Abstract
Glucose tolerance test is a standard procedure that addresses how quickly exogenous glucose can be cleared from blood. Specifically, uptake of glucose from the blood by cells is regulated by insulin. Impairment of glucose tolerance (i.e, longer time to clear given amount of glucose) indicates problems with maintenance of glucose homeostasis (insulin resistance, carbohydrate metabolism, diabetes, etc). According to the WHO, in a standard oral glucose tolerance test (OGTT), glucose level should be below 7.8 mmol/L (140 mg/dl) at 2 h. Levels between this and 11.1 mmol/L (200 mg/dl) indicate “impaired glucose tolerance”, and any level above 11.1 mmol/L (200 mg/dl) confirms a diagnosis of diabetes.
Materials and Reagents
Equipment
Procedure
Note: All the following experimental procedures that involve animals (rodents) should receive approval from IACUC or equivalent committee. Humane treatment of animals should be practiced all the time. In the Cavener lab, we used glucose tolerance test extensively in the characterization of mice lacking Pek/Perk, encoding an eIF2alpha kinase that is crucial to translational control and ER homeostasis (Zhang et al., 2002).
Representative data
Figure 1. This figure is adapted from the original (Zhang et al., 2002). Fasted B6 mice were injected at time zero with glucose, and blood glucose levels were monitored and normalized to the value of time zero. Each data point represents the average of three to five individual mice. The baseline value of blood glucose is typically ~100 mg/dl. Representative data are shown here.
Notes
Please note that mice of different genders, ages, and inbred backgrounds can show different responses to glucose. Certain strain-specific phenotype data can be found at http://phenome.jax.org/db/q?rtn=meas/methodologies.
Recipes
Acknowledgments
This protocol was adapted from work performed by Dr. Maureen Gannon at the Vanderbilt University Medical Center. PZ was supported by a research assistantship in the Cavener lab at the Pennsylvania State University.
References
If you have any questions/comments about this protocol, you are highly recommended to post here. We will invite the authors of this protocol as well as some of its users to address your questions/comments. To make it easier for them to help you, you are encouraged to post your data including images for the troubleshooting.
Hi Sudheer,We have never measured GLP-1 for our mice in these tests. Here is some reference that could be interesting to you: http://www.pnas.org/content/97/12/6874.long It seemed that this group measured GLP-1 at an early time point (15min after the administration of glucose).Best,Peichuan
Thank you somuch Peichuan...
Hello, sorry that I couldn't find the raw data as I did this work a long time ago. I contacted a former colleague and haven't got any reply yet. I checked both my own paper and another reference http://ajpendo.physiology.org/content/295/6/E1323.full Andrikopoulos et al, Am J Physiol Endocrinol Metab (2008). I could tell from my paper that the levels should be about 320mg/dL (15min) and 350mg/dL (45min). Estimated serum glucose levels from the other paper: ~320mg/dL (15min), 300mg/dL (30min), 220mg/dL (60min), 120mg/dL (120min). Hope that these data points would serve well as references for your own work.Best luck,P
Hello,We used both B6 black mice as well as littermates (sibling) of the PERK knockout mice as the controls. The fasting plasma glucose level was around 100 mg/dL (~5.5 mmol) or maybe even lower. I recall that the technician moved the mice into a FRESH cage with water just before he left (around 6PM), and then we perform the test next morning or around noon (~16 to 18 hours).The PERK knockout mice had mixed genetic background of B6 and 129. Please be aware that the fasting levels might be different for mice from different backgrouns --- refer to http://ajpendo.physiology.org/content/295/6/E1323.full Andrikopoulos et al, Am J Physiol Endocrinol Metab, 2008.Please feel free to ask us questionsThanks,Peichuan