NPPA and type 1 diabetes mellitus: We established HFpEF hearts in STZ-induced T1DM rats exhibiting significant physical (lower BW and higher BG), biochemical (increased TG and NEFA and reduced insulin) and physiological (reduced EDV, stroke volume, stroke work, end systolic elastance and cardiac output) changes, as well as cardiac fibrosis, conversion of α-MHC and β-MHC, and increased ANF mRNA levels.