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.