Managing Comorbid Parkinson Disease, Diabetes

While complex in itself, Parkinson disease (PD) can often be accompanied by other conditions that may affect treatment efficacy or progression. In a study published in Cureus, researchers sought to examine the implications for patients with both PD and diabetes mellitus (DM), which is the most common chronic metabolic disease.

There are several similarities between PD and DM, especially the chronic nature of both conditions. “Both diseases result from a decrease in a specific substance: dopamine in PD, and insulin in DM. Besides, both disorders arise due to the destruction of particular cells, dopaminergic cells in PD, and pancreatic beta-cell in DM,” expanded researchers.

Moreover, researchers noted that recent epidemiological and experimental studies have exhibited a connection between DM and PD, in which common underlying mechanisms, such as mitochondrial dysfunction, oxidative stress, hyperglycemia, and inflammation, are present in the pathophysiology of both diseases.

Utilizing the PubMed database, they conducted a literature review of 39 studies selected after screening for eligibility.

In their analysis, researchers note that most of the studies demonstrated an increased risk of PD in patients with DM. Notably, a study, “Association Between Diabetes and Subsequent Parkinson Disease,” reported a 32% increased incidence rate of PD in patients with type 2 DM (hazard ratio, 1.32; 95% CI, 1.29-1.35; P < .001).

Additionally, DM was found to potentially affect cognition in patients with PD, as a study by Ong et al found atrophy in different parts of the brain, including grey matter, amygdala, temporal white matter, and frontal white matter, of patients with both conditions when compared with patients with solely PD.

In examining how therapies for DM may impact pathological pathways and the progression of PD, insulin was found to play an essential role in the protection of neuron cells during neuronal development. These benefits were additionally observed when assessing glucagon like peptide-1 agonists, in which many studies showed improvement in the motor symptoms of PD and other neurodegenerative diseases after use of these DM therapies.

“In the future, further experimental and expanded clinical studies are needed to fully understand the exact pathophysiological connections between the two disorders and the efficacy of insulin and other anti-diabetic drugs in the treatment of PD in diabetic patients,” concluded researchers. “Fully understanding and targeting these pathophysiological and molecular links could result in de novo curative therapy for PD and DM.”

Reference

Hassan A, Kandel RS, Mishra R, et al. Diabetes mellitus and Parkinson disease: shared pathophysiological links and possible therapeutic implications. Cureus. Published online August 18, 2020. doi:10.7759/cureus.9853