Examining the Effects of Morning and Evening Exercise on Glucose Regulation in Adults With Prediabetes
Purpose of the Study: This study is to learn more about how exercising at different times of the day (morning versus evening) affects metabolism of glucose in the body, sleep, activity outside of exercise, and other factors.

Procedures:

2 screening visits to make sure you are eligible to be in the study. This will include a fasting blood draw and heart tracing (EKG).

If you are eligible, you will complete both exercise conditions in a random order. All participants in the study will complete the following separated by 3-4 weeks:

Baseline condition of NO exercise
Morning exercise for 3 days in a row
Evening exercise for 3 days in a row
You will be provided with an example diet to follow for the days you are completing the baseline and exercise conditions (three days total for each condition). This diet will be a "traditional" diet with a controlled amount of carbohydrates, protein, and fat per day. The investigators will provide you with examples of meals to eat during this time.
You will be asked questions and complete questionnaires about your health history, sleeping and awakening habits, and sleepiness levels.
You will undergo one x-ray scan to measure your level of body fat.
You will be asked to wear an activity monitor and sleep monitor for 6 days in a row three times during this study.
You will be asked to wear a continuous glucose monitor (CGM) for 6 days in a row three times during this study.
You will be asked to measure your saliva melatonin levels three times in the study. This will be done once per hour for 5 hours (a total of 6 saliva samples).
You will be asked to complete a procedure called a "hyperinsulinemic-euglycemic clamp" where you will have an IV placed and insulin and glucose infused with frequent lab and finger stick blood sugars monitored closely. This will be done 3 times during the study.
- EligibilityCriteria: Inclusion Criteria:  Age 20-40 years. Biologically female participants with regular menstruation Body mass index (BMI) ≥ 30.0 to ≤ 40.0 kg/m2 Prediabetes as defined by the American Diabetes Association (HgbA1c ≥ 5.7% to < 6.5% or fasting glucose ≥ 100 to < 126 mg/dL) Physically inactive (< 100 min/wk of regular exercise) No contraindications to exercise or limitations on ability to be physically active Weight stable (weight change < 5kg in past 3 months) Not currently pregnant or lactating, not pregnant within the past 6 months or planning to become pregnant in the next 6 months.  Exclusion Criteria:  History or symptoms suggestive of cardiovascular disease or congestive heart failure Diastolic blood pressure > 100 mmHg, systolic blood pressure > 160 mmHg, or resting heart rate > 100 bpm History of type 1 or type 2 DM (or fasting glucose ≥126 mg/dL or Hemoglobin A1C ≥6.5% on screening labs) Current use of medications that effect SI (oral steroids, metformin, GLP1 receptor agonists, etc). Chronic kidney disease (CKD, stage 4 or higher) TSH, electrolytes, hematocrit, white blood cell count, or platelets significantly outside the normal reference range on screening labs Triglycerides > 400 or LDL > 200 on screening labs Clinically significant abnormality on resting ECG, presence, or history of any other metabolic or chronic health problems which would affect appetite, food intake, energy metabolism, or ability to participate in exercise, History of obstructive sleep apnea, primary insomnia, night-time shiftwork, rotating work, or other atypical sleep patterns. Current or recent (within 1 month) zero or very low carbohydrate diet (< 10% daily calories from carbohydrates). - HealthyVolunteers: No - Gender: All - MinimumAge: 20 Years - MaximumAge: 40 Years - StdAgeList: Adult