Objective:To analyze the relationship between T2DM complicated with hypertension and cognitive decline in middle-aged and elderly individuals, as well as the associated influencing factors. Methods:Middle-aged and elderly subjects who were treated at Sir Run Run Hospital Affiliated to Nanjing Medical University from September 2020 to September 2022 were enrolled and divided into four groups:patients with type 2 diabetes mellitus complicated with hypertension (T2DMH group),patients with type 2 diabetes mellitus alone (T2DM group),patients with hypertension alone (HBP group),and healthy controls (HC group).Clinical data were collected from four groups of patients. Cognitive and functional indicators were assessed using the MoCA, AVLT, TMT and DST.Cognitive function was compared among the four groups, and the associated influencing factors were analyzed by multiple regression analysis. Results:A total of 369 patients were enrolled in this study. These patients were assigned to four groups: the T2DMH group (n=105), T2DM group (n=106), HBP group (n=89), and HC group (n=69). No statistically significant differences were observed in age and years of education among the four groups (P>0.05), indicating good comparability. The islet function of the T2DMH group was significantly poorer than that of the HBP and HC groups, with no notable difference compared with the T2DM group (P>0.05). In terms of cognitive functions, the T2DMH group had worse performance in memory cognitive dimensions than the T2DM and HBP groups, and all indicators of cognitive domains in this group were significantly lower than those in the HC group (all P<0.05). Cognitive function was significantly correlated with years of education, histories of T2DM and hypertension, islet function and other indicators (P<0.05). Multiple linear regression analysis showed that years of education was a protective factor for cognitive function, while histories of diabetes and hypertension were risk factors. Additionally, drinking history and some renal function indicators were associated with cognitive function to varying degrees (all P<0.05). Conclusion:Patients with T2DM complicated with hypertension present more severe metabolic disorders, organ damage and impaired islet function. Their cognitive function decreases significantly in multiple dimensions, and the degree of decline is more serious than that in patients with type 2 diabetes mellitus or hypertension alone.History of diabetes and hypertension are core risk factors for cognitive decline in middle-aged and elderly individuals. Increasing years of education, moderate alcohol consumption, and protecting renal and islet function may exert positive effects on preventing and delaying cognitive decline.