OBJECTIVE—To investigate the effects of fenofibrate and coenzyme Q10 (CoQ) on diastolic function, ambulatory blood pressure (ABP), and heart rate (HR) in type 2 diabetic subjects with left ventricular diastolic dysfunction (LVDD).RESEARCH DESIGN AND METHODS—We randomized, double-blind, 74 subjects to fenofibrate 160 mg daily, CoQ 200 mg daily, fenofibrate 160 mg plus CoQ 200 mg daily, or matching placebo for 6 months. Echocardiography (including tissue Doppler imaging) and 24-h ABP and HR monitoring were performed pre- and postintervention.RESULTS—Neither fenofibrate nor CoQ, alone or in combination, altered early diastolic mitral annular myocardial relaxation velocity (E′), early-to-late mitral inflow velocity ratio (E/A), deceleration time, isovolumic relaxation time, or the ratio of early mitral flow velocity to early diastolic mitral annular myocardial relaxation velocity (E/E′) compared with placebo (P > 0.05). Fenofibrate and CoQ interactively (P = 0.001) lowered 24-h systolic blood pressure (−3.4 ± 0.09 mmHg, P = 0.010), with a prominent nocturnal effect (−5.7 ± 1.5 mmHg, P = 0.006). Fenofibrate (−1.3 ± 0.5 mmHg, P = 0.013) and CoQ (−2.2 ± 0.5 mmHg, P <0.001) independently lowered 24-h diastolic blood pressure. Fenofibrate reduced 24-h HR (−3.3 ± 0.5 beats/min, P <0.001), but CoQ had no effect on HR.CONCLUSIONS—In type 2 diabetic subjects with LVDD, neither fenofibrate nor CoQ, alone or in combination, improved diastolic function significantly. However, fenofibrate and CoQ independently and interactively lowered 24-h blood pressure, and fenofibrate alone reduced 24-h HR.