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

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

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.

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