Abstract:[Objective] To investigate the relationship between bone mineral density and cognitive impairment in type II diabetes melli-tus. [Methods] From July 2020 to September 2021, 45 patients with type II diabetes mellitus (T2DM) were enrolled in this study. Blood glu-cose, glycated hemoglobin A1c (HbA1c), serum osteocalcin (OC) and bone mineral density (BMD) were detected, while the Montreal Cogni-tive Assessment (MoCA) was used to evaluate the cognitive level of the patients. [Results] According to the results of BMD, 16 cases were os-teoporosis, 17 cases were bone mass reduction, and 12 cases were normal bone mass. The incidence of cognitive impairment was 15/16(93.8%) in the osteoporosis group, whereas 13/17 (76.5%) in the bone mass reduction group, and 3/12 (25.0%) in the normal bone massgroup. The patients were divided into two groups according to whether they had cognitive impairment. There were no significant differencesin age, gender composition, weight, height, BMI, HbA1c and years of education between the two groups (P<0.05), the cognitive impairmentgroup had significantly lower MoCA score, OC and BMD than the normal cognition group (P<0.05). [Conclusion] The incidence of cogni-tive impairment is significantly increased with the decrease of BMD in T2DM.