The study of new biomarkers of bone metabolism of sclerostin and cathepsin K in patients with type 2 diabetes mellitus

BACKGROUND: Deterioration of bone tissue in type 2 diabetes mellitus (T2D): lead to the increased bone brittleness and to higher risk of low-energy fractures. AIM: to study serum levels of sclerostin and cathepsin K in assessing bone metabolism in patients with type 2 diabetes mellitus. MATERIAL AND METHODS: 102 postmenopausal women aged from 46 to 67 years were examined. All patients were divided into 4 groups: the first group included 39 patients with type 2 diabetes (T2DM) and postmenopausal osteoporosis (PO), the second group — 25 patients with PO without T2DM, the third group included 21 patients with T2DM but without PO, and the fourth group (control) — 17 people. Patinets of all groups were tested for ionized calcium, phosphorus, total alkaline phosphatase (ALP), parathyroid hormone, 25 (OH) vitamin D, bone mineral density in groups I, II, and IV, levels of sclerostin and cathepsin Kin seru, were also obtained. RESULTS: No statistically significant differences have been observed between groups in sclerostin levels, a positive correlation was found between sclerostin and НbА1с (r=0.43; p=0.009) in the group of patients with T2DM and PO, a negative correlation was found between sclerostin and ionized calcium (r=–0.45; p=0.037) in the group of patients with PO. Cathepsin C in the first group was lower than in the second group (p=0.046), but taking into account Bonferroni correction this difference was not statistically significant. In the first and third groups, 25 (OH) vitamin D was lower than in the groups without T2D. The ALP negatively correlated with the duration of the postmenopause (r=–0.39 and r=–0.64; р=0.05, respectively). CONCLUSIONS: Cathepsin С was lower in patients with T2DM2 and PO, which may indirectly indicate a decreased bone resorption. Concentration of sclerostin, which plays a key role in the mechanism of inhibiting osteoblastogenesis, positively correlated with НbА1с.