Low serum osteocalcin levels are associated with diabetes mellitus in glucocorticoid treated patients.

ABSTRACT

Bone turnover markers are decreased in GC-treated subjects with DM. Decreased OC levels in GC-treated patients were associated with an increased risk of DM. These results suggest the involvement of OC in glucose homeostasis regulation in DM. INTRODUCTION: Osteocalcin (OC) is involved in the regulation of glucose homeostasis. Glucocorticoid (GC) treatment is associated with impaired osteoblast function, decreased OC levels, and the development and/or worsening of pre-existing diabetes mellitus (DM). Whether decreased OC levels in GC-treated subjects contribute to DM is not well known. The aim of this study was to analyse whether OC levels in GC-treated patients are associated with the presence of DM. METHODS: One hundred twenty-seven patients (aged 61.5 ± 17.9 years) on GC treatment were included. GC dose, treatment duration, presence of DM and bone formation (OC, bone ALP, PINP) and resorption markers (urinary NTX, serum CTX) were analysed. The cut-offs of each bone turnover marker (BTM) for the presence of DM were evaluated and optimised with the Youden index and included in the logistic regression analysis. RESULTS: Among the patients, 17.3% presented DM. No differences were observed in GC dose or duration or the presence of fractures. Diabetics showed lower levels of OC (7.57 ± 1.01 vs. 11.56 ± 1; p < 0.001), PINP (21.48 ± 1.01 vs. 28.39 ± 1; p = 0.0048), NTX (24.91 ± 1.01 vs. 31.7 ± 1; p = 0.036) and CTX (0.2 ± 1.01 vs. 0.3 ± 1; p = 0.0016). The discriminating BTM cut-offs for DM presence were < 9.25 ng/mL for OC, < 24 ng/mL for PINP, < 27.5 nMol/mM for NTX and < 0.25 ng/mL for CTX. In a multivariate logistic regression model adjusted for GC dose, BMI, age and the above four BTMs, only OC remained independently associated with DM presence. Thus, in a model adjusted for GC dose, BMI and age, OC was significantly associated with DM (OR 6.1; 95%CI 1.87-19.89; p = 0.001). CONCLUSION: Decreased OC levels in GC-treated patients are associated with increased odds of DM, and only OC was independently associated with DM in a model including four BTMs.