A, Treprostinil (300 ng/kg/min, osmotic minipumps), alone or in combination with metformin (300 mg/kg, drinking water), was given 7 weeks after a single injection of SU5416 (100 mg/kg) to obese ZSF1 rats. Body weights (B), HbA1c levels (C), glucose tolerant abilities (D), right ventricular systolic pressures (RVSP, E) and the ratio of early diastolic mitral annular velocity to mitral peak velocity of late filling (E/A, F) were measured. The ratio of pulmonary artery acceleration time to ejection time (PAAT/ET, G) and tricuspid annular plane systolic excursion (TAPSE, H) were measured. Data are mean ± SEM; n = 4–13 rats/group; *P < 0.05, **P < 0.01 and ****P < 0.0001 vs. Ln-Su; #P < 0.05, ##P < 0.01, ###P < 0.001 and ####P < 0.0001 vs. Ob-Su; &&&&P < 0.0001 vs. Ob-Su+Tre; $P < 0.05 and $ $P < 0.01 vs. Ob-Su+Met.