Mice and type 2 diabetes mellitus (T2DM) establishment

The animal experiments were complied with the ARRIVE (Animal Research: Reporting of In Vivo Experiments) guidelines and approved by the Ethics Committee of the College of Stomatology, Chongqing Medical University. 6-week-old male C57BL/6 mice were purchased from the SJA laboratory animal CO. LTD (Hunan, China) and were housed in a specific pathogen-free condition: room temperature 22 ± 2 °C, 12 h light/dark cycle and water ad libitum. 36 mice were randomly divided into two groups (n = 18/group) and fed with standard diet or high fat/high glucose diet (HFHG, D12492, Research Diets, NJ, USA) respectively. After 8 weeks, HFHG-fed mice weighed up to 30–35 g and were intraperitoneally injected with streptozotocin (STZ, 35 mg/kg, Sigma-Aldrich, MO, USA) for 3 consecutive days, while mice on the standard diet were given citrate buffer. 7 days after the last injection and then once a week after that, blood glucose levels were measured. T2DM was diagnosed in mice with fasting blood glucose levels higher than 16.7 mM and clinical symptoms (increased food and water consumption, increased urine output and weight loss).