KLK (kallikrein-related peptidase) 8 deficiency attenuates diabetic cardiac diastolic dysfunction. Both wild-type (KLK8+/+) and KLK8-deficient (KLK8-/-) mice were injected with STZ to construct diabetic mice. Cardiac diastolic function was assessed by using echocardiographic analysis at 16 weeks after STZ injection. A, Representative pulse doppler images of echocardiographic analysis. B-D, KLK8 deficiency partially rescued the reduced E/A ratio (B), and reduced E-wave deceleration time (C) and IVRT (D) in STZ-induced diabetic mice. E/A, ratio of E wave to A wave amplitude; Deceleration Time, E-wave deceleration time; IVRT, isovolumic relaxation time. Data are expressed as means ± SEM (n = 7). *p < 0.05, **p < 0.01, ****p < 0.0001.