MEAL TIMING Study: Effect of Time-Restricted Feeding on 24-hour Glycemic Control, Blood Pressure, and Cardiovascular Disease Risk Factors in Adults With Prediabetes

Not Applicable

Recruiting

Interventions: Behavioral: Early TRE
Behavioral: Mid-day TRE
Behavioral: Control Schedule

Brief Summary: One in three American adults have prediabetes, and up to 70% of adults with prediabetes eventually develop type 2 diabetes. With the high cost of treating diabetes, cost-effective approaches are needed to reduce the incidence of diabetes. One new strategy may be to change when people eat. Studies in rodents suggest that a form of intermittent fasting that limits eating to a short time period each day and involves fasting for the rest of the day (time-restricted eating; TRE) improves blood sugar control and cardiovascular health. Preliminary studies suggest that TRE also improves blood sugar, weight loss, and cardiovascular health in humans. This study will be the first full-scale, controlled feeding trial to determine whether TRE can improve 24-hour blood sugar control, 24-hour blood pressure, and cardiovascular disease risk factors even when food intake is matched to the control group. This clinical trial will also determine whether the benefits of TRE depend on the time of day that people eat. Participants will be assigned to one of three groups: (1) 'Early TRE' (eat between \~8 am-3 pm), (2) 'Mid-day TRE' (eat between \~1 pm - 8 pm), or (3) Control Schedule (\~8 am - 8 pm) for 8 weeks. All food will be provided and matched between groups.

Recruitment & Eligibility

Inclusion Criteria

Aged 30-70 years old
Prediabetic as determined by HbA1c between 5.7-6.4% or fasting glucose between 100-125 mg/dl with HbA1c >= 5.1%
Fasting insulin less than 100.0 mU/l and, if HbA1c <5.7%, must also have fasting insulin >= 8.0 mU/l
BMI between 30-60 kg/m^2
Wake up at a regular time between 5-8 am

Exclusion Criteria

Been diagnosed with diabetes or on diabetes medication or any medication known to affect glucose or 24-hour rhythms in blood pressure
On weight loss medication
Change in the dosage of a chronic medication within the past 2 months
Have a clinically significant laboratory abnormality (e.g., abnormal hemoglobin levels)
Significant gastrointestinal disease, major gastrointestinal surgery, or gallstones
Significant cardiovascular, renal, cardiac, liver, lung, adrenal, or nervous system disease that might compromise the participant's safety or data validity
Evidence of cancer (other than non-melanoma skin cancer) within the last 5 years
Pregnant or breastfeeding
Diagnosed psychiatric conditions
Sleep disorder, circadian disorder, or regularly sleep less than 6 hours per night
Major change in health or medical history in the past 3 months
Currently perform overnight shift work
Regularly eat within a <10.5-hour period each day
Lost or gained more than 4% of weight in the past 2 months
Traveled more than 2 time zones away in the 2 months prior to enrolling in this study
Will travel outside the Central time zone in the 2 weeks prior to testing
Will travel more than 1 time zone away during this study
Behavioral factors or other circumstances that may make it difficult for you to follow the study requirements

Arm && Interventions

Primary Outcome Measures

Name	Time	Method
Insulin sensitivity	8 weeks	Mean value of insulin sensitivity (dl/kg/min/μU/ml) across the three identical meal tolerance tests, as measured by the Oral Minimal Model
Glucose AUCs	8 weeks	Glucose area-under-the-curve (mg/dl x hr) during each of three identical meal tolerance tests within a 24-hour period
Insulin AUC	8 weeks	Insulin area-under-the-curve (mU/l x hr) during each of three identical meal tolerance tests within a 24-hour period
Mean 24-hour glucose levels	8 weeks	Mean 24-hour glucose levels (mg/dl)
Mean 24-hour C-peptide levels	8 weeks	Mean 24-hour C-peptide levels (pmol/l). This is also a proxy for total 24-hour insulin secretion.
C-peptide AUC	8 weeks	C-peptide area-under-the-curve (pmol/l x hr) during each of three identical meal tolerance tests within a 24-hour period
Mean 24-hour insulin levels	8 weeks	Mean 24-hour insulin levels (mU/l)
Beta-cell responsivity index (a measure of beta-cell function)	8 weeks	Mean value of beta-cell responsivity across the three identical meal tolerance tests, as measured by the Oral Minimal Model
Peak glucose and mean amplitude of glycemic excursions (MAGE) glucose values	8 weeks	mg/dl

Secondary Outcome Measures

Name	Time	Method
Percentage of individuals with non-dipping blood pressure phenotypes	8 weeks
Heart Rate	8 weeks	beats per minute
High Sensitivity C-Reactive Protein (hs-CRP)	8 weeks	mg/l
Lipids	8 weeks	Total cholesterol (mg/dl), LDL cholesterol (mg/dl), HDL cholesterol (mg/dl), and triglycerides (mg/dl)
Mean 24-hour systolic and diastolic blood pressure	8 weeks	mmHg
Cortisol	8 weeks	μg/dl
Daily maximum value, minimum value, and amplitude of systolic and diastolic blood pressure	8 weeks	mmHg
8-isoprostane	8 weeks	pg/ml

Locations (1): University of Alabama at Birmingham
🇺🇸
Birmingham, Alabama, United States