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Insulin tolerance tests are a standard and common method for evaluating the insulin sensitivity of an animal. In this assay, animals are fasted to normalize blood glucose and then challenged by an intraperitoneal injection of insulin. As glucose is transported into tissues and glucose production is suppressed, glucose levels drop. A more insulin-sensitive animal will have a larger decrease in blood glucose. This has advantages over a glucose tolerance test which measures both insulin sensitivity and insulin responsiveness. ==SOP==*[[Safety and Animal Training]]*[[SOP - Needle Capping]] ==Materials (Bring Downstairsto Room)==
*Glucometer - AccuChek Advantage
*Glucose Test Strips - AccuChek Comfort Curve or equivalent
*Scale
*Beaker for weighing mice
*echoMRI if the mice differ in body fat levels (see [[#Taking_into_Account_Differences_in _Fat_Mass]]below)
*Syringes
*0.1 U/mL humulin in PBS (make as 10uL of 100 U/mL in 10 mL, sterile filtered). This will correspond to 1 U/kg injections. If you are using a higher or lower dose of insulin, add more or less to the 10 mL of PBS, so that injections are 10 uL/g of mass.
===Taking into Account Differences in Fat Mass===
Since most glucose is taken up into non-fat tissues, it can be confounding if you dose based on total body weight, and the two groups differ greatly with respect to the amount of fat mass. A fat mouse and a lean mouse are likely to have very similar fat-free masses, and by giving more insulin to the fatter animal (because body weight is higher) you might make the fatter mouse seem more insulin sensitive, but really its just responding to a larger amount of insulin. In these cases the preferred practice is to '''measure fat free mass by echoMRI''', and then dose animals at approximately 1 U/kg of lean mass for a lean animal or 2.5 U/kg of lean mass for an obese animal.
[[Category:Animal Work]]
[[Category:Mouse Work]]
[[Category: Glucose]]