Endocrine Abstracts

Introduction: Diabetes mellitus (DM) is a risk factor for reduced bone mass. Several bone metabolic pathways seem to be disrupted in patients with type 1 diabetes mellitus (T1DM).

Materials and methods: We evaluated 40 children and adolescents with T1DM (mean±S.D., age 13.04±3.53 years, mean±S.D., T1DM duration 5.15±3.33 years) and 40 healthy age- and gender-matched controls (mean±S.D., age 12.99±3.3 years). Osteoprotegerin (OPG), receptor activator of nuclear factor-κB ligand (s-RANKL), osteocalcin, C-telopeptide crosslinks-CTX, electrolytes, PTH, total 25(OH)D were measured and total body bone mineral density (BMD) was evaluated with dual energy X-ray absorptiometry (DXA).

Results: Patients had significantly higher levels of OPG (6.15±1.56 vs 5.01±1.5 pmol/l, P<0.001) and s-RANKL (logS-RANKL 5.97±0.63 vs 5.51±0.84, P=0.004). Patients also had lower levels of PTH (logPTH 3.25±0.52 vs 3.43±0.33, P=0.036) and magnesium (1.88±0.12 vs 2.03±0.12 mg/dl, P<0.001) and higher levels of ALP (√ALP 14.07±4.13 vs 12.6±3.24, P=0.05). Patients and controls had comparable 25(OH)vitD levels, while one third of both groups had low 25(OH)vitD levels (<20 ng/ml). Osteocalcin was highly correlated with CTX in both groups (r=0.75, P<0.001), indicating coupling of bone resorption and formation. OPG and s-RANKL were associated in controls (R²=0.15, P=0.021) but not in patients (R²=0.006, P=0.64), possibly indicating an osteoclastic disorder. Bone formation was not significantly affected. BMD had greater variance in patients. Furthermore, longer T1DM duration was associated with lower BMD Z-scores (r=−0.41, P=0.009).

Conclusion: RANKL/OPG axis seems to be significantly activated in patients with T1DM. These changes could indicate abnormal osteoclast function and could be associated with the lower bone mass, found in patients with longer disease duration.