Influence of Glucose on Metabolism and Clinical Symptoms of Patients With Parkinson's Disease

Inclusion Criteria: * Diagnosis of Parkinson's Disease, stage Hoehn \& Yahr 1.5-3 * Ability to pause antiparkinsonian medication in the morning without relevant impairment * Capacity to give consent (determined in doubt by two independent neurologists, MOCA ≥18) and written informed consent. * Patients are between 50 and 80 years of age, with exceptions for a maximum of 5 additional patients enrolled per group * For stratification into patients with and without sweet craving, a 3-day dietary protocol should be completed once by the patients * Group I: increased hunger for sweets. * Group II: no increased hunger for sweets. For the stratification into patients with and without increased hunger for sweets, participants are asked to answer the following questions: 1. Do you have sudden attacks of cravings for sweets? 2. Would you say that your consumption of sweet food has increased in recent years? 3. Would you describe your consumption of sugary food as increased or excessive? If one of the questions is answered with yes, participants will be assigned to group I, if all questions are answered with no, participants will be assigned to group II. Exclusion Criteria: * Other significant neurological diseases primarily affecting the central nervous system (e.g., multiple sclerosis) * Diagnosis of diabetes mellitus or prediabetes * Use of medications that affect glucose metabolism, such as antidiabetics, glucocorticoids, ciclosporin, tacrolimus, sirolimus, beta-blockers, thiazide diuretics, beta-2 adrenoreceptor agonists, theophylline, Clozapine, olanzapine, paliperidone, quetiapine, risperidone, tricyclic antidepressants, mirtazapine, mianserin, carbamazepine, gabapentin, pregabalin, valproic acid, lithium, antiretroviral drugs, statins * cardiac or brain pacemakers