An interventional study of Early (7:00 - 16:00) TRE and Mid (9:30 - 18:30) TRE in Diabetes Mellitus, Type 2, Obesity and Prediabetic State, sponsored by University of Toronto. Recruiting at 1 site in Canada. Open to participants aged 40 Years and older. Per ClinicalTrials.gov, last updated 2026-06-30.
Sponsored by University of Toronto · Not applicable, Interventional, and Treatment
This study will evaluate the effectiveness of time-restricted eating (TRE), which is a form of intermittent fasting. When performing TRE, individuals consume all of their calories within a specific time window and then only consume water or other no calorie drinks the rest of the day. TRE is performed each day. There is no restriction on the quality or amount of food that people can consume during their eating window (ad libitum eating) with TRE, which can last anywhere from 4 to 12 hours. We are comparing three different 9-hour eating windows to determine whether the start and stop time of the eating window impact blood sugar control in individuals with obesity who also have or are at risk for type 2 diabetes. We also aim to determine if there are differences in the effects of the timing of eating window between males and females.
The overarching aim of this study is to evaluate the interactions between TRE window timing, type 2 diabetes status, and sex among individuals with obesity. The first objective is to compare the effects of three 9-h TRE window times (early: 7:00-16:00 h, mid: 9:30-18:30 h, delayed: 12:00-21:00 h) on real-time, free-living glycemic control. The second objective is to determine if type 2 diabetes status (type 2 diabetes versus prediabetes or moderate+ risk for type 2 diabetes aka at risk for type 2 diabetes) modifies the effect of eating window timing on glycemic control outcomes. The exploratory objectives include: 1) determine whether sex modifies TRE adherence or the effect of TRE on metabolic changes relative to control; and 2) to compare changes in dietary intake, body weight, and blood pressure within and between early, mid, and delayed TRE. We have the following hypotheses related to these objectives:
10,371 studies on the registry are indexed under Diabetes Mellitus, Type 2; 1,406 are open to participants now.
This study's planned enrollment of 123 is above the median of 80 across 8,350 interventional studies indexed under Diabetes Mellitus, Type 2.
Browse Diabetes Mellitus, Type 2 studies →University of Toronto is the lead sponsor of 403 studies on the registry; 54 are open to participants now.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
The following exclusion criteria applies to all potential participants:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HbA1c
A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will be asked to eat ad libitum between the hours of 7:00 - 16:00 each day for seven days, and then only drink water or other no calorie beverages for the rest of the day. On the 8th day, they will consume one meal replacement beverage at 7:00 and be instructed to not consume anything else for two hours. After the two hours they will be instructed to return to their normal baseline eating habits.
Behavioral: Early (7:00 - 16:00) TRE
Participants will be asked to eat ad libitum between the hours of 9:30 - 18:30 each day for seven days, and then only drink water or other no calorie beverages for the rest of the day. On the 8th day, they will consume one meal replacement beverage at 9:30 and be instructed to not consume anything else for two hours. After the two hours they will be instructed to return to their normal baseline eating habits.
Behavioral: Mid (9:30 - 18:30) TRE
Participants will be asked to eat ad libitum between the hours of 12:00 - 21:00 each day for seven days, and then only drink water or other no calorie beverages for the rest of the day. On the 8th day, they will consume one meal replacement beverage at 12:00 and be instructed to not consume anything else for two hours. After the two hours they will be instructed to return to their normal baseline eating habits.
Behavioral: Late (12:00 - 21:00) TRE
During the first week of the study, participants will be asked to eat as they normally do, and to not make any changes regarding when they are stopping or starting eating.
A standardized TRE Protocol where participants eat ad libitum between the hours of 7:00 to 16:00 for 7 days. On the 8th day, they will consume a meal replacement beverage at 7:00, and not consume anything else for two hours.
A standardized TRE Protocol where participants eat ad libitum between the hours of 9:30 to 18:30 for 7 days. On the 8th day, they will consume a meal replacement beverage at 9:30, and not consume anything else for two hours.
A standardized TRE Protocol where participants eat ad libitum between the hours of 12:00 to 21:00 for 7 days. On the 8th day, they will consume a meal replacement beverage at 12:00, and not consume anything else for two hours.
Average 24-hour glucose total area under the curve (AUC) over 7 days
Assessed for 7 continuous days using a continuous glucose monitor.
Time frame: 7 days
Average 24-hour glucose over 7 days
Assessed for 7 continuous days using a continuous glucose monitor.
Time frame: 7 days
Average daily nocturnal glucose over 7 evenings
Assessed for 7 continuous evenings based on the sleep period identified by the Fitbit tracker using a continuous glucose monitor.
Time frame: 7 days
Average daily time spent in hyperglycemia over 7 days
The average number of hours with glucose \>10 mmol/L over 7 continuous days assessed with a continuous glucose monitor.
Time frame: 7 days
Postprandial glucose
Assessed on the morning after the 7th day of each TRE protocol. Participants will consume a standardized breakfast at a specified time, and glucose will be evaluated via continuous glucose monitor from the time they start consuming the breakfast for 2 hours.
Time frame: 2 hours
Glycemic viability
The average of each standard metrics of glycemic viability (standard deviation, coefficient of variation, mean amplitude of glycemic exercise, and continuous overall net glycemic action) will be calculated over 7 continuous days from continuous glucose monitors.
Time frame: 7 days
Patient acceptability
Patient acceptability will be assessed based on researcher-developed questions related to their experience with each TRE protocol.
Time frame: 7 days
TRE fasting duration adherence
Participants will receive twice daily text messages asking what time they started and stopped eating that day, which will be used to calculate the length of the fast each day. Adherence will be calculated as the % of days where the participant fasted for 15h or longer.
Time frame: 7 days
TRE fasting window adherence
The proportion of days where participants began and ended their meal within 15 min or 30 min of their prescribed time.
Time frame: 7 days
Dietary intake
Participants will complete the ASA-24 at baseline, and during each of the intervention periods to assess changes in macro and micronutrient composition of their diet.
Time frame: 7 days
Weight change
Participants will be asked to weigh themselves first thing in the morning, with minimal and no clothing on, after they have emptied their bowels once during the baseline period and on the last day of each of the intervention period.
Time frame: 7 days
Blood pressure change
Participants will be asked to measure their blood pressure once during the baseline period, and on the last day of each intervention period.
Time frame: 7 days
Physical Activity
Participants will be asked to wear a Fitbit for the duration of the study. We will average the amount of physical activity over 7 days of wear.
Time frame: 7 days
Sleep
Participants will be asked to wear a Fitbit for the duration of the study. We will average the amount of sleep over 7 days of wear.
Time frame: 7 days
Safety and Adverse Events
Participants will be given access to a questionnaire to report any symptoms throughout the intervention. We will compare the proportion of individuals who report these symptoms within each time period.
Time frame: 7 days
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