Precise Eating Time to Improve Glycemic Control and Cardiometabolic Health in Prediabetes and Diabetes

Inclusion Criteria:

* Overweight or obesity (BMI 25-40 kg/m²)
* Healthy glucose metabolism (fasting glucose \<100 mg/dl and glucose after 2 hours OGTT \<140 mg/dl)
* OR impaired glucose metabolism (fasting glucose 100-125 mg/dl and/or glucose after 2 hours OGTT 140-199 mg/dl and/or HbA1c 5.7-6.4%)
* OR type 2 diabetes (according to existing medical diagnosis or fasting glucose \>126 mg/dl and/or glucose after 2 hours OGTT \>200 mg/dl and/or HbA1c ≥6.5%)
* Daily eating window ≥12 hours

Exclusion Criteria:

* Weight changes \> 5% within past 3 months
* Shift work
* Traveling across more than one time zone within one month prior to the study
* Pregnancy and breastfeeding
* Eating disorders, food intolerance/allergy to ingredients in the diet product, vegan diet, practicing time-restricted eating
* Severe chronic illnesses or other conditions that are incompatible with the planned intervention and examination program (e.g. type 1 diabetes, recent cardiovascular event, malabsorption, cancer in the last two years, etc.)
* Treatment with insulin, sulfonylureas, and GLP-1 receptor agonists, steroid use (oral, cutaneous, or parenteral), regular intake of melatonin, anticoagulation treatment that cannot be paused
* Extreme early and extreme late chronotypes