GPBAR1 and diabetes mellitus: To explore the role of the DCA receptor TGR5 in DbCM, cardiac-specific TGR5-knockout (αMHC-Gpbar1fl/fl; TGR5ΔCM) mice (Supplementary Fig. 1a,b) were used in a diabetes model induced by HFD/STZ, representing late-stage type 2 diabetes.