Asked for her perspective, Stella Papa, MD, of Emory University School of Medicine in Atlanta, who was not involved in the study, told MedPage Today, “A relationship between Parkinson’s disease and type 2 diabetes has been suspected for a long time, but in spite of a number of supporting studies, we have been lacking clear, confirmatory data.”
Oxidative stress, insulin resistance, inflammation, and abnormal protein accumulation are pathogenic mechanisms the two diseases share, she noted.
“In particular, there is a growing interest around the idea that the misfolded amyloid polypeptide in the pancreatic beta islet, which can form fibrils and propagate in diabetes mellitus, could interact in a cross-seeding fashion with alpha-synuclein aggregation leading to neurodegeneration of PD. In other words, a common prion-like basis underlying both type 2 diabetes and PD may synergize to increase the risk for their association.”
There were several study limitations, Warner and colleagues noted: They were unable to adjust for medications and smoking in the analysis, and determined diabetes cases based on the first recorded hospital diagnosis, not the first point of onset. And because this was a hospital-based study, patients diagnosed with diabetes may have had a more severe form of the disease than patients diagnosed in a clinic.