Background and objective: Currently, there are few studies on the application of positron emission tomography-computed tomography (PET/CT) in patients with diabetes mellitus (DM) complicated with cerebral hemorrhage (CH), and its accuracy in the evaluation of this disease remains to be determined. Accordingly, by analyzing the application value of PET/CT in hemorrhagic lesions and glucose metabolism (CMRglc) of diabetic patients complicated with CH, this study lays a foundation for PET/CT employment on the disease and provides reliable reference and guidance for future clinical diagnosis and treatment of this patient population. Methods: Sixty-nine diabetic patients complicated with CH (research group, RG) and 58 patients with simple DM (control group, CG) treated in our hospital between March 2019 and January 2021 were selected as the research participants. All the enrolled subjects underwent F-18-FDG PET/CT examination. The differences in standard uptake values (SUVs) and CMRglc in the brain regions of interest (frontal lobe, FL; parietal lobe, PL; temporal lobe, TL; occipital lobe, OL; thalamus; basal ganglia, BG; cerebellum, CB, and; brainstem, BS) were evaluated. In RG, the alterations of hemorrhagic lesions before and after treatment and their relationship with the Intracerebral Hemorrhage (ICH) Score were analyzed. Results: RG presented lower SUVs of FL, PL, TL, OL, thalamus, BG and CB in the left and right hemispheres while higher CMRglc level than CG (P<0.05). In RG, the pixel brightness of the bleeding site and the ischemic area around the hemorrhagic lesion increased significantly after treatment (P<0.05). Pearson correlation coefficient analysis identified an inverse association between the pixel brightness of the bleeding site and the ICH score in RG before and after treatment (P<0.05). Conclusions: F-18-FDG PET/CT has an excellent evaluation effect on CMRglc and hemorrhagic lesions in brain tissue of diabetic patients complicated with CH. It can assist clinical practice to further understand the development and changes of patients' illness in the future, and provide protection for patients' life and health.