Olfactory Odour Stimulation for Metabolism Control (OLFAMET)

Olfactory Odour Stimulation for Metabolism Control - the "OLFAMET-Study"

In this preliminary short-term study it is investigated, whether a short olfactory stimulation with D-Limonene leads to an acute improvement of glucose metabolism in patients with obesity.

Study Overview

• Status: Completed
• Conditions: Obesity
• Intervention / Treatment: Other: D-Limonene; Other: SLVO

• Study Type: Interventional
• Enrollment (Actual): 41
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Katharina Timper, Dr. med; Phone Number: 061 328 57 42; Email: katharina.timper@usb.ch
• Study Contact Backup: Name: Anouk Hoogkamer; Phone Number: 41 61 328 55 20; Email: anouklisa.hoogkamer@usb.ch

Study Locations

• Switzerland
  • Basel, Switzerland, 4031
    • Clinic for Intensive Care Medicine, University Hospital Basel

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age 18-70 years
• Obesity (BMI ≥35 kg/m2)
• Written informed consent
• Normosmia (defined by sniffin Sticks test)

Exclusion Criteria:

• Known allergy to D-Limonene, citrus fruits, citrus flavours, SLVO
• Regular smoking
• Current illicit drug abuse including daily marijuana and cannabidiol (CBD) consumption (alcohol ≤2 drinks per day allowed)
• Diabetes mellitus
• Pre-Treatment with insulin sensitizing drugs including GLP-1 analogues
• History of neurodegenerative diseases, severe head trauma
• Severe renal impairment (e.g. estimated glomerular filtration rate <30 ml/min/m2)
• Known liver cirrhosis or other severe liver impairment
• Acute upper respiratory tract infection
• Uncontrolled dysthyroidism
• Uncontrolled hypertension
• Regular use of psychopharmaceutic drugs
• Patient aims to start a new diet or exercise program during the study
• Bariatric surgery
• Pregnancy/Lactation
• Symptoms of menopause
• Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc.
• Participation in an interventional study within the last 3 months

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Experimental1; During the Cross-Over study, patients will be randomly assigned to one of the arms: Treatment sequence: Placebo at the baseline visit, olfactory Stimulation with D-Limonene at visit 2 and olfactory Stimulation with lavender oil (SLVO) at visit 3	Other: D-Limonene; Patient will put the aspUraclip®, a commercially available mini-inhalator filled for our study purpose filled with 1% D-Limonene in the nose for 15 minutes; Other: SLVO; Patient will put the aspUraclip®, a commercially available mini-inhalator filled for our study purpose filled with 1% SLVO in the nose for 15 minutes
Active Comparator: Experimental2; During the Cross-Over study, patients will be randomly assigned to one of the arms: Treatment sequence: Placebo at the baseline visit, olfactory Stimulation with SLVO at visit 2 and olfactory Stimulation with D-Limonene at visit 3	Other: D-Limonene; Patient will put the aspUraclip®, a commercially available mini-inhalator filled for our study purpose filled with 1% D-Limonene in the nose for 15 minutes; Other: SLVO; Patient will put the aspUraclip®, a commercially available mini-inhalator filled for our study purpose filled with 1% SLVO in the nose for 15 minutes

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change of area under blood glucose curve (AUBGC)	area under the blood glucose curve (AUBGC) during a mixed-meal test after stimulation with D-Limonene compared to baseline	Time Frame: baseline blood exam (timepoint 0) and further blood collections: 5, 15, 30, 60, 90 and 120 minutes after drinking a standardized mixed-meal solution

