Type 2 diabetes and Parkinson’s both affect aging populations and share several biological similarities, including toxic protein accumulation, lysosomal and mitochondrial dysfunction, and chronic systemic inflammation.
Many studies have examined a possible relationship between the two diseases, but the studies have often come to conflicting conclusions.
Researchers at Queen Mary University of London sought to reconcile these conflicts through a comprehensive review of all available studies on the subject.
Out of 33,408 articles, the researchers selected 28 that were either observational studies specifically examining the possible effects of type 2 diabetes on Parkinson’s disease or studies analyzing how diabetes in general might affect the progression of Parkinson’s disease.
From nine studies that specifically focused on type 2 diabetes, the researchers calculated that people with type 2 diabetes were 1.21 times more likely to develop Parkinson’s disease.
Inclusion of studies that included diabetes in the analysis yielded an “all-zero effect,” suggesting that only type 2 diabetes increases the risk of Parkinson’s.
In both cases, the researchers saw no influence of age or gender.
The analysis also found an association between type 2 diabetes and faster progression of both motor symptoms and cognitive decline in Parkinson’s disease.
To get some insight into whether the relationships the team discovered were truly causal or just random, they applied a technique called Mendelian randomization to a separate analysis. Mendelian randomization relates well-understood genetic variations to observable outcomes such as disorders.
This analysis supported the association between type 2 diabetes (T2D) and faster progression of motor symptoms in Parkinson’s, but found “no convincing evidence” to support the possible association with cognitive decline.
“This study summarizes the results of many other studies to provide compelling evidence that type 2 diabetes is likely to affect not only Parkinson’s risk but also the progression of Parkinson’s disease,” said Alastair Noyce, PhD, the lead author of the study, in a press release.
“There are many treatment strategies for type 2 diabetes, including prevention strategies, which can be redefined for the treatment of Parkinson’s,” he added.
Although this study did not examine the potential effects of diabetes drugs, previous studies have found evidence that antidiabetic drugs lower the risk and severity of Parkinson’s disease.
“Treating T2D can slow the progression of T2D [Parkinson’s]”The researchers concluded.” Hence, careful screening for T2D and early treatment for T2D in patients with [Parkinson’s] can be advisable. “
Forest Ray received his PhD in systems biology from Columbia University, where he developed tools to match drug side effects to other diseases. Since then he has worked as a journalist and science journalist, dealing with topics ranging from rare diseases to the interface between environmental science and social justice. He currently lives in Long Beach, California.
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Ana received her PhD in Immunology from the University of Lisbon and worked as a postdoctoral fellow at the Instituto de Medicina Molecular (iMM) in Lisbon, Portugal. She holds a BSc in Genetics from the University of Newcastle and a Masters in Biomolecular Archeology from the University of Manchester, England. After leaving the lab to pursue a career in science communication, she was director of science communication at iMM.