Glucose Metabolism

Glucose metabolism in mice can be assessed using a panel of standalone in vivo tests or coupled with metabolic cage or environmental housing experiments. Assessing glucose and insulin levels in the blood in response to a variety of stimuli enables a broader metabolic characterization of your mouse.

Fasting Glucose and Insulin

Determining fed and fasting blood glucose and insulin levels is a useful strategy to screen for potential disturbances in glucose metabolism in your model [2]. Glucose is measured using a handheld blood glucose meter and insulin is assessed in plasma via ELISA.

Glucose Tolerance Test

The glucose tolerance test (GTT) assesses the disposal of a glucose bolus following administration either via intraperitoneal injection (IP-GTT) or oral gavage (O-GTT) in conscious mice [1,2,4]. Note that only the O-GTT assesses the incretin effect [3]. The results of the test determine the glucose tolerance, which depend on both insulin secretion and insulin action. Important considerations include glucose dose and fasting duration.

Insulin Tolerance Test

The insulin tolerance test (ITT) assesses the decrease in blood glucose following an insulin bolus administered via intraperitoneal injection (IP-ITT) in conscious mice [2,4]. The results of the test determine the insulin sensitivity. Important considerations include insulin dose and fasting duration.

Pyruvate Tolerance Test

The pyruvate tolerance test (PTT) assesses the appearance of glucose following a pyruvate bolus administered either via intraperitoneal injection (IP-PTT) or oral gavage (O-PTT) in conscious mice. The results of the test estimate hepatic gluconeogenesis.

Glucose Stimulated Insulin Secretion

Glucose Stimulated Insulin Secretion (GSIS) assesses the appearance of insulin following either intravenous, intraperitoneal or oral glucose bolus administration. The results of the test determine insulin secretion, which can aid in interpretation of the GTT. Important considerations include glucose dose, fasting duration and route of administration. This can be done in combination with GTTs.

References:

1. Andrikopoulos et al., Evaluating the glucose tolerance test in mice. Am J Physiol Endocrinol Metab 295: E1323–E1332 (2008)
2. Ayala et al., Standard operating procedures for describing and performing metabolic tests of glucose homeostasis in mice. Disease Models & Mechanisms 3, 000-000 (2010)
3. Kazafeos K, Incretin effect: GLP-1, GIP, DPP4. Diabetes Res Clin Pract. 93(1):S32-6 (2011)
4. McGuinness et al., NIH experiment in centralized mouse phenotyping: the Vanderbilt experience and recommendations for evaluating glucose homeostasis in the mouse. Am J Physiol Endocrinol Metab 297: E849 –E855 (2009)