Safety and Efficacy of Liraglutide in Parkinson's Disease

Inclusion Criteria: * Diagnosis of idiopathic PD according to the United Kingdom Parkinson's Disease Society Brain Bank (UKPDSBB) criteria for at least 2 years * Responsive to levodopa or dopaminergic treatment * Male or female between 25 and 85 years of age at time of enrollment * Women of child-bearing potential (WOCBP) must agree to use a reliable method of contraception (e.g., oral contraceptive or long-term injectable or implantable hormonal contraceptive, double barrier methods (such as condom plus diaphragm, condom plus spermicide foam, condom plus sponge), or intra-uterine devices) throughout the duration of the trial period and must have a negative serum pregnancy test at screening * Male patients with female partners who have child bearing potential must agree to use adequate contraception throughout the duration of the trial period * Capacity to give informed consent * Ability to self-administer, or to arrange a care partner to administer trial drug, to comply with trial protocol, and to attend necessary clinic visits off medication Exclusion Criteria: * Diagnosis or suspicion of other causes for Parkinsonism, including drug- or toxin-induced parkinsonism and other neurodegenerative conditions, including multiple system atrophy, progressive supranuclear palsy, Huntington's disease, Wilson's disease, or Alzheimer's disease * Active treatment with anticholinergic medications (e.g., trihexyphenidyl, tricyclic antidepressants) * Known abnormality on CT or MRI brain imaging considered to cause symptoms or signs of neurological dysfunction, or considered likely to compromise compliance with trial protocol * Concurrent dementia defined by a score lower than 120 on the MADRS-2 and/or inability to complete scale per neuropsychologist discretion * Concurrent severe depression defined by a score greater than 29 on the Beck Depression Inventory * Prior intracerebral surgical intervention for PD, including deep brain stimulation, lesional surgery, growth factor administration, gene therapy, or cell transplant * Already actively participating in a trial of a device, drug, or surgical treatment for PD, or trial participation within 30 days prior to the baseline visit * Diagnosis of diabetes mellitus of any type, established historically or by: * Fasting plasma glucose levels equal or above 126 mg/dl * Hemoglobin A1c equal or above 6.5% * Active treatment with oral antidiabetic medications * History of severe cardiac disease (e.g., angina, myocardial infarction, or cardiac surgery) in the preceding year * Significant systemic illness likely to result in deterioration of the patient's condition or, in the Investigator's opinion, affect the patient's safety during the study, including in particular: 1. History of pancreatitis 2. Personal or family history of medullary thyroid carcinoma 3. History of multiple endocrine neoplasia syndrome type 2 4. History of alcoholism 5. Severe gastrointestinal disease, including gastroparesis 6. Treatment with immunosuppressive medications (e.g., systemic corticosteroids) within the last 90 days or chemotherapeutic agents for malignancy within the last 2 years 7. Severe renal insufficiency (CrCl \<30) 8. Moderate or severe hepatic impairment 9. Severe hypertriglyceridemia (triglycerides \>500 mg/dl) * Females who are pregnant or breast feeding * Prior serious hypersensitivity reaction to Victoza or any of the product components 10) Body Mass Index \<18.5