Freestyle glucose meter

Male C57BL/6J mice, 8 weeks old (18–22 g of body weight), were purchased from the experimental Animal Center of Beijing University of Medical Science (Beijing, China) and allowed to acclimate for 2 weeks. All mice were housed in the animal facility of the Jilin University Animal Center at 22°C with a 12:12-h light-dark cycle and free access to rodent chow and tap water.
In order to establish type 2 diabetic model, the combined strategy of a HFD (Shanghai SLAC laboratory Animal Co., Ltd., 40% of calories from fat) and STZ (Sigma Chemical, St. Louis, MO) treatment was applied in our study. The mice were fed with HFD for 12 weeks to induce obesity, characterized by abnormal glucose tolerance and insulin resistance. The age-matched nondiabetic mice were fed with a standard diet (SD, Shanghai SLAC laboratory Animal Co., Ltd., 10% of calories from fat). Then, the mice fed with HFD were intraperitoneally given a single injection of STZ at 50 mg/kg body weight. In addition, the mice fed with SD were given an injection of equivalent volume of citrate buffer. Blood glucose level was examined using a FreeStyle glucose meter (Abbott Diabetes Care, Alameda, CA) 3 days after the injection of STZ. Mice were considered diabetic when blood glucose exceeded 12 mmol/L. Next, mice were continued to feed with the corresponding diet for another 4 or 8 weeks.

Mice were food-restricted by receiving about 1.21 g of their corresponding post-weaning diet (LDD or HDD) 2 h before the dark phase, as described above. On the following day, mice were decapitated either in the fasted state (~3 h into the LP), or exactly 4 h after administration of a ¹³C starch bolus (~5 h into the LP). No anaesthesia was used, to prevent effects on glucose levels. Glycaemia was determined in whole blood directly after sacrifice using a Freestyle glucose meter (Abbott Diabetes Care, Hoofddorp, The Netherlands). The liver was excised, weighed, separated into lobes, and snap-frozen in liquid N₂. The luminal content of the small intestine was gently pressed out, weighed, and snap-frozen. Samples were then stored at −80 °C.

Mice were food restricted (1.1 g HFD) for 16 h, starting at ZT = 11. Half of the mice was sacrificed in the post-absorptive state, and the other half was administered the liquid mixed meal with ¹³C glucose by oral gavage and sacrificed after 45 min (postprandial state) by decapitation. Trunk blood was collected in MiniCollect serum tubes (Greiner Bio-One, Alphen aan de Rijn, The Netherlands). Serum was separated by centrifugation at 4 °C for 10 min at 3000 × g, aliquoted, and stored at −80 °C. Glucose was measured in whole blood with a Freestyle glucose meter (Abbott Diabetes Care, Hoofddorp, The Netherlands) directly after sacrifice.