—0．92）的CGMS值在20％偏差范围内，96．9％的CGMS值在30％偏差范围内。Clarke误差栅格分析显示YSI—CGMS配对数据值进入A区和B区的比例分别为88％、12％，共识误差栅格分析显示进入A区和B区的比例分别为96．2％、3．8％。连续误差栅格分析显示YSI—CGMS配对数据值在准确数据区、良性错误区及错误数据区分别为94．4％、2．8％及2．8％。ARD的均值为10．5％，中位数为8．4％，Bland—Altman分析均值为0．47mmol/L（95％CI：-1．90-3．01）。趋势分析显示82．5％的两者变化率差异集中在0．06mmol·L^-1·min^-1的变化范围内，只有1．7％的数据对绝对差异超过0．17mmd·L^-1·min^-1。结论无论对点时血糖还是对血糖变化趋势的反映，CGMS均有较好的准确性；但对低血糖事件进行评判时，尚需结合临床实际情况具体分析。

Accuracy assessment of continuous glucose monitoring by frequent venous blood collection in patients with type 2 diabetes mellitus

Objective To assess the accuracy of continuous glucose monitoring system （CGMS） in type 2 diabetic patients by frequent venous blood collection. Methods A total of 11 patients with type 2 diabetes treated from August to October 2010 were enrolled in this study. The Medtronic GOLD^TM CGMS was used to monitor the continuous changes of the blood glucose levels for 3 successive days in all subjects, meanwhile the fingertip blood glucose was tested at least 4 times each day for calibration. The venous blood of the subjects was randomly collected every 15 min per hour for 7 successive hours on one day when the subjects wore the sensor, and was tested using the YSI 2300 STAT Plus^TM glucose＆lactate analyzer. The accuracy was comprehensively evaluated by using statistical methods including the rate of agreement between the sensor readings and the paired YSI values within ± 20% and ± 30% of deviations, the error grid analysis, absolute relative difference （ARD）, Bland-Altman analysis and trend analysis. Correlation analysis of two variables was done with Pearson correlation analysis. Results A total of 319 paired YSI-sensor values were collected from the 11 patients. Total 88.4% of the sensor readings （95% CI： O. 84 - 0. 92） were within ± 20% of the YSI values, and 96. 9% within ± 30% of the YSI values. Clarke error grid analyses showed that the ratios of the YSI-sensor values in region A to region B were 88% and 12% ; Consensus error grid analyses showed that the ratios of the YSI-sensor values in region A to region B were 96. 2% and 3.8% ; Continuous error grid analyses showed that the ratios of the YSI-sensor values in region of accurate reading, benign errors, erroneous reading were 94. 4%, 2. 8%, 2. 8%, respectively. The mean ARD for all subjects was 10. 5% and the median ARD was 8.4%. The Bland-Airman analysis detected the mean blood glucose level of 0.47 mmol/L （95% CI： - 1.90-3.01 mmol/L）. Trend analysis revealed that 82. 5% of the difference of the rates of change between the YSI values and sensor readings occurred within the range of 0.06 mmol · L^-l · min^-1, and only 1.7% of the absolute differences of the paired values were more than 0. 17 mmol · L^-1 · min^-1 Conclusions The CGMS has high accuracy both in monitoring the blood glucose at a specific time and reflecting the trend of changes of the blood glucose level. However, actual clinical manifestations should be taken into account for diaznosis of hvoozlvcemia.