Plain English - Diabetes mellitus and Parkinson disease

This is the first of our new 'Plain English' blogs on Parkinson's research. We are responding to feedback from people who said that they sometimes find it hard to know who the target audience is for our blogs. Some posts are more understandable than others! So from on the Plain English posts will aim to be just that - understandable.

Below there is an abstract from an an article recently published in Neurology journal, in which the authors explore the relationship between diabetes and Parkinson's. Some previous studies have suggested that people with diabetes are at higher risk of being diagnosed with Parkinson's in the future. But the relationship does not end there... diabetes drugs have recently been shown to be effective in reducing the symptoms of Parkinson's and may even slow down the disease. 

In this article the authors show that people with a diagnosis of diabetes have some similarities to people with Parkinson's. The brain scans of people with diabetes looked similar to people with Parkinson's, and so did the levels of certain proteins in their spinal fluid. Furthermore they show that people with both Parkinson's and diabetes, the movement and memory problems tend to progress faster than in those with just Parkinson's on its own.

Interest in the link between Parkinson's and diabetes in increasing, so these types of study are important in helping us to better understand one affects the other.

- Alastair Noyce

Gennaro Pagano, Sotirios Polychronis, Heather Wilson, Beniamino Giordano, Nicola Ferrara, Flavia Niccolini and Marios Politis
Neurology
First published April 6, 2018
DOI: https://doi.org/10.1212/WNL.0000000000005475

http://n.neurology.org/content/90/19/e1654

Objective
To investigate whether diabetes mellitus is associated with Parkinson-like pathology in people without Parkinson disease and to evaluate the effect of diabetes mellitus on markers of Parkinson pathology and clinical progression in drug-naive patients with early-stage Parkinson disease.

Methods
We compared 25 patients with Parkinson disease and diabetes mellitus to 25 without diabetes mellitus, and 14 patients with diabetes mellitus and no Parkinson disease to 14 healthy controls (people with no diabetes mellitus or Parkinson disease). The clinical diagnosis of diabetes mellitus was confirmed by 2 consecutive fasting measurements of serum glucose levels >126 mL/dL. Over a 36-month follow-up period, we then investigated in the population with Parkinson disease whether the presence of diabetes mellitus was associated with faster motor progression or cognitive decline. 

Results
The presence of diabetes mellitus was associated with higher motor scores (p < 0.01), lower striatal dopamine transporter binding (p < 0.05), and higher tau CSF levels (p < 0.05) in patients with Parkinson disease. In patients with diabetes but without Parkinson disease, the presence of diabetes mellitus was associated with lower striatal dopamine transporter binding (p < 0.05) and higher tau (p < 0.05) and α-synuclein (p < 0.05) CSF levels compared to healthy controls. At the Cox survival analysis in the population of patients with Parkinson disease, the presence of diabetes mellitus was associated with faster motor progression (hazard ratio = 4.521, 95% confidence interval = 1.468–13.926; p < 0.01) and cognitive decline (hazard ratio = 9.314, 95% confidence interval = 1.164–74.519; p < 0.05).

Conclusions
Diabetes mellitus may predispose toward a Parkinson-like pathology, and when present in patients with Parkinson disease, can induce a more aggressive phenotype.

Picture from the Shake It Up Australia Foundation 

https://shakeitup.org.au/diabetes-drug-trial-parkinsons/