Effects of Milk Powder Intervention on Blood Glucose Control and Fluctuation in Middle-aged and Elderly People With Pre-diabetes

• fortified formula milk powder group (Dietary supplement): Fortified formula milk powder is supplemented with fiber, bitter gourd powder,mulberry leaves extract, whitekidney beans extract, and probiotics, and packaged in 25-gram sachets. The milk powder is consumed orally, two sachets per day for a duration of 8 weeks.
• regular milk powder group (Dietary supplement): Regular milk powder does not contain and additional supplementation, and the color, flavor, shape, taste, and weight are same with the formula milk powder.

Primary outcomes

• fasting blood glucose [up to 8 weeks]: At baseline, and 8 weeks, investigators will use automatic electrochemiluminescence analyzer to examine fasting blood glucose.
• 2h-piAUC after standardized breakfast [up to 8 weeks]: the positive increment of area under curve in 2 hours after standardized breakfast standardized breakfast, measured by continuous glucose monitoring at baseline, and 8 weeks.
• TIR (time in range) [up to 8 weeks]: TIR refers to the time when blood glucose is controlled within a reasonable ( target ) range (3.9\~10.0 mmol/L), measured by continuous glucose monitoring at baseline and 8 weeks.

Secondary outcomes

• HbA1c [up to 8 weeks]: At baseline, and 8 weeks, investigators will use automatic electrochemiluminescence analyzer to examine HbA1c.
• weight [up to 8 weeks]: At baseline, and 8 weeks, investigators will examine weight.
• intestinal bacteria [up to 8 weeks]: At baseline, and 8 weeks, investigators will use 16S rRNA pyrosequencing to examine intestinal bacteria.
• lipid metabolism [up to 8 weeks]: At baseline, and 8 weeks, investigators will use automatic electrochemiluminescence analyzer to examine total cholesterol, low density lipoprotein, high density lipoprotein, triglyceride.
• sleep quality [up to 8 weeks]: At baseline, and 8 weeks, investigators will use the Pittsburgh sleep quality index scale to examine sleep quality.
• blood pressure [up to 8 weeks]: At baseline, and 8 weeks, investigators will test the systolic blood pressure and diastolic blood pressure using automatic digital blood pressure monitor
• Continuous Glucose Monitoring (CGM) Data [up to 8 weeks]: At baseline, and 8 weeks, investigators will using Continuous Glucose Monitoring (CGM) to monitor the glucose level of participants

Sex: All, ages: 40 Years to 75 Years, accepts healthy volunteers

Inclusion Criteria:

1. Age between 40 and 75 years, regardless of gender.
2. Impaired fasting glucose (5.6 mmol/L ≤ FPG < 6.9 mmol/L) or glycated hemoglobin (HbA1c) between 5.7-6.4% (39-47 mmol/mol).
3. Resided in Guangzhou for the past six months and no plans to relocate or travel outside the city in the next month.
4. Signed informed consent form and voluntarily agreed to participate in the project.

Exclusion Criteria:

1. Patients with a confirmed diagnosis of diabetes who are currently taking glucose-lowering medications (e.g., insulin, GLP-1 receptor agonists, or SGLT2 inhibitors).
2. Individuals with lactose intolerance or dairy product intolerance.
3. Pregnant, planning to become pregnant within the next three months, or currently breastfeeding.
4. Weight change > 5% in the past three months or plans to lose weight or change dietary habits.
5. Alcohol consumption > 40g/day.
6. Individuals with communication barriers, cognitive impairments, or other conditions that may prevent them from completing the study procedures.
7. Severe diseases that may affect participation in the study, including but not limited to endocrine disorders, severe cardiovascular or cerebrovascular diseases, cancer, metabolic diseases, etc.
8. Participation in or current involvement in other clinical trials within the past three months.
9. No use of antibiotic medications within the past three months.