A large assortment of comorbid diseases is associated with PD. Emerging evidence shows that chronic diseases such as diabetes, depression, anemia, and cancer may be associated with the pathogenesis and progression of PD. Studies have identified comorbid conditions such as bone fractures, cancer, dementia, diabetes, and stroke in PD patients. Recent research indicates that certain comorbidities may enhance the risk of PD and precede the manifestation of motor symptoms. Furthermore, medications for treating diabetes and cancer have prompted neuroprotective effects in PD models. Yet, the mechanisms underlying the cooccurrence of these diseases remain unclear.