This single center, double-blind, placebo-controlled study will enroll 57 participants with a diagnosis of idiopathic PD. Subjects enrolled in the study will be randomized to receive once daily self-administered injections of liraglutide (1.2 or 1.8 mg, as tolerated) or placebo at the same dose range in a 2:1 study design.~Liraglutide has been approved by the Food and Drug Administration (FDA) to treat adults with Type 2 Diabetes (T2D) and to treat obesity, but it is considered investigational in this study, as it has not been approved for use in patients with PD. Liraglutide belongs to a class of medications able to stimulate receptors of glucagon-like peptide 1 (GLP-1), a naturally occurring peptide found throughout much of the brain and able to increase the incretin effect in patients with T2D, stimulating the release of insulin. Liraglutide can reduce systemic and brain insulin resistance, an abnormality that could help drive PD pathogenesis. Indeed, impaired insulin signaling in the brain can cause or exacerbate many brain pathologies and behavioral abnormalities seen in PD. Another GLP-1 agonist, named exenatide, has been evaluated in patients with PD, showing significant improvement of motor and cognitive symptoms. There is reason to believe that liraglutide may prove superior to exenatide in treating PD.~Eligible participants will be followed for up to 14 months and will be expected to complete 9 in-person visits and 2 telephone visits. The study will measure liraglutide effects on motor (assessed by changes in the MDS-UPDRS part III) and non-motor symptoms of PD (assessed by the NMSS and MDRS-2) after 52 weeks of treatment. The secondary outcomes include measures of the association between liraglutide's effects on peripheral insulin resistance, PD symptoms and safety. Collection of blood and urine samples will be obtained to monitor drug safety.
The purpose of this study is to test the efficacy and safety of liraglutide in the treatment of patients with idiopathic Parkinson's disease (PD).