Skip to main content

Glycemia in blood, brain and subcutaneous tissue measured by a continuous glucose monitoring system


Continuous glucose monitoring system (CGMS) technology provides the opportunity to measure glycemia in different tissues [1]. The aim of our study was to determine the lag-time between blood, brain and adipose tissue during rapid glucose changes.


Fifteen male hereditary hypertriglyceridemic rats underwent the experimental protocol. After intraperitoneal anesthesia, the internal jugular vein and carotid artery were catheterized. A CGMS sensor (Medtronic) was inserted into the brain by micromanipulators and to the abdominal subcutaneous tissue. At the beginning of the experiment (-120 minutes), basal glycemia was measured and calibration of the sensors was started. Thereafter, insulin infusion was started (50 mU/kg/minute) and 20% glucose at a variable rate of infusion. Blood glucose was measured every 5 minutes with manual correction of the glucose infusion rate to maintain the glycemia level of 6 mmol/l. At a time of -10 minutes, the calibration procedure was finished and actual glycemia was recorded to sensors. At a time of 0 minutes, a bolus of glucose 0.5 g/kg was administered; and at a time of 50 minutes, a bolus of insulin 5 IU/kg was administered. Moreover glucose and insulin infusion were stopped at this time. The experiment was finished at time 130 minutes and animals were euthanized.


After an intravenous glucose bolus of 0.5 g/kg, glycemia rose rapidly to 14 mmol/l in 5 minutes. On the contrary, the glucose content in the brain and subcutaneous tissue was increased in a slower manner, with a maximum in about 50 minutes (brain) and 60 minutes (subcutaneous tissue). Intravenous insulin bolus of 5 U/kg was followed by lowering blood glucose concentration to a minimum of 4.5 mmol/l. The brain and subcutaneous tissue glucose content decreased slowly to a minimum of 4.2 mmol/l (brain) and 5.5 mmol/l (subcutaneous tissue). The median glucose lag-time blood versus brain and blood versus subcutaneous tissue was 10 (10; 15) minutes and 15 (15; 25) minutes, respectively (P = 0.01).


Contrary to a previous study, which showed no changes in glucose dynamics after a bolus of glucose between brain, adipose tissue and muscle, our data showed that glucose in the brain follows blood excursions during acute glycemic changes more closely compared with subcutaneous tissue [2].


  1. Penicaud L, et al.: Curr Opin Clin Nutr Metab Care. 2002, 5: 539-543. 10.1097/00075197-200209000-00013

    Article  CAS  PubMed  Google Scholar 

  2. Nielsen JK, et al.: Diabetes. 2005, 54: 1635-1639. 10.2337/diabetes.54.6.1635

    Article  CAS  PubMed  Google Scholar 

Download references

Author information

Authors and Affiliations


Rights and permissions

This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and Permissions

About this article

Cite this article

Zourek, M., Jankovec, Z. & Hykova, P. Glycemia in blood, brain and subcutaneous tissue measured by a continuous glucose monitoring system. Crit Care 15 (Suppl 1), P404 (2011).

Download citation

  • Published:

  • DOI:


  • Subcutaneous Tissue
  • Insulin Infusion
  • Glucose Content
  • Glucose Infusion Rate
  • Continuous Glucose Monitoring System