Glucose Tolerance Test in Diabetic Mice

Homozygous db/db mice for spontaneous mutation (Lepr^db) and heterozygous mice for control were fasted for 4 h, and then baseline glucose concentrations were assessed using an Accu-Chek Compact Plus glucometer (Roche Diagnostics, Indianapolis, IN) from tail blood. Mice were then injected (intraperitoneally, i.p) with 1 mg/g glucose. Blood glucose was determined at 15, 30, 60, 120, and 240 min following i.p. injection of glucose. Total serum fasting glucose from tail blood were also detected with a CardioChek PA system (PTS Diagnostics, Indianapolis, IN) under the manufacturer’s instructions. Detailed methodology was described as the previous protocol with a minor modification (Chen et al., 2015 (link); Zhang et al., 2017 (link)). Insulin level in serum was determined using a standard curve obtained from the standards provided by the kit. Serum insulin was assessed using a Triglyceride Colorimetric Assay Kit from Cayman Chemical (Ann Arbor, MI) according to the manufacturer’s instructions (Zhang et al., 2017 (link)).