AIM: To investigate the association between sleep quality outcomes and measures of cardiac autonomic function and to assess the predictive ability of sleep quality outcomes for cardiac autonomic neuropathy (CAN) in type 2 diabetes mellitus (T2DM). METHODS: Fifty patients with T2DM (age, 51.3+/-7.01years; glycemic control, 8.4+/-1.65%) completed the study. Patients were diagnosed for CAN using the standard clinical autonomic test battery and were also assessed for heart rate variability (HRV) under resting conditions. Sleep quality was examined using the Pittsburg Sleep Quality Index (PSQI). RESULTS: Sleep duration, sleep onset latency, sleep efficiency, daytime dysfunction and global PSQI score showed significant correlations with measures of cardiac autonomic control (p<0.05). At an optimal cut-off of</=5.83h (area under the curve: 0.76, p=0.0003; sensitivity: 50%; specificity: 94.4%), sleep duration predicted occurrence of CAN (odds ratio, confidence interval: 0.18, 0.04-0.70; p=0.01) in T2DM after adjusting for various clinical confounders. CONCLUSION: Findings of the present study suggest that subjective sleep outcomes such as sleep duration, sleep onset latency, sleep efficiency, daytime dysfunction and overall sleep quality are associated with the indices of cardiac autonomic function in T2DM. Moreover, short sleep duration may be considered a predictor in the occurrence of CAN in these patients. Considering the role of sleep in the pathophysiology of CAN, sleep should be routinely examined in patients with T2DM and appropriate therapeutic interventions should be implemented particularly in case of reduced sleep duration.