Abstract Background Transcatheter aortic valve implantation (TAVI) induces reverse cardiac remodelling, an important outcome associated with lower mortality. Diabetes mellitus (DM) is common among TAVI patients and is one of the fastest growing chronic conditions worldwide. Despite its propensity to adversely affect myocardium, the influence of DM on post-TAVI remodelling remains poorly understood. Purpose To characterise the influence of DM on cardiac remodelling following TAVI. Methods Retrospective analysis of 202 patients undergoing TAVI at an Australian tertiary centre. 12-month myocardial remodelling was compared between DM and no DM groups. Results Of 202 patients, median age 82 (IQR: 76, 86) years, 50% female and median STS score 3.5 (2.5, 4.9), 62 (31%) had Type II DM. A robust multivariable analysis (C-Statistic 0.83) revealed DM (adjusted odds ratio [aOR] 2.3, p=0.042) and ≥ mild post-procedural paravalvular regurgitation (aOR 2.5, p=0.027) were independent predictors of poor left-ventricular mass index regression (LVMIr). Among diabetic patients, suboptimal disease control was associated with inferior LVMIr (6% vs -9%, p=0.011), while insulin dependency was not (-3% vs 2%, p=0.489). At 12-months, no differences were found in left-atrial remodelling, left and right-ventricular function, and prosthetic valve performance between DM and no DM groups. Poor LVMIr was associated with lower survival in Kaplan Meier analysis (65% vs 85%, log-rank p=0.049). Conclusion Among patients undergoing TAVI, those with DM demonstrate poorer LVMIr at 12-months. Improved glycaemic control may serve as an important strategy to optimise myocardial remodelling in diabetic patients undergoing TAVI.12-Month LVMI Regression