Association between leptin, lipid metabolism, and bone remodeling markers in men with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is associated with disturbances in bone metabolism that may increase fracture risk, even in the presence of normal or high bone mineral density (BMD). Dyslipidemia and elevated leptin levels, both common in T2DM, considered potential contributors to impaired bone remodeling, particularly in men, where skeletal responses to metabolic disturbances remain insufficiently understood. Aim. To evaluate associations between serum leptin levels, lipid metabolism parameters, and markers of bone turnover in men with T2DM. Materials and methods. A cross-sectional study included 62 men with T2DM (aged 50–65 years) and 58 age-matched non-diabetic controls. Laboratory assessments included HbA1c, insulin, leptin, testosterone, 25-hydroxyvitamin D (25(OH)D), parathyroid hormone, lipid profile, and bone turnover markers (P1NP, β-CTX). BMD at the lumbar spine and proximal femur was measured by dual X-ray absorptiometry (DXA). Insulin resistance was evaluated using HOMA-IR. Correlations were analyzed using Spearman’s rank test. Results. Men with T2DM had higher BMI (29.8 kg/m2 vs. 26.7 kg/m2, p = 0.006), elevated leptin (15.2 ng/mL vs. 11.2 ng/mL, p = 0.003), dyslipidemia (increased triglycerides and LDL-C, decreased HDL-C), and lower 25(OH)D levels (16.8 ng/mL vs. 21.6 ng/mL, p = 0.007) compared to controls. Bone formation marker P1NP was significantly reduced (35.4 ng/mL vs. 43.9 ng/mL, p = 0.009), while resorption marker β-CTX was increased (0.44 ng/mL vs. 0.37 ng/mL, p = 0.042) in T2DM group. BMD was significantly lower at the lumbar spine and total hip (p < 0.05). Leptin levels were correlated positively with BMI and HOMA-IR, while triglycerides were negatively correlated with P1NP (r = -0.218, p = 0.023). Conclusions. This study demonstrates that men with T2DM exhibited significant associations between dyslipidemia, hyperleptinemia, and altered bone metabolism. These metabolic abnormalities were linked to reduced bone mineral density, most notably at the lumbar spine and proximal femur. The results suggest that lipid and hormonal imbalances may contribute to poor bone health in T2DM, highlighting the need for careful skeletal assessment and targeted preventive approaches in this group.