SENSILINS: Impact of Cephalic Phase Insulin Release Induced by an Environmental Food Odor Stimulus on Glucose Homeostasis According to Insulin Sensitivity Level

Starting soon · Not applicable

Conditions studied: Obesity & Overweight, Insulin Resistance Syndrome

In brief

This single-center, randomized, single-blind, 2-period crossover interventional study will evaluate whether exposure to a pleasant food odor 10 minutes before a 75 g oral glucose tolerance test (OGTT) modifies glucose homeostasis in adults with different metabolic phenotypes. Participants will undergo two experimental conditions in random order: food odor stimulation and control condition without odor, separated by a 4-week washout. The main objective is to quantify the within-subject effect of food odor stimulation on the incremental area under the glucose curve (iAUC) from 0 to 120 minutes during OGTT and to assess whether this effect differs according to metabolic status. Two predefined groups will be enrolled: adults without overweight and without insulin resistance, and adults with class I obesity and low-to-moderate insulin resistance. Secondary objectives include characterization of cephalic phase insulin release (CPIR), C-peptide and GLP-1 responses, glycemic kinetics, associations between CPIR and metabolic responses, and participant acceptability of the test environment and olfactory stimulation. A plasma biobank will be constituted from part of the collected samples for future research.

Key facts

Study ID

NCT07638111

Run by

Hospices Civils de Lyon

People needed

20

Starts

2026-06-01

Expected to finish

2027-07-01

Last updated by the study team

2026-06-10

Who can join

Age: 18 and older, up to 50. Sex: any. Healthy volunteers: accepted.

You may qualify if…

• Age 18 to 50 years inclusive
• Stable body weight during the previous 3 months (±5% of total body weight)
• Willing to comply with the full study protocol
• Sedentary lifestyle or stable regular physical activity, with agreement to keep this unchanged throughout the study
• Able to understand study information, read and write French, and provide written informed consent
• Affiliated with a social security scheme or equivalent
• Non-smoker and non-vaper
• Willing not to take dietary supplements, probiotics, prebiotics, or laxatives for 10 days before each visit
• For women of childbearing potential: negative serum pregnancy test; not pregnant and not breastfeeding
• Mean score between 1 and 2 on the 3 specific CiTAS questionnaire statements used as inclusion criteria
• ETOC flash olfactory screening: able to detect the odor-containing vial among 4 presented vials for all 7 odors tested
• Able to identify the madeleine odor used in the study
• Rated pleasantness/appetence of the madeleine odor above 1/9
• For the no-overweight group: BMI 19 to <25 kg/m² and HOMA-IR <1.7
• For the obesity group: BMI 30 to <35 kg/m² and low-to-moderate insulin resistance based on HOMA-IR [protocol inconsistency to resolve; see note below]

You may not qualify if…

• Unstable medical or psychological conditions that could impair compliance, safety, or study participation in the investigator's judgment
• Alcohol consumption >30 g/day, or established abuse/dependence on another drug
• Ongoing exclusion period from another study listed in the national volunteer file
• Legal protection measure (guardianship/curatorship)
• Deprivation of liberty by judicial or administrative decision
• Exceeded annual compensation limit for research participation
• Lack of valid required health documentation in the event of exceptional governmental epidemic measures
• Blood donation within 2 months before inclusion visit
• Limited venous access making repeated blood sampling/catheter placement difficult
• Current or permanent anosmia or olfactory disorder
• Type 1 or type 2 diabetes, treated or untreated
• History of gestational diabetes
• Known or treated hypertension
• Blood pressure >160 [unit missing; likely mmHg systolic threshold]
• Dyslipidemia, treated or untreated
• Triglycerides >3 mmol/L
• Allergic rhinitis
• Nasosinusal polyposis
• History of intestinal or abdominal surgery except appendectomy or simple hernia repair
• History of ENT or neurological surgery
• Severe eating disorder (for example anorexia, bulimia, binge-eating disorder, night eating)
• Any pathology detected on clinical examination or medical interview judged by the investigator to interfere with study endpoints or participant safety
• Any biological abnormality judged by the investigator to interfere with study endpoints or participant safety
• Use of treatments likely to interfere with study measurements, for example antidepressants, antiepileptics, neuroleptics, CPAP treatment for sleep apnea, nasal spray medications, or anti-obesity drug treatment, according to investigator judgment

Where it is running

• Centre de Recherche en Nutrition Humaine Rhône-Alpes, Centre Hospitalier Lyon Sud — Pierre-Bénite, France

Full record on ClinicalTrials.gov

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