Daytime patterns of breath chemicals in people with and without diabetes
Official title: The Daytime Circadian Rhythm in Exhaled Volatile Organic Compounds in People Living Without and With Type 1 and 2 Diabetes: an Exploratory Study
Run by University of Bern · NCT05984979 · Data updated 2026-11-12
This study will test whether levels of volatile chemicals in daytime breath follow a circadian pattern in adults with or without type 1 or type 2 diabetes.
Quick facts
| Study type | Observational |
|---|---|
| Ages | 18 Years and up |
| Sex | All |
| Enrollment | 60 (estimated) |
| Sponsor | University of Bern Academic / other |
| Locations | 1 site (Bern) |
| Status | Recruiting |
| Started | August 7, 2023 |
| Main results expected | June 30, 2026 |
| Study ends | June 30, 2026 |
| Registry record updated | December 8, 2025 |
| Trial ID | NCT05984979 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
Ideal candidates are adults (≥18) who meet one of the three group criteria—no diabetes with HbA1c <6.5%, type 1 diabetes on MDI/CSII >1 year, or type 2 diabetes on oral agents or insulin—and who are non-smokers, not pregnant, and otherwise meet the health eligibility rules.
✕Probably not a fit
People who are pregnant or breastfeeding, recent smokers, have chronic lung or intestinal disease, recent antibiotic use, certain food intolerances, heavy alcohol use, or current inhaled medications are unlikely to benefit or be eligible.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
This observational study will collect repeated daytime breath samples to measure volatile organic compounds (VOCs) and identify circadian variability. Participants are divided into three cohorts—adults without diabetes (HbA1c <6.5%), adults with type 1 diabetes on MDI or CSII for over one year, and adults with type 2 diabetes on oral medication or insulin—with a planned total of 60 participants. A standardized meal is used to reduce dietary variability, and common exclusion criteria include recent smoking, chronic lung or intestinal disease, pregnancy, recent antibiotics, and certain food intolerances. Study data will be compared across groups to detect time-of-day differences in VOC profiles that could inform future biomarker work.
Why it matters
Potential benefit: If successful, this could reveal time-of-day breath markers that help monitor metabolic status or guide the timing of tests for people with diabetes.
How similar studies have gone: Prior research indicates breath VOCs can reflect metabolic and inflammatory states, but daytime circadian patterns specifically in people with diabetes are relatively under-studied.
Who can join: the full rules
Show full inclusion / exclusion criteria
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
Where it's running
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University of Bern
Bern, Switzerland Recruiting
Study contacts
- Principal investigator: Lilian Witthauer, Prof.Dr. — University of Bern
- Study coordinator: Lilian Witthauer
- Email: lilian.witthauer@unibe.ch
- Phone: +41 31 664 22 77
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How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.