Left ventricular torsion is increased and cardiac energetics are reduced in uncomplicated type 1 diabetes mellitus (T1DM). Our aim was to determine the relationships of these abnormalities to cardiovascular autonomic neuropathy (CAN) in subjects with T1DM. A cross-sectional study was conducted in 20 subjects with T1DM free of known coronary heart disease attending an outpatient clinic. Cardiovascular autonomic neuropathy was assessed using heart rate variability studies and the continuous wavelet transform method. Left ventricular function was determined by speckle tracking echocardiography. Magnetic resonance spectroscopy and stress magnetic resonance imaging were used to measure cardiac energetics and myocardial perfusion reserve index, respectively. Twenty subjects (age, 35 ± 8 years; diabetes duration, 16 ± 9 years; hemoglobin A(1c), 8.0% ± 1.1%) were recruited. Forty percent of the subjects exhibited definite or borderline CAN. Log peak radial strain was significantly increased in subjects with CAN compared with those without (1.56 ± 0.06 vs 1.43 ± 0.14, respectively; P = .011). Data were adjusted for log duration of diabetes, and log left ventricular torsion correlated (r = 0.593, P = .01) with log low-frequency to high-frequency ratio during the Valsalva maneuver. Log isovolumic relaxation time correlated significantly with log Valsalva ratio and log proportion of differences in consecutive RR intervals of normal beats greater than 50 milliseconds during deep breathing. However, CAN did not correlate with cardiac energetics or myocardial perfusion reserve index. Spectral analysis of low-frequency to high-frequency ratio power during the Valsalva maneuver is associated with altered left ventricular torsion in subjects with T1DM. Parasympathetic dysfunction is closely associated with diastolic deficits. Cardiovascular autonomic neuropathy is not however the principal cause of impaired cardiac energetics. The role of CAN in the development of cardiomyopathy warrants further evaluation.