Animals

Male homozygous leptin receptor-deficient T2DM (Lepr db/Lepr db, db/db) mice and their littermate m/m (m/m) mice were purchased from GemPharmatech Co., Ltd. (Nanjing, China). C57BL/6J-Khk^emlcyagen (Khk knockout, Khk KO) mice were generated by the CRISPR/Cas9 method (Cyagen Biosciences (Suzhou) Inc., Jiangsu, China). All of the mice were housed in a pathogen-free, temperature-controlled environment with a temperature of 22 ± 2 °C, relative humidity of 60 ± 70%, and a light/dark cycle of 12/12 h and fed ad libitum in a standard laboratory. All animals were allowed to acclimate in the animal facility for at least one week prior to being handled. The body weight and water intake of the mice were monitored every 2 days. All selected mice were randomly divided into specified groups. All animal studies (including the mouse euthanasia procedure) were approved by the Animal Care Institution of Xi’an Jiaotong University and conducted according to the ARRIVE guidelines (NO. 2019-060).