Personalized Meal Timing and Walking Based on Glucose Patterns in Adults With Prediabetes

Inclusion Criteria: * Age 30 to 70 years * Prediabetes, defined as either: * HbA1c 5.7% to 6.4% within 3 months of screening, or * Fasting plasma glucose 100 to 125 mg/dL on two separate occasions * Body mass index 23 to 40 kg/m² * Owns a smartphone compatible with study applications * Willing to wear a continuous glucose monitor and wrist activity monitor during the study period * Willing to record meals using timestamped meal-photo logging * Able to provide written informed consent Exclusion Criteria: * Current or prior diagnosis of type 1 diabetes or type 2 diabetes * Use of glucose-lowering medication within the past 3 months * Use of systemic corticosteroid medication within the past 3 months * Use of prescription weight-loss medication within the past 3 months * Current shift work * Transmeridian travel across more than 2 time zones within 4 weeks before enrollment * Known untreated or unstable sleep disorder, including obstructive sleep apnea, narcolepsy, or insomnia disorder * Pregnancy, planned pregnancy, or breastfeeding * Gastrointestinal disease or surgery likely to affect nutrient absorption * Current participation in a structured dietary or exercise intervention program * Estimated glomerular filtration rate less than 60 mL/min/1.73 m² * Inability or unwillingness to comply with continuous glucose monitoring, wrist actigraphy, meal logging, or study visits