Determination of Plasma Glucose During Rapid Glucose Excursions with a Subcutaneous Glucose Sensor

Abstract

Continuous glucose monitoring has the potential to improve glucose management and reduce the risk of hypoglycemia in individuals with diabetes. Accurate sensors may also allow the development of a closed-loop insulin delivery system. The purpose of this work was to determine the delay time associated with a subcutaneous glucose sensor during rapidly changing glucose excursions. Subcutaneous glucose sensors (Medtronic MiniMed, Inc., Northridge, CA) were inserted in five healthy men. After a 2-h stabilization period, a 3-h hyperglycemic (approximately 11 mM) clamp was performed followed by a 90-min period in which plasma glucose was allowed to decline to as low as 2.8 mM. Sensors were calibrated using two points (basal and hyperglycemia), and the calibrated sensor glucose measurements were compared with those from a reference analyzer (Beckman Instruments, Fullerton, CA). Response time was estimated from a first-order kinetic model. Plasma glucose levels, determined with the subcutaneous sensor, were highly correlated with those obtained with the reference glucose analyzer (r(2) = 0.91, p < 0.001; mean absolute difference of approximately 8%). The half-time for the sensor response was estimated to be 4.0 +/- 1.0 min. The subcutaneous glucose sensor has the potential to facilitate the detection of hypoglycemia and improve overall glycemic control when used in a real-time monitor. The rapid response should be sufficient to allow a fully automated closed-loop insulin delivery system to be developed based on the subcutaneous sensing site.

Interstitial fluid glucose dynamics during insulin-induced hypoglycaemia

“…This finding is in agreement with those from our previous hyperglycaemic clamp studies, which also showed no effect of insulin on the plasma to s.c. ISF glucose gradient or the delay time [7,8]. Taken together, these results imply that s.c. ISF fluid is not derived from tissues that appreciably increase glucose uptake in response to insulin (i.e.…”

“…Clinical concerns regarding this approach include the lag time in equilibration of glucose across the capillary endothelial barrier [2], possible errors in sensor glucose resulting from changes in the plasma to ISF glucose gradient [3], and protracted recovery times following hypoglycaemia [4,5]. Several groups have suggested that s.c. ISF glucose can fall in advance of plasma glucose if the fall in glucose is due to increased glucose uptake in peripheral tissues [6][7][8] or that the response time may be different for falling vs rising glucose signals [9].…”

“…the recovery-depends on the dialysis flow rate, the membrane pore size and the probe dimensions, making data interpretation difficult [6]. An alternative to microdialysis is to use an amperometric glucose sensor and analyse the data using a two-compartment model of plasma and ISF glucose [7,8]. In the model (Fig.…”

Frequency and Temporal Profile of Poststroke Hyperglycemia Using Continuous Glucose Monitoring

“…The CGMS has been shown to accurately track rapid changes over a range of interstitial fluid glucose concentrations with an acceptable time lag (21,22). In outpatients, the CGMS has been documented to be an accurate and reliable tool for assessing glycemic stability (23,24).…”

Acurácia, utilidade e complicações da monitorização subcutânea contínua da glicose (CGMS) em pacientes pediátricos com diabetes tipo 1

“…[20][21][22][23] These data showed that the CGMS is very useful to detect postprandial hyperglycemia. Recent data of 91 DM1 patients estimate that the accuracy of the CGMS sensor is more effective in elevated glucose levels than in hypoglycemic state.…”