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

Many patients with Parkinson's Disease (PD) report an increased consumption of fast-acting sugars. This tendency to consume sweet, high-sugar foods occurs in some patients even before the onset of cardinal motor symptoms. Some recent studies have demonstrated that PD patients have an increased consumption of fast-acting carbohydrates compared to healthy controls. However, the reason for this change in eating behavior has not yet been adequately explained. It is discussed that the increased sugar intake leads to an increased dopamine release in the brain via an increase in insulin and thus to an improvement in clinical symptoms. This study investigates the influence of fast-acting carbohydrates on insulin and glucose blood levels as well as motor and non-motor symptoms in patients with PD using an oral glucose tolerance test and a placebo oral glucose tolerance test in a crossover design.

Study Overview

• Status: Recruiting
• Conditions: Parkinson Disease; Nutritional and Metabolic Diseases; Sugar Intake
• Intervention / Treatment: Diagnostic test: Oral Glucose Tolerance Test; Other: Placebo Oral Glucose Tolerance Test

• Study Type: Observational
• Enrollment (Estimated): 50

Contacts and Locations

• Study Contact: Name: Eva Schäffer, MD; Phone Number: 004943150023983; Email: eva.schaeffer@uksh.de
• Study Contact Backup: Name: Julienne Haas, MD; Email: julienne.haas@uksh.de

Study Locations

• Germany
  • Kiel, Germany, 24118
    • Recruiting
    • Department for Neurology, University of Kiel
    • Contact: Eva Schäffer, Dr.; Phone Number: 004943150023983; Email: eva.schaeffer@uksh.de

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Probability Sample

Study Population

The study population includes Parkinson's Disease patients with and without sweet cravings. Recruitment of patients takes place in the outpatient clinic for movement disorders at the University of Kiel.

Description

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

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
PD patients with craving for sweets	Diagnostic test: Oral Glucose Tolerance Test; Application of 82,5 g of glucose monohydrate solved in 300ml water; Other: Placebo Oral Glucose Tolerance Test; Application of 125mg sucralose solved in 300ml water
PD patients without craving for sweets	Diagnostic test: Oral Glucose Tolerance Test; Application of 82,5 g of glucose monohydrate solved in 300ml water; Other: Placebo Oral Glucose Tolerance Test; Application of 125mg sucralose solved in 300ml water

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Concentration of Insulin in µU/mL	Blood value	immediately before Application of oral glucose tolerance test and placebo as well as 30, 60, 90 and 120 minutes after application
Motor function	assessed by Unified Parkinson's Disease Rating Scale Part III, 0-132 points, higher points indicate worse motor function	immediately before Application of oral glucose tolerance test and placebo as well as 30, 60 and 120 minutes after application
Concentration of Blood Glucose in mg/dL	Blood value	immediately before Application of oral glucose tolerance test and placebo as well as 30, 60, 90 and 120 minutes after application

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cognitive function	assessed by Montreal-Cognitive-Assessment-Test (MoCa), 0-30 points, higher points indicate better cognitive function	immediately before Application of oral glucose tolerance test and placebo as well as 60 minutes after application

Collaborators and Investigators

• Sponsor: University Hospital Schleswig-Holstein
• Collaborators: University of Kiel

Study record dates

Study Major Dates

• Study Start (Actual): September 1, 2023
• Primary Completion (Estimated): December 1, 2025
• Study Completion (Estimated): December 1, 2025

Study Registration Dates

• First Submitted: July 21, 2023
• First Submitted That Met QC Criteria: August 10, 2023
• First Posted (Actual): August 21, 2023

Study Record Updates

• Last Update Posted (Actual): September 22, 2025
• Last Update Submitted That Met QC Criteria: September 16, 2025
• Last Verified: September 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Synucleinopathies; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Neurodegenerative Diseases; Movement Disorders; Parkinsonian Disorders; Basal Ganglia Diseases; Parkinson Disease; Nutritional and Metabolic Diseases; Investigative Techniques; Clinical Laboratory Techniques; Diagnostic Techniques and Procedures; Diagnosis; Blood Chemical Analysis; Clinical Chemistry Tests; Diagnostic Techniques, Endocrine; Glucose Tolerance Test
• Other Study ID Numbers: D 537/23

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No