Mensh Brett D, Wisniewski Natalie A, Neil Brian M, Burnett Daniel R
Theranova, LLC, San Francisco, CA 94107, USA.
J Diabetes Sci Technol. 2013 Jul 1;7(4):863-70. doi: 10.1177/193229681300700408.
Developing a round-the-clock artificial pancreas requires accurate and stable continuous glucose monitoring. The most widely used continuous glucose monitors (CGMs) are percutaneous, with the sensor residing in the interstitial space. Inaccuracies in percutaneous CGM readings during periods of lying on the devices (e.g., in various sleeping positions) have been anecdotally reported but not systematically studied.
In order to assess the impact of sleep and sleep position on CGM performance, we conducted a study in human subjects in which we measured the variability of interstitial CGM data at night as a function of sleeping position. Commercially available sensors were placed for 4 days in the abdominal subcutaneous tissue in healthy, nondiabetic volunteers (four sensors per person, two per side). Nocturnal sleeping position was determined from video recordings and correlated to sensor data.
We observed that, although the median of the four sensor readings was typically 70-110 mg/dl during sleep, individual sensors intermittently exhibited aberrant glucose readings (>25 mg/dl away from median) and that these aberrant readings were strongly correlated with subjects lying on the sensors. We expected and observed that most of these aberrant sleep-position-related CGM readings were sudden decreases in reported glucose values, presumably due to local blood-flow decreases caused by tissue compression. Curiously, in rare cases, the aberrant CGM readings were elevated values.
These findings highlight limitations in our understanding of interstitial fluid physiology in the subcutaneous space and have significant implications for the utilization of sensors in the construction of an artificial pancreas.
开发全天候人工胰腺需要准确且稳定的连续血糖监测。目前使用最广泛的连续血糖监测仪（CGM）是经皮的，其传感器位于组织间隙。有传闻报道了在躺在监测设备上时（例如，处于各种睡眠姿势）经皮CGM读数存在不准确的情况，但尚未进行系统研究。
为了评估睡眠和睡眠姿势对CGM性能的影响，我们在人体受试者中开展了一项研究，测量夜间组织间隙CGM数据的变异性与睡眠姿势的关系。将市售传感器放置在健康非糖尿病志愿者的腹部皮下组织中4天（每人四个传感器，两侧各两个）。通过视频记录确定夜间睡眠姿势，并将其与传感器数据相关联。
我们观察到，虽然睡眠期间四个传感器读数的中位数通常为70 - 110 mg/dl，但个别传感器会间歇性地出现异常血糖读数（与中位数相差>25 mg/dl），并且这些异常读数与受试者躺在传感器上密切相关。我们预期并观察到，大多数与睡眠姿势相关的异常CGM读数是报告的血糖值突然下降，可能是由于组织受压导致局部血流减少。奇怪的是，在极少数情况下，异常CGM读数是升高的值。
这些发现凸显了我们对皮下组织间隙液生理理解的局限性，并且对在构建人工胰腺中使用传感器具有重要意义。
