Chronotherapeutic Optimization of Teriparatide Administration in Postmenopausal Osteoporosis

Inclusion Criteria: 1. Aged 60-70 years (inclusive). 2. Naturally postmenopausal women with≥5 years since last menses. 3. DXA-measured BMD T-score≤-3.0 at lumbar spine (L1-L4) and/or total hip at screening. 4. The concentration of 25-hydroxyvitamin D (25-OH)D is ≥20 ng/ml. If the subject meets all other inclusion and exclusion criteria, it is allowed to retest the 25-OHD concentration after administering vitamin D to the subject. 5. Normal-range serum parameters: Intact PTH: 15-65 pg/mL Total calcium: 2.20-2.70 mmol/L. Exclusion Criteria: 1. Subjects with bone metabolic diseases besides osteoporosis: 1. Other metabolic bone diseases, such as osteomalacia, osteogenesis imperfecta, Paget's disease； 2. Cushing's syndrome; 3. Hyperprolactinemia; 2. Use of medications that affect bone metabolism before screening: Use of intravenous bisphosphonates, fluoride, or strontium within 2 years; Use of teriparatide or denosumab for osteoporosis within 6 months; Oral bisphosphonates for osteoporosis with the last dose within 1 year (if used within 1 year but with a cumulative use of ≤1 month, the subject is eligible); Continuous use of calcitonin for more than 3 months with the last dose within 1 year. 3. History of malignancy within 5 years, or bone metastasis, except for tumors that are expected to be cured after treatment (such as completely resected in situ basal cell or squamous cell carcinoma of the skin, cervical cancer, or breast ductal carcinoma, etc.). 4. Hypocalcemia and hypercalcemia. 5. Elevated alkaline phosphatase of unknown cause. 6. History of fractures. 7. Uncontrolled comorbidities, including heart failure with New York Heart Association (NYHA) functional class III or above, glycated hemoglobin \>8.5%, and severe arrhythmias. 8. Allergy to teriparatide. 9. Currently participating in another drug clinical trial. 10. Subjects deemed unsuitable for enrollment in this study by the investigator.