Serum concentrations of osteocalcin, procollagen type 1 N‐terminal propeptide and beta‐CrossLaps in obese subjects with varying degrees of glucose tolerance

Summary Aims  To evaluate serum levels of osteocalcin (OC), procollagen type 1 N-terminal propeptide (P1PN) and beta-CrossLaps (beta-CTx) in obese subjects and their relationship with glucose metabolism parameters. Subjects  Sixty-four obese patients classified according to their glucose tolerance. Design  Case–control study. Measurements  A 75-g oral glucose tolerance test was performed with determinations of glucose and insulin between 0 and 120 min. Serum concentrations of OC, P1PN and beta-CTx were quantified in baseline samples. Results  Patients with type 2 diabetes (T2D, n = 24) exhibited OC serum levels (2·6 ± 1·0 nm) significantly lower than those found in subjects with normal glucose tolerance (NGT, n = 20, 3·9 ± 1·5 nm, P < 0·01). We found no significant differences in P1NP and beta-CTX levels among patients with NGT, prediabetes and T2D. Multiple regression analysis showed that serum OC concentration, but not P1NP or beta-CTx levels, was independently related to 2-h plasma glucose. Conclusion  Obese patients with T2D showed significantly reduced levels of OC in comparison with patients with lower degrees of glucose tolerance derangement. Our results also suggest that OC was the only bone marker independently related to the degree of glucose metabolism derangement in these patients.