Objective To analyze the relationship between type 2 diabetes mellitus (T2DM) and cognitive disorder in middle-aged and elderly patients with Parkinson’s disease (PD), and to identify risk factors for cognitive disorder in PD patients. Methods The clinical data of patients aged ≥50 years and hospitalized for PD in Xijing Hospital of Air Force Medical University from Jan. 2010 to Dec. 2021 were collected, including demographic characteristics, general clinical features, laboratory indicators, etc. The cognitive status was evaluated by mini-mental state examination (MMSE). A total of 281 PD patients were assigned to T2DM group or non-T2DM group, and MMSE original score, standardized score, and cognitive status were compared between the 2 groups. The 281 patients were reassigned to normal cognition group or abnormal cognition group, then multivariate logistic regression was used to analyze the risk factors of cognitive disorder in middle-aged and elderly patients with PD. Results The MMSE original score and standardized score in the T2DM group were significantly lower than those in the non-T2DM group (23[18, 25] vs 24[21, 27], P＝0.011; －1[－3, 2] vs 1[－1, 3], P＝0.004), and the detection rate of cognitive disorder was significantly higher than that of the non-T2DM group (53.57%[45/84] vs 33.50%[66/197], P＝0.002). Multivariate logistic regression analysis showed that T2DM (odds ratio[OR]＝2.452, 95% confidence interval[95%CI]1.397-4.306, P＝0.002), place of residence (OR＝2.208, 95%CI 1.261-3.868, P＝0.006), and age (OR＝1.054, 95%CI 1.006-1.104, P＝0.028) were risk factors for cognitive disorder in middle-aged and elderly patients with PD, while serum uric acid (OR＝0.274, 95%CI 0.098-0.768, P＝0.014) was protective factor for cognitive disorder in middle-aged and elderly patients with PD. Conclusion T2DM, rural area, advanced age, and hypouricemia are independent risk factors for cognitive disorder in middle-aged and elderly patients with PD. For middle-aged and elderly PD patients with T2DM, screening for cognitive disorder should be strengthened for early prevention and intervention.