The Daytime Circadian Rhythm in Exhaled Volatile Organic Compounds in People Living Without and Diabetes (VOCircle)

The Daytime Circadian Rhythm in Exhaled Volatile Organic Compounds in People Living Without and With Type 1 and 2 Diabetes: an Exploratory Study

Exhaled volatile organic compounds will be measured during daytime with the goal to identifying circadian variability. The study incudes three subgroups: people without diabetes, people with type 1 diabetes, and people with type 2 diabetes. A total of 60 people will be recruited for the study.

Study Overview

• Status: Recruiting
• Conditions: Diabetes Mellitus
• Intervention / Treatment: Other: Standardized meal

• Study Type: Observational
• Enrollment (Estimated): 60

Contacts and Locations

• Study Contact: Name: Lilian Witthauer; Phone Number: +41 31 664 22 77; Email: lilian.witthauer@unibe.ch

Study Locations

• Switzerland
  • Bern, Switzerland, 3010
    • Recruiting
    • University of Bern
    • Contact: Witthauer Lilian, Prof.Dr.; Phone Number: +41 31 664 22 77; Email: lilian.witthauer@unibe.ch
    • Principal Investigator: Witthauer Lilian, Prof.Dr.
    • Sub-Investigator: Nicolier Cléo

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

60 participants with the following subgroups: Subgroup 1: People without diabetes Subgroup 2: People diagnosed with T1D Subgroup 3: People diagnosed with T2D

Description

Inclusion criteria

Subgroup 1:

• Age 18 or older
• HbA1c below 6.5%
• Written informed consent

Subgroup 2:

• Age 18 or older
• T1D (Type 1 diabetes) with MDI (multiple daily injection) or CSII (Continuous subcutaneous insulin infusion therapy) therapy >1 year
• Written informed consent

Subgroup 3

• Age 18 or older
• T2D (Type 2 diabetes) with oral antidiabetic medication or insulin therapy
• Written informed consent

Exclusion criteria

• Pregnancy or breastfeeding
• Smoking (last cigarette less than 6 months ago)
• Any chronical lung and intestinal disease diagnosis (such as intestinal bowel disease (IBD); asthma; COPD (chronic obstructive pulmonary disease); lung cancer, …)
• Coeliac disease
• Lactose and fructose intolerance
• Any acute disease diagnosis (such as viral or bacterial infection)
• Drinking habit of more than four units of alcohol per day
• Current inhaled medicines treatments
• Antibiotic treatment in the previous 4 months

Study Plan

How is the study designed?

Number of groups / cohorts

3

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
People without diabetes	Other: Standardized meal; The participants will receive a standardized meal for breakfast
People with type 1 diabetes	Other: Standardized meal; The participants will receive a standardized meal for breakfast
People with type 2 diabetes	Other: Standardized meal; The participants will receive a standardized meal for breakfast

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
VOC Patterns over time as gallery plots	Gallery plots (3D visualization of retention index, drift time, ion current) from selected VOC peaks over time.	During the study procedure (approximately 8 hours)
VOC Patterns over time as boxplots	Box plots from selected VOC peaks over time.	During the study procedure (approximately 8 hours)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Capillary blood glucose	Correlation between capillary blood glucose and VOCs	During the study procedure (approximately 8 hours)
Correlation between VOCs in breath intestinal microbiota	Correlation between VOCs in breath and intestinal microbiota species abundance	day 1
Correlation between VOCs in breath oral microbiota	Correlation between VOCs in breath and oral microbiota species abundance	day 1
Correlation between VOCs and subgroups	Wilcoxon signed-rank test will be used to explore if the patterns in VOCs differ between subgroup: people without diabetes, people living with T1D, and people living with T2D	day 1 or 8 hours

Collaborators and Investigators

• Sponsor: University of Bern
• Collaborators: DCB Research AG; Insel Gruppe AG, University Hospital Bern
• Investigators: Principal Investigator: Lilian Witthauer, Prof.Dr., University of Bern

Study record dates

Study Major Dates

• Study Start (Actual): August 7, 2023
• Primary Completion (Estimated): June 30, 2026
• Study Completion (Estimated): June 30, 2026

Study Registration Dates

• First Submitted: July 24, 2023
• First Submitted That Met QC Criteria: August 2, 2023
• First Posted (Actual): August 9, 2023

Study Record Updates

• Last Update Posted (Actual): December 8, 2025
• Last Update Submitted That Met QC Criteria: December 1, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Endocrine System Diseases; Metabolic Diseases; Glucose Metabolism Disorders; Nutritional and Metabolic Diseases; Diabetes Mellitus
• Other Study ID Numbers: VOCircle

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

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