Endocrine Abstracts

Introduction: The relationship between diabetes mellitus (DM) and osteoporosis is controversial. Both Type 1 DM and Type 2 DM have been associated with higher risk of fractures, whereas BMD is increased in Type 2 and decreased in Type 1 DM. In primary hyperparathyroidism (PHPT) a higher prevalence of Type 2 DM has been found but the influence of DM on BMD is unknown.

Subjects and methods: In a consecutive series of 262 patients with PHPT (age, mean±SD, 59.1±13.6 years; BMI: 25.5±5.2 kg/m²; PTH: 200.9±164.8 pg/ml; Ca:11.1±1.1 mg/dl) we measured BMD by DXA at forearm, lumbar spine and femur as well as biochemical parameters of the illness and HbA1C levels. We compared data of patients with DM (DM+, n=29, F/M 23/6; age: 64.7±11.5 years; BMI: 28.7±6.3 kg/m²) with those without DM (DM−, n=233; F/M 172/61; age: 58.4±13 years; BMI: 25.1±4.9 kg/m²).

Results: DM+ were older (P<0.01) and had higher BMI (P<0.0008) than DM−, while gender ratio, PTH, Ca, creatinine, 25OHD3 and calciuria were not different. In DM+, BMD at femur was higher than in DM− (P<0.02) even after adjustment for age and BMI, while BMD at forearm and lumbar spine were similar. In DM+, HbA1C was negatively associated with BMD at lumbar spine (r=−0.615; P<0.03) and this association was confirmed in a multivariate analysis including age and PTH (beta −0.632; P<0.03).

Conclusions: Our data indicate that in PHPT, as reported in the general population of Type 2 DM, the presence of diabetes is associated with increased BMD at femur and thus with a reduced fracture risk; on the other hand, a poor glycemic control seems to influence negatively BMD at lumbar spine, indicating a peculiar sensitivity of trabecular bone to this metabolic impairment.