This study will implement a four-week dietary intervention among middle-aged and older adults with pre-diabetes. Participants assigned to the intervention arm will replace their usual cooking oil with diacylglycerol (DAG) oil, while those in the control arm will consume colza oil. All other lifestyle behaviors will be maintained without modification. The trial will determine the impact of DAG oil consumption on glycemic regulation, lipid metabolism, and body composition in this high-risk population.

Inclusion Criteria:

1. Aged 40-75 years.
2. Diagnosed with prediabetes according to American Diabetes Association (ADA) criteria: including fasting plasma glucose (FPG) levels of 5.6-6.9 mmol/L, and/or 2-hour postprandial glucose (OGTT-2h) levels of 7.8-11.1 mmol/L, and/or glycated hemoglobin (HbA1c) levels of 5.7%-6.4%.
3. Body mass index (BMI) ≥ 24 kg/m².
4. No plans to relocate or travel extensively in the next three months.
5. Willing to consume all study-provided meals throughout the intervention.
6. Willing and able to provide written informed consent.

Exclusion Criteria:

1. Diagnosis of diabetes (Type 1 or Type 2).
2. Current use of any glucose-lowering medication.
3. Use of appetite suppressants or hormonal medications.
4. History of bariatric surgery, or weight change >5% in the past 3 months.
5. Alcohol consumption >40 g/day.
6. Use of antibiotics, probiotics, or prebiotics within the past 3 months.
7. Pregnancy, lactation or planning pregnancy.
8. History of severe cardiovascular disease, malignancy, autoimmune disease, cognitive impairment, or severe dysfunction of thyroid, liver, kidney, or digestive system.
9. Inability to comprehend information, communicate effectively, or comply with the study protocol.