Objective The supine-to-standing transcranial Doppler（TCD） technique is suitable for evaluating cardiovascular autonomic dysfunction， and this study aims to assess its performance in predicting adverse outcomes in diabetic patients with or without orthostatic hypotension （OH）. Methods The patients with type 2 diabetes mellitus who were admitted to Department of Endocrinology and Department of Neurology in The Second Affiliated Hospital of Hainan Medical University from August 2020 to May 2023 were enrolled as subjects. Basic clinical data were collected， and supine-to-standing TCD was performed to monitor and record the changes in blood pressure， heart rate， and cerebral hemodynamics in both supine and standing positions. The patients were followed for 2-4 years to record medication， orthostatic intolerance score， and adverse events. The two-independent-samples t test was used for comparison of normally distributed continuous variables between groups， and the Mann-Whitney U test was used for comparison of non-normally distributed continuous variables between groups； the chi-square test was used for comparison of categorical variables between groups. The binary logistic regression analysis was used to investigate the association between the results of supine-to-standing TCD and adverse outcomes. Results A total of 118 patients （96 male patients and 22 female patients） were enrolled， among whom there were 28 patients with OH （23.7%） and 90 patients without OH（76.3%）. During follow-up， 19 patients （16.1%） experienced adverse outcomes （including syncope， falls， and death）.TCD showed that impaired “W” wave recovery in cerebral blood flow in the standing position was an independent risk factor for adverse outcomes in diabetic patients （OR=3.536， 95% CI 1.136-11.006， P=0.029）. Conclusion Vascular reflex failure and paradoxical cerebral vasoconstriction may be the mechanisms for impaired cerebral blood flow recovery in the standing position. TCD testing has an important role in detecting cerebrovascular abnormalities and cerebral hemodynamic changes， especially in diabetic patients with OH， and it has good performance in predicting adverse outcomes.