Exercise, Chronotype, and Prediabetes

Summary

The goal of this clinical trial is to find out whether exercising at the right time of day, based on a person's natural body clock, leads to greater health benefits in people living with prediabetes. The main question it aims to answer is whether doing a single session of exercise in the morning or in the evening affects how the body handles sugar differently in adults with prediabetes who have an extreme natural body clock. This will be done by comparing three conditions (no-exercise, morning exercise, and evening exercise) within the same participant. Each condition will be tested on a different day, with at least 14 days between the test days. During the no-exercise test days, participants will come to the study centre and will only be allowed to do sedentary activities (e.g. office work, reading, or screen time). During the morning exercise test days, participants will perform an exercise session at 9:00 am that involves short periods of very hard effort followed by short rest periods. Whereas for the evening exercise test days, the same type of exercise will be performed at 5:00 pm.

Eligibility

Inclusion Criteria:

1. Able to provide signed and dated written informed consent prior to any study specific procedures
2. Adult men and women aged between more than 18 and ≤ 75 years
3. Body mass index (BMI) of 25 - 35 kg/m2
4. Stable weight (no weight loss or gain \> 3 kg in the past 3 months)
5. Pre-diabetes defined as an isolated impaired glucose tolerance or a combination of impaired glucose tolerance and impaired fasting glucose (values are based on the American Diabetes Association (ADA):

   1. impaired glucose tolerance (plasma glucose 140 mg/dL to 199 mg/dL, 120 minutes after consumption of 75g of glucose)
   2. impaired fasting glucose (fasting plasma glucose 100 mg/dL to 125 mg/dL)
6. Morning (Morningness-Eveningness Questionnaire \[MEQ\] score ≥ 59) or evening (MEQ score ≤ 41) chronotype

Exclusion Criteria:

1. Previously diagnosed with type 2 diabetes
2. Moderate to severe anemia (hemoglobin \< 10 g/L)
3. Uncontrolled hypertension
4. Abnormal electrocardiogram (ECG) at rest judged by the study physician
5. Pregnancy or breastfeeding
6. HIV, hepatitis B, or C infection
7. Disorders of blood clotting or wound healing
8. Positive history of venous thrombosis (contraindication for clamp)
9. Hypersensitivity to local anesthetics (contraindication for fat/muscle biopsies)
10. Night shift work in the last 3 months
11. Travel across \> 1 time zone in the last 3 months
12. Participation in another clinical trials that may possibly hamper the study results
13. Engagement in structured exercise activities \> 2 hours a week
14. Any acute condition, exacerbation of chronic condition, or medical history that in the investigator's opinion would interfere with the study
15. Any contraindication for MRI scanning
16. Medication use known to hamper safety during the study procedures
17. Non-German speaking

Conditions3

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