Intranasal Insulin and Glutathione as an Add-On Therapy in Parkinson's Disease

Key Inclusion Criteria: * Documented clinical diagnosis of idiopathic PD * Modified HY stage \< 5 * Able to administer study drug or have a caregiver throughout the duration of the study to help administer drug * Willing to continue diet, exercise and medications reported at baseline consistently throughout participation in the trial. Essential changes are permitted * If taking PD medications or any nutraceuticals, must be on a stable dose for at least 30 days prior to Screening Visit. Essential changes will be permitted. * If subject is taking chronic antidepressant or an anxiolytic, must be on a stable dose for at least 90 days prior to Screening. Essential changes will be permitted. Key Exclusion Criteria: * Clinical diagnosis of Type 1 or Type 2 Diabetes Mellitus * Glycated hemoglobin (HbA1c) level ≥ 6.5% * History of hypoglycemia and/or documented plasma glucose levels of ≤ 50 mg/dL with or without symptoms of hypoglycemia * Mini-Mental State Exam (MMSE) score of ≤ 24 at Screening * Positive COVID-19 test at Screening and/or within 30 days of Screening * Change in or escalation of dose of a chronic therapeutic agent that has the potential to impair cognitive functioning * Chronic inflammation of nasal cavity that may prevent absorption of study treatments * Insufficiently controlled respiratory disease (i.e., asthma, COPD). * History of any significant neurologic or psychiatric disease other than PD * Current diagnosis of epilepsy and had a history of seizures as an adult within 1 year of Screening, or unexplained recent loss of consciousness, or history of significant head trauma with loss of consciousness * History of non-lacunar ischemic and/or hemorrhagic stroke * Unstable or uncontrolled cardiac disease that could expose the subject to additional safety risks * Use of the following medications: Insulin or any other anti-hyperglycemic agent(s) except if used during isolated gestational diabetes, Supplementation with GSH or any medication shown to increase glutathione, and Beta Blockers