Glucose Metabolism Disorders and Parkinson's Disease: Coincidence or Indicator of Dysautonomia?

Background: Parkinson's disease (PD) and type 2 diabetes mellitus (T2DM) are both age-related diseases. Evidence from recent studies suggests a link between them. The existence of an interaction between autonomic nervous system dysfunction and the dysregulation of glucose metabolism is one of the proposed mechanisms to explain the complicated relationship between these diseases. The aims of this study are to assess the incidence of glycemic dysregulation in people with PD and to identify clinical factors that may predispose patients with PD to the occurrence of metabolic disturbances. Methods: In total, 35 individuals diagnosed with PD and 20 healthy control subjects matched in terms of age and gender participated in a study consisting of clinical and biometric assessments along with 14 days of continuous glucose monitoring (CGM) using the Freestyle Libre system. In the group of patients with PD, a comparative analysis was performed between patients with and without autonomic dysfunction. The severity of autonomic dysfunction was assessed using the SCOPA-AUT. Results: Participants diagnosed with PD demonstrated a trend toward lower morning glucose levels compared to the control group. PD patients with autonomic symptoms had greater glucose variability and a deeper trend toward lower glucose levels in the mornings. The presence of autonomic dysfunction, especially orthostatic hypotension and micturition disturbance, and the severity of autonomic symptoms were associated with greater glycemic variability. Conclusions: The occurrence of autonomic disorders in the course of Parkinson's disease predisposes patients to more profound glycemic dysregulation.