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
AUBGC	AUBGC during a mixed-meal test after stimulation with SLVO compared to baseline	Time Frame: baseline blood exam (timepoint 0) and further blood collections: 5, 15, 30, 60, 90 and 120 minutes after drinking a standardized mixed-meal solution
Visual Analogue Scale (VAS score)	VAS scores on hunger, appetite, nausea, mood, and hedonics of odour and/or taste of the mixed-meal shake, where 0 equals none, and 10 the maximum of each category	Time Frame: baseline VAS score (timepoint 0) and VAS scores will be evaluated after 15, 30, 60, 90 and 120 minutes after drinking a standardized mixed-meal solution
Change in plasma insulin levels	Plasma insulin levels (mIU/L)	Time Frame: baseline blood exam (timepoint 0) and further blood collections: 5, 15, 30, 60, 90 and 120 minutes after drinking a standardized mixed-meal solution
Change in plasma peak glucose levels	Plasma peak glucose levels (mmol/L)	Time Frame: baseline blood exam (timepoint 0) and further blood collections: 5, 15, 30, 60, 90 and 120 minutes after drinking a standardized mixed-meal solution
Change in plasma levels of glucagon-like peptide 1 (GLP-1)	Plasma levels of GLP-1 (pmol/L)	Time Frame: baseline blood exam (timepoint 0) and further blood collections after 5, 15, 30, 60, 90 and 120 minutes after drinking a standardized mixed-meal solution
Change in plasma levels of gastric inhibitory polypeptide (GIP)	Plasma levels of GIP (pmol/L)	Time Frame: baseline blood exam (timepoint 0) and further blood collections after 5, 15, 30, 60, 90 and 120 minutes after drinking a standardized mixed-meal solution
Change in plasma levels of Ghrelin	Plasma levels of Ghrelin (pg/ml)	Time Frame: baseline blood exam (timepoint 0) and further blood collections after 5, 15, 30, 60, 90 and 120 minutes after drinking a standardized mixed-meal solution
Change in plasma levels of Leptin	Plasma levels of Leptin (ng/ml)	Time Frame: baseline blood exam (timepoint 0) and further blood collections after 5, 15, 30, 60, 90 and 120 minutes after drinking a standardized mixed-meal solution
Change in plasma levels of Peptide YY (PYY)	Plasma levels of PYY (pg/ml)	Time Frame: baseline blood exam (timepoint 0) and further blood collections after 5, 15, 30, 60, 90 and 120 minutes after drinking a standardized mixed-meal solution
Change in plasma levels of Glucagon	Plasma levels of Glucagon (pmol/L)	Time Frame: baseline blood exam (timepoint 0) and further blood collections after 5, 15, 30, 60, 90 and 120 minutes after drinking a standardized mixed-meal solution
Change in plasma Levels of Interleukin-6	Plasma Levels of Interleukin-6 (pg/ml)	Time Frame: baseline blood exam (timepoint 0) and further blood collections after 5, 15, 30, 60, 90 and 120 minutes after drinking a standardized mixed-meal solution
Change in plasma Levels of C-reactive protein	Plasma Levels of C-reactive protein (μg/ml)	Time Frame: baseline blood exam (timepoint 0) and further blood collections after 5, 15, 30, 60, 90 and 120 minutes after drinking a standardized mixed-meal solution
Change in plasma levels of lipids like LDL-cholesterine, total cholesterine, triglycerides	Plasma levels of lipids (mmol/L) like LDL-cholesterine, total cholesterine, triglycerides	Time Frame: baseline blood exam (timepoint 0) and further blood collections: 5, 15, 30, 60, 90 and 120 minutes after drinking a standardized mixed-meal solution
Change in heart rate	Heart rate (heart beats per minute)	Blood pressure and heart rate will be measured at the following times: baseline (timepoint 0) and 30, 60, 120 minutes drinking a standardized mixed-meal solution
Change in blood pressure	blood pressure (mm Hg)	Blood pressure and heart rate will be measured at the following times: baseline (timepoint 0) and 30, 60, 120 minutes drinking a standardized mixed-meal solution

Collaborators and Investigators

• Sponsor: University Hospital, Basel, Switzerland
• Investigators: Principal Investigator: Katharina Timper, Dr. med, Endocrinology, Diabetology and Metabolism, University Hospital Basel

Study record dates

Study Major Dates

• Study Start (Actual): December 10, 2019
• Primary Completion (Actual): May 10, 2022
• Study Completion (Actual): October 13, 2022

Study Registration Dates

• First Submitted: January 7, 2020
• First Submitted That Met QC Criteria: January 7, 2020
• First Posted (Actual): January 10, 2020

Study Record Updates

• Last Update Posted (Estimated): December 6, 2023
• Last Update Submitted That Met QC Criteria: November 29, 2023
• Last Verified: November 1, 2023

More Information

Terms related to this study

• Keywords: Obesity; glucose metabolism; Olfactory stimulation; D-limonene; lavender oil (SLVO)
• Additional Relevant MeSH Terms: Overnutrition; Nutrition Disorders; Overweight; Body Weight; Obesity
• Other Study ID Numbers: 2019-01909;me19ChristCrain

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No