Monsod Teresa P, Flanagan Daniel E, Rife Fran, Saenz Rebecca, Caprio Sonia, Sherwin Robert S, Tamborlane William V
Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
Diabetes Care. 2002 May;25(5):889-93. doi: 10.2337/diacare.25.5.889.
The MiniMed Continuous Glucose Monitoring System (CGMS) measures subcutaneous interstitial glucose levels that are calibrated against three or more fingerstick glucose levels daily. The objective of the present study was to examine whether the relationship between plasma and interstitial fluid glucose is altered by changes in plasma glucose and insulin levels and how such alterations might influence CGMS performance.
Arterialized plasma glucose, sensor glucose, and interstitial fluid glucose were measured by microdialysis in 11 healthy subjects during a 1.0 mU. kg(-1). min(-1) stepped euglycemic-hypoglycemic-hyperglycemic (plasma glucose approximately 5, 3.1, and 8.6 mmol/l, respectively) insulin clamp that raised plasma insulin to approximately 360-390 pmol/l.
When the CGMS was calibrated versus plasma glucose levels before insulin infusion, basal sensor and plasma glucose were similar (5.0 +/- 0.3 vs. 5.2 +/- 0.3 mmol/l, respectively); dialysate glucose was 3.3 +/- 0.9 mmol/l. During the hyperinsulinemic-euglycemia study (plasma glucose 4.9 +/- 0.3 mmol/l), dialysate glucose fell by 30-35%, accompanied by a significant reduction in sensor glucose (to 3.7 +/- 0.6 mmol/l; P < 0.001 vs. plasma). Subsequently, sensor levels remained lower than plasma values during mild hypoglycemia (2.5 +/- 0.6 vs. 3.1 +/- 0.3 mmol/l; P < 0.01) and during recovery from hypoglycemia (7.3 +/- 1.2 vs. 8.6 +/- 0.6; P < 0.01). However, when the CGMS was calibrated against plasma glucose levels before and during each step of the clamp, sensor glucose levels increased throughout the study and did not differ from plasma glucose values during hypoglycemia.
Although hyperinsulinemia may contribute to modest discrepancies between plasma and sensor glucose levels, the CGMS is able to accurately track acute changes in plasma glucose when calibrated across a range of plasma glucose and insulin levels.
美敦力动态血糖监测系统（CGMS）通过每日与三个或更多指尖血糖水平进行校准来测量皮下组织间液葡萄糖水平。本研究的目的是探讨血浆葡萄糖和胰岛素水平的变化是否会改变血浆与组织间液葡萄糖之间的关系，以及这种改变如何影响CGMS的性能。
在11名健康受试者进行1.0 mU·kg⁻¹·min⁻¹的阶梯式血糖正常-低血糖-高血糖（血浆葡萄糖分别约为5、3.1和8.6 mmol/L）胰岛素钳夹试验期间，通过微透析测量动脉化血浆葡萄糖、传感器葡萄糖和组织间液葡萄糖，该试验使血浆胰岛素升高至约360 - 390 pmol/L。
当CGMS在胰岛素输注前根据血浆葡萄糖水平校准时，基础传感器葡萄糖和血浆葡萄糖相似（分别为5.0±0.3与5.2±0.3 mmol/L）；透析液葡萄糖为3.3±0.9 mmol/L。在高胰岛素血症-血糖正常研究期间（血浆葡萄糖4.9±0.3 mmol/L），透析液葡萄糖下降了30 - 35%，同时传感器葡萄糖显著降低（至3.7±0.6 mmol/L；与血浆相比，P<0.001）。随后，在轻度低血糖期间（2.5±0.6与3.1±0.3 mmol/L；P<0.01）以及从低血糖恢复期间（7.3±1.2与8.6±0.6；P<0.01），传感器水平仍低于血浆值。然而，当CGMS在钳夹试验的每个步骤之前和期间根据血浆葡萄糖水平进行校准时，整个研究过程中传感器葡萄糖水平升高，并且在低血糖期间与血浆葡萄糖值无差异。
尽管高胰岛素血症可能导致血浆与传感器葡萄糖水平之间存在适度差异，但当在一系列血浆葡萄糖和胰岛素水平上进行校准后，CGMS能够准确追踪血浆葡萄糖的急性变化。
