INS and diabetes mellitus: Notably, exendin-4 markedly improved both diastolic function (as indicated by mitral valve E/A, LV isovolumetric relaxation time, and myocardial performance index) and ECM remodelling in STZ mice, whereas insulin-treated animals, which demonstrated similar metabolic benefits (and indeed tended to exhibit lower blood glucose and better pancreatic morphology), displayed equivalent cardiac dysfunction/remodelling to STZ controls, strongly suggesting that exendin-4 exerts direct cardioprotective actions in diabetes.