Not yet recruitingNAINTERVENTIONAL

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

The SENSILINS study is investigating whether smelling pleasant food, like a madeleine, just before you eat, can affect how your body deals with sugar. Researchers believe that some smells might make your body release insulin earlier, which could help manage blood sugar levels. This study involves adults, some with healthy weight and no insulin resistance, and others with obesity and some insulin resistance. Participants will have two visits, four weeks apart. During one visit, they'll smell food before a sugar drink, and during the other, they won't. Blood samples will be taken to measure sugar levels and other hormones. The aim is to understand if smell can help improve how your body processes sugar, especially for people with different metabolic conditions.

At a glance

Status

Not yet recruiting

Phase

Sponsor

Hospices Civils de Lyon

Enrolment target

Start

01 Jun 2026

Estimated completion

01 Jul 2027

Obesity & Overweight Insulin Resistance Syndrome

What is this study about?

The SENSILINS study is exploring a fascinating idea: can simply smelling food change how your body handles sugar? You know how sometimes just the smell of delicious food can make your mouth water? That's your body getting ready to eat. Scientists think that this 'anticipation' might also make your body release a hormone called insulin even before you've taken the first bite. This early insulin release could be a natural way for your body to prepare for incoming sugar, potentially leading to better blood sugar control.

This research is important because conditions like obesity and insulin resistance (where your body doesn't use insulin as well as it should) are very common. If we can understand how senses like smell affect our metabolism, it might open up new ways to help people manage their blood sugar. The study specifically wants to see if this 'smell-induced insulin release' happens in people, and if it's different for those with and without obesity or insulin resistance.

Researchers will use a pleasant food smell, like a madeleine, to see if it triggers this early insulin release. They'll then measure how your body responds to a sugary drink. By comparing what happens when you smell the food versus when you don't, they hope to learn more about the connection between our senses, hormones, and how our bodies process food.

Key takeaways

Exploring if pleasant food smells affect blood sugar response.
Involves adults with and without obesity/insulin resistance.
Compares blood sugar changes after sugar drink with and without smell.
Requires two study visits, four weeks apart, with blood tests.
Aims to understand the brain-body connection in digestion.

Who may be eligible?

To join this study, you need to be an adult between 18 and 50 years old and have a stable weight for the past three months. You should also be able to understand the study information and be willing to follow the study's instructions.

The study is looking for two main groups of people: one group who are of a healthy weight and whose bodies respond normally to insulin, and another group who have obesity and show some signs of insulin resistance. You shouldn't smoke or vape, drink a lot of alcohol, or be taking certain supplements or laxatives close to the study visits. Women who could become pregnant will need a negative pregnancy test and must not be breastfeeding.

There are also some specific tests you'll need to pass related to your sense of smell. You'll need to be able to detect and identify a specific food smell (like a madeleine) and find it pleasant. If you have any serious ongoing medical or psychological conditions, or if you've recently donated blood, you might not be able to participate.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you between 18 and 50 years old?
Have you kept a stable weight for the last 3 months?
Are you a non-smoker and non-vaper?
Can you detect and identify a madeleine smell, and find it pleasant?
Are you able to avoid certain supplements and laxatives before visits?
Are you generally healthy, without complicated medical issues?

Answer every question to see your result.

What does participation involve?

If you decide to take part, you'll have an initial screening visit to make sure you're suitable for the study. After that, you'll have two main study visits, separated by about four weeks. These visits will be much the same, but during one, you'll be exposed to the pleasant food smell before drinking a sugary solution, and for the other, you won't smell anything before the drink. You won't know which 'condition' you're in during each visit (this is called single-blind).

During each of these main visits, blood samples will be taken multiple times, both before and after you drink the sugary solution. This helps the researchers track how your blood sugar and other hormones change over time. The total duration of your involvement will be around 4-5 weeks, including the screening and the two main experimental visits. You'll need to avoid certain supplements, probiotics, prebiotics, or laxatives for 10 days before each visit.

Potential risks and benefits

Participating in research always involves a balance. A potential benefit of this study is contributing to our understanding of how our bodies process sugar, which could eventually help in developing new strategies for managing conditions like obesity and diabetes. You won't directly receive personal medical advice or treatment. The main risks involve repeated blood sampling, which can cause minor discomfort, bruising, or rarely, infection. You'll also need to follow specific instructions, including diet restrictions before visits. You have the right to withdraw from the study at any time, for any reason, without it affecting your medical care.

Locations (1)

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

Common questions

What is 'insulin resistance'?

Insulin resistance means your body's cells don't respond as well to insulin, the hormone that helps sugar get into your cells for energy.

What is an 'OGTT'?

An OGTT, or Oral Glucose Tolerance Test, measures how well your body handles sugar by tracking your blood sugar levels after you drink a sugary drink.

Will I know if I'm smelling the food or not?

No, you won't know during the main visits if you're getting the food smell or not. This helps keep the results fair and unbiased.

What is a 'washout period'?

A washout period is a time between study visits where nothing specific happens, to make sure any effects from the previous visit have worn off.

Will I get to eat the madeleine?

No, the study only involves smelling the madeleine; you won't be eating it.

How to find out more

Anne Laure MD CASTELL, Dr

anne-laure.castell@chu-lyon.fr +33 4 78 86 19 72 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.