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Diabetes Not a Risk Factor for Parkinson's Disease

Although the likelihood of having diabetes diagnosed is increased around the time Parkinson's disease is identified, diabetes does not appear to increase the risk of Parkinson's disease, according to findings published in Diabetes Care.

Some studies have found a positive association between diabetes and Parkinson's disease, Dr. Jane A. Driver of Harvard Medical School, Boston, and colleagues point out. It has been suggested that diabetes might promote Parkinson's disease through various pathways, including suppressing neurotransmitter levels, inflammation, oxidative stress, and cerebrovascular disease.

To investigate further, the researchers examined data from the Physicians' Health Study involving 21,841 U.S. male physicians, who were followed for an average of 23.1 years.

The team reports that 423 subjects had the adult-onset type 2 diabetes at the beginning of the study and 1987 men reported developing diabetes during the study. A total of 556 participants reported having Parkinson's disease during follow-up. The average age at diagnosis was 73.1 years.

Compared with non-diabetic men, those with diabetes had a 34-percent increased risk of Parkinson's disease. Excluding subjects who developed vascular disease did not alter this association.

"The highest Parkinson's disease risk was seen in individuals with short-duration, older-onset diabetes without complications," Driver's team reports.

The difference in diabetes incidence between Parkinson's disease patients and matched control subjects was greatest during the year Parkinson's disease was diagnosed and a few years before.

The findings "do not suggest that diabetes is a preceding risk factor for Parkinson's disease," the researchers conclude.

The clustering of diabetes diagnoses around the time of Parkinson's disease identification could be a result of increased medical surveillance, a common underlying biological mechanism, or possibly some influence of Parkinson's disease on diabetes risk


PDF Interprets: Having Diabetes Does Not Increase Risk for Parkinson’s

A study published in Diabetes Care analyzed health data from nearly 22,000 men to determine whether having diabetes increases a person’s risk of developing Parkinson’s.  Lead researcher, Jane A. Driver, M.D., M.P.H., of Harvard Medical School, performed this study with funding from PDF’s 2007-2008 Career Development and Fellowships Program. 

Some earlier studies – but not all – had suggested an association between diabetes and PD.  In this study, Dr. Driver and her colleagues attempted to settle the question by looking at data collected for the Physicians’ Health Study, which included 21,841 male physicians in the United States.  The men were ages 40 to 84 at the beginning of the study in 1982, and researchers followed their health status for an average of 23 years. 

At the study’s start, 423 participants reported having diabetes.  During follow-up, an additional 1,987 developed diabetes and 556 were diagnosed with Parkinson’s. 

The researchers concluded that diabetes is not a risk factor for PD even though they found that men diagnosed with type 2 diabetes were more likely to develop Parkinson’s.  Links between the two diseases are complex.  For example, it could be that people with Parkinson’s are diagnosed with diabetes more frequently because they are visiting their doctors more often. Also, the researchers expected that if diabetes were a cause of PD, men with the most severe diabetes over longer periods of time would be most likely to develop PD.  Instead, the opposite held true: it was men who were recently diagnosed with diabetes, and did not have complications from diabetes, who were at higher risk for PD.  The researchers also suggest that PD could influence diabetes risk, or that an as-yet unknown biological mechanism underlies both diseases.

Overall, this study demonstrates that diabetes is not a risk factor for Parkinson’s disease (PD).


Please note that this study was funded by PDF.  Jane A. Driver was awarded a fellowship in 2007-2008 as part of PDF's Career Development and Fellowships Program.  Please visit our Funding Research and Results section, to learn more about these programs and who we have funded.

Source Date: Oct 16 2008
Source Publication: Reuters Health
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