Fig. 1

Experimental design. After 3 days of acclimatization, rats were randomly divided into five groups: control group (CON), model group (MOD), positive control group (MET), water extraction group of PPM (low high dose groups) (PPM-L) and water extraction group of PPM (high dose groups) (PPM-H). Except for the CON group, all rats received a high-fat diet for 12 consecutive weeks. Rats were fasted for 2 h each day prior to administration of therapeutic agents. In the CON and MOD groups, rats were gavaged with normal saline, whereas in the MET group, rats were gavaged with 90 mg·kg^− 1 Metformin hydrochloride, in the PPM-L group, rats were gavaged with 0.405 g·kg^− 1 PPM, and in the PPM-H group, rats were gavaged with1.62 g·kg^− 1 PPM