Eating window timing to improve blood sugar in adults with obesity and type 2 diabetes or at risk
The Impact of Time-restricted Eating, Window Timing, Type 2 Diabetes Status and Sex on Glycemic Control
This study tests whether eating only during one of three nine-hour daily windows can improve blood sugar control in adults with obesity who have or are at risk for type 2 diabetes.
Quick facts
| Phase | Not applicable |
|---|---|
| Study type | Interventional |
| Enrollment | 120 (estimated) |
| Ages | 18 Years and up |
| Sex | All |
| Sponsor | University of Toronto Academic / other |
| Locations | 1 site (Toronto, Ontario) |
| Trial ID | NCT06118931 on ClinicalTrials.gov |
What this trial studies
Adults with obesity and either diagnosed type 2 diabetes (meeting the study medication and A1c limits) or at high risk for diabetes will be assigned to one of three nine-hour time-restricted eating (TRE) windows: early (7:00–16:00), mid (9:30–18:30), or late (12:00–21:00), and followed remotely across Ontario. Participants will eat ad libitum within their assigned window each day while wearing continuous glucose monitors and using smartphone-connected devices to capture real-time, free-living glycemic data. The trial will compare glycemic control between windows, test whether effects differ by diabetes status, and explore sex differences in adherence and metabolic responses. Secondary outcomes include changes in dietary intake, body weight, and blood pressure.
Who should consider this trial
Good fit: Adults over 18 with BMI 30–50 kg/m2 who have type 2 diabetes (within the study's medication and A1c limits) or are at high risk for diabetes, own a Bluetooth-capable smartphone, and are willing to restrict eating to a prescribed nine-hour window are ideal candidates.
Not a fit: People who use insulin or sulfonylureas, have recent major weight loss or bariatric surgery, take prescription weight-loss drugs, cannot change their eating window, exceed the study's weight limits, or live outside Ontario are unlikely to benefit or be eligible.
Why it matters
Potential benefit: If successful, the results could identify which daily eating window best improves blood sugar and help tailor simple meal-timing guidance for people with obesity and diabetes or prediabetes.
How similar studies have performed: Previous small TRE trials, especially with early windows, have shown mixed but promising improvements in glucose control and weight, though head-to-head comparisons of different window timings are limited.
Eligibility criteria
Show full inclusion / exclusion criteria
Inclusion Criteria: * Aged \>18 years * Body mass index \>30 kg/m2 and \<50 kg/m2 * Have access to an Apple or Android cellphone with Bluetooth. * Have type 2 diabetes or be at risk for type 2 diabetes (defined as high (33+) Canadian Diabetes Risk Score) Exclusion Criteria: * Individuals with type 2 diabetes will be excluded if: (1) currently on \>3 monotherapies for diabetes, (2) have had diabetes therapy dosage changes \<3 months, (3) self-reported hemoglobin A1c \>9.0%, (4) taking exogenous insulin, or (5) taking sulfonylureas * The following exclusion criteria applies to all potential participants: 1. History of or referral for bariatric surgery 2. Weight loss \>5% in the last 3 months 3. Taking antiobesity (weight loss) medications 4. Body weight \>340lbs 5. Diagnosed cognitive disorder that precludes them from giving consent 6. Inability or unwillingness to change their eating window to follow those prescribed in the study 7. Currently eating during \<12 hour period on 5 or more days/week 8. Physician-diagnosed eating disorder
Where this trial is running
Toronto, Ontario
- Remote Ontario-wide — Toronto, Ontario, Canada (Recruiting)
Study contacts
- Principal investigator: Amy A. Kirkham, PhD — University of Toronto
- Study coordinator: Amy A Kirkham, PhD
- Email: amy.kirkham@utoronto.ca
- Phone: 416-946-4069
How to participate
- Review the eligibility criteria above with your treating physician.
- Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
- Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.