Background: To investigate the association between melatonin levels and bone mineral density (BMD) in postmenopausal women with type 2 diabetes mellitus (T2DM). Methods: One hundred and ninety postmenopausal women who visited the clinic between September 2023 and September 2024 were selected and divided into 4 groups according to their disease status: the normal group (n = 45); the abnormal bone mass group (n = 43); the T2DM group (n = 46); and the T2DM with abnormal bone mass group (n = 56). Relevant glycolipid metabolism biochemical indexes, bone metabolism markers and melatonin levels were detected and statistically analyzed. Results: Comparison of melatonin levels showed that melatonin levels were significantly lower in the abnormal bone mass group, the T2DM group, and the T2DM with abnormal bone mass group 100.00 (94.00, 110.00), 99.00 (91.75, 100.25), and 92.50 (84.75, 99.00) than in the normal group 127.71 (116.23, 137.68), and melatonin levels were the lowest in the T2DM with abnormal bone mass group ( P < .01). Melatonin levels were positively correlated with both lumbar spine L1 to L4 BMD and femoral neck BMD. T2DM differed in the role of melatonin in associating with BMD at different sites. For lumbar spine L1 to L4 BMD, the mediating effect of T2DM was not significant (percentage: −8.16%, 95% CI, −90.39 to 57.00), and for femoral neck BMD, T2DM played a significant mediating role, with its effect accounting for 33.95% (95% CI, 5.38-70.00) of the total effect. Receiver operating characteristic (ROC) curve analysis showed that the area under the curve (AUC) of the operating characteristics of subjects with melatonin levels diagnosing osteoporosis (OP) was 0.942 (95% CI, 0.902-0.982). The optimal cut-off value was 124.29 pg/mL when the Jordon index was 0.571, corresponding to a sensitivity and specificity of 57.8% and 99.3%, respectively. Multiple linear regression analysis showed that a decreased melatonin level was a risk factor for decreased BMD. Conclusion: Lower serum melatonin levels in postmenopausal women with T2DM are an independent risk factor for decreased BMD, and T2DM partially mediates the protective effect of melatonin on femoral neck BMD. Serum melatonin levels have a specific diagnostic value for abnormal bone mass in postmenopausal women with T2DM.
Li et al. (Sun,) studied this question.