THE INDEPENDENT EFFECTS OF TYPE 2 DIABETES MELLITUS AND CHRONIC KIDNEY DISEASE ON BONE TURNOVER MARKERS

Background. Chronic kidney disease (CKD) and type 2 diabetes mellitus (T2DM) are associated with disturbed mineral homeostasis and serum bone biomarkers. The interplay between T2DM and CKD on serum bone turnover markers (BTM) is unclear. Our aim was to describe the BTM in patients with T2DM, CKD or both. Methods. In this observational, single-centre, prospective study, we included 320 patients over 40 years, divided into four groups: T2DM and normal kidney function (n=142), T2DM and CKD (n=36), CKD and normal glucose metabolism (n=29) and healthy controls (n=113). We excluded patients treated for osteoporosis and with secondary osteoporosis. Patients were compared by age, levels of glycated hemoglobin, PTH, alkaline phosphatase, osteocalcin (OC), CTx and 25 OH vitamin D. Results. Univariate analysis showed that GFR correlated significantly with PTH (r=0.37), OC (r=0.43) and CTX (r=0.45) in the diabetes group but only with PTH (r=0.34) in the non-T2DM group. Multivariate analysis showed that GFR remained significantly correlated with the same bone markers even after adjustment for age, sex or 25(OH)D levels. Diabetics seem to have lower levels of alkaline phosphatase (68 +/- 22.1 U/L) and CTX (0.37 +/- 0.24 ng/mL) than those without diabetes (76.7 +/- 29.6. U/L and 0.5 +/- 0.19 ng/mL, respectively). There was no correlation between BTM and glycated hemoglobin. Conclusions. Bone turnover markers correlate with GFR, particularly in patients with T2DM. However, alkaline phosphatase is lower in T2DM than in non-T2DM.