Association between serum total bilirubin levels, bone mineral density, and prevalence of osteoporosis in Chinese patients with type 2 diabetes

Serum bilirubin, a potent antioxidant substance, has been associated with bone mineral density (BMD) and osteoporosis. However, previous studies have produced conflicting results. Herein, this study was to compare serum total bilirubin (TBIL) within normal physiologic levels in type 2 diabetes mellitus (T2DM) patients with osteoporosis, osteopenia and control subjects, and to assessed their association with BMD and osteoporosis. A total of 923 elderly patients with T2DM (342 patients with osteoporosis, 353 patients with osteopenia and 228 control subjects) undergoing BMD measurement were enrolled. Serum TBIL levels in T2DM patients with osteoporosis and osteopenia were significantly lower than those of normal BMD subjects (11.36±3.77 vs. 11.94±4.38 vs. 13.53±5.69 μmol/L, both P < 0.01). Serum TBIL levels were positively correlated with BMD at the lumbar spine and hip (P < 0.01 or P < 0.05). Univariate regression analysis revealed that the prevalence of osteoporosis was significantly associated with serum TBIL levels [odds ratio (OR) 0.901, 95% confidence interval (CI) 0.865-0.938, P < 0.01]. Also, multivariate regression analysis revealed that higher serum TBIL levels related independently and negatively to the prevalence of osteoporosis [adjusted OR 0.926, 95% CI 0.865-0.990, P < 0.05]. Moreover, BMD at various sites markedly increased, and the prevalence of osteoporosis markedly decreased along with increasing serum TBIL quartiles (P < 0.01 or P < 0.05). Higher TBIL levels were associated with higher BMD at the lumbar spine and hip and lower risk of developing osteoporosis in T2DM patients.