Effects of Diet and Exercise on Circadian Glycemia
- Conditions
- Glucose Intolerance
- Registration Number
- NCT03922685
- Lead Sponsor
- University of Michigan
- Brief Summary
Specific aims of the study are:
1. to evaluate whether a 24-h exposure to a 25%-carbohydrate diet will reduce postprandial glycemia to the same extent in the evening (19 h) as in the morning (7 h),. and
2. to determine whether one hour of post-meal moderate intensity exercise (at 50% of maximal effort) will further reduce postprandial glycemia.
The outcome measures are: plasma concentrations of glucose, insulin, glucose-dependent-insulinotropic peptide (GIP), leptin, and the ketone body beta-hydroxybutyrate.
- Detailed Description
The two hypotheses in this study are:
1. A 24-h exposure to a 25%-carbohydrate diet will reduce postprandial glycemia to the same extent in the evening (19 h) as in the morning (7 h), and
2. One hour of moderate-intensity exercise (at 50% of maximal effort) will further reduce postprandial glycemia to the same extent in the evening (19 h) as in the morning (7 h).
Eight postmenopausal subjects (age 58.5 years, BMI 25.6 kg/m2) participated in 4 24-h long crossover trials, two terminating at 7h and the other 2 at 19h. At each circadian time one trial required 60 minutes of moderate-intensity exercise (50% of maximal effort), and the other two involved no exercise.
Three 25%-carbohydrate meals prepared by the Michigan Clinical Research Unit (MCRU) kitchen, were eaten at subjects' home, and the fourth was eaten 20 minutes after subjects' arrival at MCRU at either 19 h or 7 h. Blood was collected from antecubital catheter at 10-minute intervals until 23:20 h or 11:20 h, respectively.Plasma was treated with protease inhibitor to preserve GIP, frozen at -80o C until glucose measurements by glucose oxidase, hormone measurements by chemiluminescence, and ketone measurements by Abbott meter strips.
Exercise intensity was determined before the exercise trials on a treadmill from oxygen consumption (VO2) and carbon dioxide production (VCO2) by subjects walking on a treadmill at 3 mph with the treadmill slope increased by 2% every 3 minutes. Maximal effort was established when respiratory exchange ratio (VCO2/VO2) reached or exceeded 1. The treadmill speed and slope at half maximal effort was used during the one-hour exercise bout which was initiated 40 minutes after the start of the meal.
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- Female
- Target Recruitment
- 8
- postmenopausal
- normal blood glucose
- no cholesterol medication
- age between 50 an 65 years
- overweight but not obese
- BMI between 25 and 30 kg/m2
- weight-stable during past 6 months
- exercise less than 20 minutes three times a week
- metabolic disease other than hormonally-corrected hypothyroidism
- musculo-skeletal disability that would preclude exercise
- smoker
- do not meet inclusion criteria
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- CROSSOVER
- Primary Outcome Measures
Name Time Method Postprandial glucose concentration Four hours: 19:20 to 23:20 in the evening trials; 7:20 to 11:20 in the morning trials The area under the postprandial glucose curve
Postprandial insulin concentration Four hours: 19:20 to 23:20 in the evening trials; 7:20 to 11:20 in the morning trials The area under the postprandial insulin curve
- Secondary Outcome Measures
Name Time Method Postprandial leptin concentration Four hours: 19:20 to 23:20 in the evening trials; 7:20 to 11:20 in the morning trials The area under the leptin postprandial curve
Postprandial glucose-dependent insulinotropic peptide (GIP) concentration Four hours: 19:20 to 23:20 in the evening trials; 7:20 to 11:20 in the morning trials The area under the postprandial GIP curve
Postprandial beta-hydroxybutyrate concentration Four hours: 19:20 to 23:20 in the evening trials; 7:20 to 11:20 in the morning trials The area under the beta-hydroxybutyrate postprandial curve