Objective:To observe the relationship between the different stages of type 2 diabetes mellitus(T2DM)and the intestinal flora and verify its underlying mechanism.Methods:T2DM rats were generated by high-fat diet(HFD)combined with intraperitoneal streptozo-tocin(STZ)injection.The rats were divided into four groups:the control group(fed with normal feed for 1 month),the HFD group(fed with HFD for 1 month),the T2DM group(HFD combined with STZ and blood glucose＞11.1 mM),and the unformed T2DM model(Un-mod)group(HFD combined with STZ and blood glucose＜11.1 mM).Feces were collected,and bacterial communities in the fecal samples were analyzed by 16S rRNA gene sequencing.The content of short-chain fatty acids(SCFAs)in feces was measured by gas chromatography.Western blot and quantitative real-time polymerase chain reaction were used to detect the expression of G protein-coupled receptor 41(GPR41)and GPR43.Results:At different stages of T2DM,the intestinal flora and SCFAs content of rats were significantly decreased(all P＜.05).Our results indicated that g_Prevotella had a significant negative correlation,and g_Ruminococcus_torques_group and g_lachnoclastic had a significant positive correlation with blood glucose.The content of SCFAs,in particular acetate and butyrate,in rat feces of different stages of T2DM were significantly reduced,as well as GPR41 and GPR43 expression.The results in the Un-mod group were similar to the T2DM group,and the expression of GPR41 and GPR43 proteins were significantly higher than those in the T2DM group(both P＜.001).Conclusion:The intestinal flora-SCFAs-GPR41/GPR43 network may be important in the development of T2DM.Decreasing blood glucose levels by regulating the intestinal flora may become a new therapeutic strategy for T2DM,which has very important clinical and social values.