Non-linear relationship between serum osteocalcin and diabetic retinopathy in postmenopausal women with type 2 diabetes mellitus.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is associated with diabetic retinopathy (DR), but effective interventions are lacking. The relationship between osteocalcin (OC) and DR in postmenopausal women with T2DM is understudied. METHODS: This study examined 950 postmenopausal women with T2DM (T2DR group: n = 299; T2DM group: n = 651). RESULTS: Significant differences (p < 0.05) were observed between the groups in disease duration, age, gender, body mass index (BMI), glycated haemoglobin (HbA1c), low-density lipoprotein (LDL-C), parathyroid hormone (PTH), total type I collagen amino acid-prolonging peptide (TPINP), OC, and 25 hydroxyvitamin D (25(OH)D3). Logistic regression revealed associations of LDL-C, PTH, and 25(OH)D3 with DR. A non-linear relationship (p < 0.05) between OC and DR was found. The lowest DR risk occurred at OC levels of 15.0-25.3 ng/ml (OR, 0.66; 95 % CI, 0.44, 0.98) compared to 11.1-15.0 ng/ml. Risk remained unchanged below 11.1 ng/ml or above 25.3 ng/ml. CONCLUSION: In conclusion, among postmenopausal women with T2DM, OC levels showed a non-linear relationship with DR. Optimal OC levels (15.0-25.3 ng/ml) were associated with minimal DR occurrence, while risk was constant below 11.1 ng/ml or above 25.3 ng/ml. Maintaining optimal OC levels may reduce DR risk in this population.