Patients with PD had a lower proportion of current smokers and were less likely to drink alcohol or perform regular physical activity (PA); had lower mean body mass index (BMI), total cholesterol, and hemoglobin (Hb) levels; and had a higher prevalence (P < 0.05) of diabetes mellitus, cerebrovascular disease, dementia, irritable bowel syndrome, and constipation and lower prevalence (P > 0.05) of chronic pulmonary disease and metastatic solid tumors than those without PD. Here, GSTM1 is linked to diabetes mellitus.